Report on the Radiolaria/Cyrtoidea

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Report on the Radiolaria
by Ernst Haeckel

Cyrtoidea

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1584086Report on the Radiolaria — CyrtoideaErnst Haeckel

Suborder III. CYRTOIDEA, Haeckel, 1862.

Cyrtida, Haeckel, 1862, Monogr. d. Radiol., pp. 272, 280.
Cyrtoidea vel Cyrtida, Haeckel, 1881, Prodromus, pp. 425-439.
Polycystina solitaria, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, pp. 53, 54.
Monodictya nassellaria, Ehrenberg, 1875, Abhandl. d. k. preuss. Akad. d. Wiss. Berlin, pp. 156, 157.

Definition.—Nassellaria with a complete lattice-shell, exhibiting a simple or reduced cephalis, which is neither bilocular nor lobate, without sagittal constriction.

The order Cyrtoidea, described by me in 1862 as the family Cyrtida, is by far the largest of all the main groups of Radiolaria, and remarkable from the extraordinary variety of forms and the number of species. In the following system more than eleven hundred species are described, comprising about one-fourth of the number of species in the whole class of Radiolaria. This astonishing variety, however, is not effected by development of a large number of different types, but by an extraordinary variability within certain restricted boundaries, similar to what is seen among insects and birds. The number of genera, therefore, is comparatively small, and they may all be disposed into four families only, which in my Monograph (1862, p. 280) were distinguished as Monocyrtida, Dicyrtida, Tricyrtida and Stichocyrtida. If we divide these four groups in the following pages into twelve families and twenty-four subfamilies, we are guided by practical considerations only, hoping thereby to give a better survey of the difficult labyrinth of Cyrtoidean morphology.

The Cyrtoidea are characterised by this wonderful richness of specific forms not only in the present seas, but also for millions of years in the former ages of our globe. The majority of all the fossil Radiolaria which are now known belong to this group, and many species of it are so common that great rocks are formed by their union. The fact was first observed by Ehrenberg, who in his first system of Polycystina (1847, loc. cit., p. 54) enumerated forty-four genera and two hundred and eighty-two species; the Cyrtoidea, his Polycystina solitaria, form the preponderant majority of the whole class, viz., twenty-five genera and one hundred and ninety-three species.

In this first system (of 1847), as well as in the last systematic table of Ehrenberg (of 1875, loc. cit.), the Cyrtida as "Polycystina solitaria" are opposed to all other Radiolaria, as "Polycystina composita." The former bear the definition "Testæ siliceæ spatio interno ample pervio, aut passim levius transverse constricto"; the latter, however, "Testæ siliceæ spatio interno celluloso aut strictura longitudinali constricto." In reality these definitions are insufficient, and the conclusions which Ehrenberg derived from the organisation of the Polycystina solitaria and composita, were quite erroneous. So also are the definitions of the three families into which he divided the Polycystina solitaria, afterwards (in 1875) called by him "Monodictya nassellaria." These three families were the Halicalyptrina, Lithochytrina and Eucyrtidina. With these were also united the three genera of Botryodea known to Ehrenberg (Lithobotrys, Botryocampe, Botryocyrtis). We entirely separate these here from the true Cyrtida, on account of their lobate or multilocular cephalis.

Whilst Ehrenberg only knew the skeleton of the Polycystina solitaria, the first observations of living Cyrtida were published by Johannes Müller, 1858, in his fundamental treatise. He gave the first description and figures of the central capsule of this group, with the characteristic lobes developed from its basal part; and of the pseudopodia radiating on all sides (loc. cit., Taf. vi.). The forms described by him were all Mediterranean, one Dicyrtid (Lithomelissa mediterranea), two Tricyrtids (Eucyrtidium zancleum and Pterocanium charybdeum), and one Stichocyrtid (Lithocampe tropeziana).

In my monograph (1862, p. 272-341) I gave a detailed description of all known and some new Cyrtida, and characterised this family by the fundamental monaxonial form of the shell, with two different poles (an upper apical and a lower basal pole), and by the unipolar growth, beginning from the apical pole. I pointed out also the peculiar structure of the monaxonial central capsule. At that time I divided the Cyrtida into five subfamilies, in which, however, the Spyroidea (= Zygocyrtida), and the Botryodea (= Polycyrtida) were united with the true Cyrtoidea (Monocyrtida, Dicyrtida, Stichocyrtida).

The astonishing number of new and interesting forms of Cyrtida which I found in the rich collection of the Challenger (beginning from 1876), and mainly in the Radiolarian ooze of the Central Pacific (Stations 263 to 274), enabled me to give in my Prodromus, in 1881, a greatly enlarged and amended system of this important group. I separated there the Spyroidea (= Zygocyrtida), and the Botryodea (= Polycyrtida) from the true Cyrtoidea by restricted definition, pointing out the essential differences in the structure of the cephalis in these groups of Cyrtellaria. The latter name, as here used, is therefore identical with the "Cyrtida" of my Monograph. In the Prodromus I divided the true Cyrtida (p. 426) into five subfamilies and thirty tribes, corresponding to the differences in the number of the shell-joints and of the radial apophyses, and in the shape of the closed or open mouth. These groups are here retained, but reduced to four families and twenty-four subfamilies, since the Tetracyrtida are better united with the Stichocyrtida (compare below).

Richard Hertwig in his work Organismus der Radiolarien (1879, pp. 74 to 86) gave the first accurate description of the finer structure of the central capsule of the Cyrtida, and pointed out their character as true Monopylea, with porochora and podoconus, and the peculiar shape of its nucleus. He also published excellent figures of some interesting new species.

O. Bütschli, 1882, in his valuable paper entitled: "Beiträge zur Kentniss der Radiolarien-Skelette, insbesondere der der Cyrtida" (Zeitschr. für wiss. Zool., vol. xxxvi. p. 485) made an attempt at a natural classification of the Cyrtida, which he derived from the Spyroidea or Zygocyrtida. As already mentioned above, we cannot accept this essay as the foundation of a true natural system, since the affinities of the Cyrtellaria (and of the Nassellaria as a whole) are far more complicated and difficult than Bütschli supposed. His views were supported by accurate observations only on the structure of the fossil Cyrtoidea of Barbados; these, however, represent the minority only of the genera, and many interesting and important forms (mainly of true "Monocyrtida") remained unknown to Bütschli. A great part, however, of his observations are very useful, and his remarks on comparative morphology are very suggestive.

The Cyrtoidea may be divided into families and subfamilies according to three different principles, viz., (1) the number of joints into which the shell is divided by transverse strictures; (2) the number of radial apophyses which arise from the shell; (3) the shape of the basal mouth, which is either open or closed by a lattice-plate. At present every attempt of classification in this large group must be more or less artificial, since the affinities of the numerous smaller and larger groups are extremely complicated, and the ontogeny, the only sure guide in this phylogenetical labyrinth, is perfectly unknown. It seems therefore the most convenient to employ for our artificial classification, first, the number of shell-joints, second, the radial structure, and third, the shape of the mouth.

A. The number of joints into which the shell is divided by transverse constrictions, serves here for the distinction of four primary groups or suborders of the Cyrtoidea, viz., (1) Monocyrtida with one joint; (2) Dicyrtida with two joints; (3) Tricyrtida with three joints; and (4) Stichocyrtida with four or more joints. In my Prodromus (1881, p. 426) I divided the latter group into Tetracyrtida (with four joints), and Stichocyrtida (with five or more joints); but these two groups may be united, since the fourth and all the succeeding joints are of rather indifferent shape and of little morphological value. The three first joints, however, are usually very different and possess a high morphological importance, so that we distinguish the first joint as cephalis, the second as thorax, and the third as abdomen. The uppermost transverse constriction, which separates the two first joints, cephalis and thorax, is the collar stricture and is usually caused by an internal fenestrated septum, the cortinar septum. The second constriction, which separates the second and third joints (thorax and abdomen) is called the lumbar constriction. The following constrictions (in the Stichocyrtida) are indifferent and of little morphological interest, and require therefore no peculiar designation.

B. The radial structure, indicated by radial apophyses arising from the shell, offers three principal differences, according to which the whole group of Cyrtoidea may be divided into three large groups or sections, viz., (1) Pilocyrtida, or Cyrtoidea triradiata, with three radial apophyses; (2) Astrocyrtida, or Cyrtoidea multiradiata, with numerous radial apophyses (four to nine or more); and (3) Corocyrtida, or Cyrtoidea eradiata, without external radial apophyses. The majority of Cyrtoidea are Pilocyrtida, with three radial apophyses, which are probably homologous to the three primary feet of the Plectoidea and of Cortina (therefore "cortinar feet"). The Astrocyrtida, or the Cyrtoidea with a variable number of radial apophyses (at least four to six) may be derived from the Pilocyrtida by interpolation of secondary or interradial apophyses between the three primary or perradial apophyses. The Corocyrtida, however, or the Cyrtoidea without external radial apophyses, may have originated by reduction and loss of the latter, either from the Pilocyrtida or from the Astrocyrtida.

C. The shape of the basal mouth in the Cyrtoidea exhibits two essential differences only, viz., (1) the terminal mouth of the shell is a simple wide opening in the Stomocyrtida, or (2) the terminal mouth is closed by a lattice-plate, in the Clistocyrtida. As these two different cases occur in all the twelve families, which we have distinguished according to the differences in the number of joints and in the radial structure, we get altogether twenty-four subfamilies which are synoptically arranged in the following table:—

Synopsis of the four sections, twelve families and twenty-four subfamilies of CYRTOIDEA.	PILOCYRTIDA. Cyrtoidea triradiata. (Three radial apophyses.)		ASTROCYRTIDA. Cyrtoidea multiradiata. (Four to nine or more apophyses.)		COROCYRTIDA. Cyrtoidea eradiata. (No radial apophyses.)
Mouth of the shell.	Aperta.	Clausa.	Aperta.	Clausa.	Aperta.	Clausa.
MONOCYRTIDA. (Cyrtoidea monothalamia).	Tripocalpida.		Phænocalpida.		Cyrtocalpida.
MONOCYRTIDA. (Cyrtoidea monothalamia).	Archipilida.	Archiperida.	Archiphormida.	Archiphænida.	Archicorida.	Archicapsida.
DICYRTIDA. (Cyrtoidea dithalamia).	Tripocyrtida.		Anthocyrtida.		Sethocyrtida.
DICYRTIDA. (Cyrtoidea dithalamia).	Sethopilida.	Sethoperida.	Sethophormida.	Sethophænida.	Sethocorida.	Sethocapsida.
TRICYRTIDA. (Cyrtoidea trithalamia).	Podocyrtida.		Phormocyrtida.		Theocyrtida.
TRICYRTIDA. (Cyrtoidea trithalamia).	Theopilida.	Theoperida.	Theophormida.	Theophænida.	Theocorida.	Theocapsida.
STICHOCYRTIDA. (Cyrtoidea polythalamia).	Podocampida.		Phormocampida.		Lithocampida.
STICHOCYRTIDA. (Cyrtoidea polythalamia).	Stichopilida.	Stichoperida.	Stichophormida.	Stichophænida.	Stichocorida.	Stichocapsida.

The cephalis, or the first shell-joint of the Cyrtoidea, is in the majority homologous with the cephalis of the Spyroidea, from which it differs in the reduction of the sagittal ring and the absence of the corresponding sagittal constriction; its cavity is therefore simple, not bilocular. Its homology with the original cephalis of the Spyroidea cannot be doubted, when its base exhibits the typical basal pores of the Semantida. But in many cases these are wanting, and in a great number of Cyrtoidea (mainly of Monocyrtida) there is more or less evidence that the original cephalis is lost, and that the real first joint is the thorax, the original second joint. At present it is quite impossible to distinguish between the former and the latter shells, and therefore in the following descriptions the first joint is always named cephalis and the second thorax. In future, when the affinities of the Cyrtoidea become better known, it will be necessary to distinguish the "Archicephalis," or true cephalis of all Spyroidea and of the majority of Cyrtoidea, from the "Pseudocephalis" or the false cephalis of the minority (e.g., of many Monocyrtida aperta, Archipilida, Archiphormida, Archicorida, &c.).

The thorax, or the second shell-joint of the Cyrtoidea, is in the majority homologous with the thorax of the Phormospyrida and Androspyrida, and therefore developed by apophyses, which arise from the base of the cephalis and become united by transverse branches forming a lattice-plate. Its size is generally in inverse proportion to that of the cephalis. The more the cephalis becomes reduced, the more the thorax is developed. Its form is very variable, usually three-sided pyramidal or prismatic in the triradiate, polyhedral in the multiradiate, and conical or cylindrical in the eradiate Cyrtoidea. Its terminal mouth is either a simple wide opening, or closed by a lattice-plate. In the majority of Cyrtoidea the thorax is separated from the cephalis not only by the external collar constriction, but also by the internal cortinar septum, a horizontal lattice-plate which exhibits the typical basal pores of the Semantida (usually two smaller jugular and two larger cardinal pores). But this septum is often reduced or perfectly lost, and then the external collar constriction alone indicates the separation of the cephalis and the thorax.

The abdomen, or the third shell-joint of the Cyrtoidea, absent in the Monocyrtida and Dicyrtida (as also in all Spyroidea), occurs constantly in all Tricyrtida and Stichocyrtida. It is a simple large chamber in the Tricyrtida, but forms an annulated body, composed of a variable number of successive joints, in the Stichocyrtida. The constrictions between these joints, and also the lumbar constriction, between abdomen and thorax, are usually provided with a lattice-girdle, projecting into the cavity of the shell, like a diaphragm. Usually this horizontal girdle bears only a single circle of pores, rarely two or more. In many Cyrtoidea it is replaced by a solid horizontal ring of silex, and often it is wanting. It originates by the insertion of the following shell-joint, which takes place not on the terminal mouth of the preceding joint, but somewhat above it. The annular joints of the Stichocyrtida succeeding the third joint, and very variable in number, may be regarded either as a series of new postabdominal chambers, succeeding the true abdomen, or as secondary joints of the annulated abdomen itself. The latter view may be sustained by the fact that these joints are usually of an indifferent shape, and do not possess the characteristic features which we find in the first three joints, the abdomen, the thorax and the cephalis.

The lattice-work of the shell exhibits in the Cyrtoidea an extraordinary variety, similar to that of the Sphæroidea; it serves in the first place for the distinction of species. The three first joints of the shell are often distinguished by the different character of the lattice-work. The cephalis has usually very small and simple pores. The lattice-work of the thorax is often characterised by radial structures. The pores of the abdomen are usually very numerous and regular. The numerous joints in the annulated abdomen of the Stichocyrtida commonly exhibit little variety.

The closure of the mouth, effected by a convex or horizontal terminal lattice-plate, has a different signification in the Monocyrtida and in the jointed Cyrtoidea. In the Monocyrtida clausa this closing plate is the original cortinar plate or the basal plate of the cephalis. In the jointed Cyrtoidea, however, the lattice-plate which closes the terminal mouth of the thorax or of the abdomen (of the last annular joint in the Stichocyrtida), is produced by central union of the convergent edges, which grow centripetally from the margin of the mouth of the last joint towards its centre.

The radial apophyses arising from the shell of the Cyrtoidea may probably be always derived from that tripodal structure which is found in all Plectoidea, in Cortina and Cortiniscus among the Stephoidea, and in the majority of Spyroidea. Therefore the prototype of this radial structure would be Plagoniscus and Cortina, with four radial spines united in a common point, the cortinar centrum; an ascending apical horn and three descending basal feet. The odd posterior or caudal foot is usually similar in shape to the two paired anterior or pectoral feet, but may be distinguished from these latter by its relation to the apical horn. Very frequently an internal vertical free columella arises in the cephalis, or instead of it an ascending rib in the dorsal wall of the cephalis, which connects the base of the apical horn with the origin of the caudal foot. This is probably the remaining part of the sagittal ring. More rarely also a part of the ventral rod of the latter is preserved, or on the anterior pole of the basal rod of the cephalis an ascending procolumella arises which is inserted on the frontal face of the cephalis, and sometimes prolonged into a nasal horn (the rod, C, of Bütschli). These two odd horns, the posterior apical horn and the anterior nasal horn, are usually different and divergent. In some genera a variable number of accessory radial horns is developed on the convex face of the cephalis. In many hornless genera the free apical horn is lost, but not unfrequently the columella is preserved which connects the caudal foot with that point of the cephalis, in which formerly the apical horn was inserted.

The three primary radial beams, corresponding to the three basal feet of Plectaniscus and Cortina, exhibit in the Cyrtoidea the greatest variety in form and size, and chiefly in their relation to the shell, the latter serving mainly for the distinction of genera. Originally these three cortinar beams arise from the basal plate of the cephalis, the odd caudal foot appearing as a prolongation of the basal rod of that plate, and the paired pectoral feet as prolongations of its coracal rods (between the jugular and cardinal pores). The lattice-work of the thorax is developed usually between the three cortinar feet, more rarely inside or outside of them. Therefore the three beams appear commonly as three divergent ribs in the wall of the thorax, and continue over its basal mouth as three free terminal feet. With the increasing length of the shell and the number of its joints the three radial ribs are also prolonged, and their free distal ends may be prominent at very different points, either as three lateral wings or as three terminal feet. These are either solid spines or lattice-plates, sometimes more or less ramified.

The three radial apophyses are prevalent in the majority of the Cyrtoidea, which we call "Pilocyrtida" (or Cyrtoidea triradiata). Their number increases in the Astrocyrtida (or Cyrtoidea multiradiata). The most frequent cases of multiplication are here caused by the development of six or nine radial apophyses; these may be enclosed ribs, or lateral wings, or terminal feet. In the sexradial Cyrtoidea there are three secondary or interradial apophyses interpolated between the three primary or perradial; in the nine-radial Cyrtoidea, however, there are six adradial apophyses interpolated.

A third and last great group is formed by the Corocyrtida or Cyrtoidea eradiata. These exhibit no radial apophyses, neither enclosed ribs, nor free lateral wings, nor terminal feet. But in a great number of them internal traces of an original triradiate structure are visible, mainly in the cortinar septum between cephalis and thorax; this often exhibits three or four, and sometimes six cortinar or collar pores, of the same typical shape as in the triradial Spyroidea. Sometimes even an internal columella with three radial branches is preserved, as in Axocorys. It is therefore very probable that a great part of these Cyrtoidea eradiata (if not all) may be derived from triradiate or multiradiate ancestral forms, by reduction and loss of the radial apophyses. In another part of this group, mainly in the Monocyrtida eradiata (Cyrtocalpida) it is possible, or even probable, that their eradiate shell has originated independently from Nassellida, and that they have no true relation to radial Cyrtoidea.

The Central Capsule of the Cyrtoidea, first observed by J. Müller (1858), and more fully described in my Monograph (1862), was very accurately examined by Richard Hertwig (1879). His observations were confirmed by numerous new forms, which I was able to examine in well-preserved preparations of the Challenger. The central capsule, according to these, exhibits the same typical shape, which is characteristic of all Monopylea (with porochora and podoconus), and may be derived with the latter from the common ancestral forms, Cystidium and Nassella (= the skeletonless Nassellida). In the majority, however, of Cyrtoidea, the capsule develops on its basal face a number of depending lobes, as were also found in some Spyroidea (and probably also Botryodea). In this respect we may distinguish two main forms of the capsule in the Cyrtellaria, viz., the primary simple, not lobate form, and the secondary lobate form. The central capsule is originally always enclosed in the cephalis, and has there a simple, subspherical, ellipsoidal or ovate form. As soon as their growth increases, and the enclosing cephalis becomes too narrow, it sends out prolongations in the form of basal lobes, which depend from its base, and proceed through the pores of the basal lattice of the cephalis, or the cortinar pores. In the great majority of Cyrtoidea in which the capsule was observed, either three or four such lobes were seen (already described by J. Müller). Of course this number depends upon the number of cortinar pores, which is either three or four; therefore in the Cyrtoidea with three pores in the cortinar plate, we find three lobes of the central capsule (an odd posterior and two paired anterior); in the Cyrtoidea, however, with four pores in the cortinar plate (the majority) we find four lobes of the central capsule (two smaller anterior jugular and two larger posterior cardinal lobes). Usually each lobe is ovate or pear-shaped and encloses a large oil-globule, and often also an apophysis of the cell-nucleus.

Section I. MONOCYRTIDA, Haeckel, 1862, Monogr. d. Radiol., pp. 280, 281.

Definition.—Cyrtoidea monothalamia, with simple, not jointed shell (or cephalis), without transverse constrictions.

Synopsis of the three Families and six Subfamilies of Monocyrtida.

Family LIX. Tripocalpida. Three radial apophyses.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	Mouth open,	1. Archipilida.
		Mouth closed,	2. Archiperida.
Family LX. Phænocalpida. Numerous radial apophyses.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	Mouth open,	3. Archiphormida.
		Mouth closed,	4. Archiphænida.
Family LXI. Cyrtocalpida. No radial apophyses.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	Mouth open,	5. Archicorida.
		Mouth closed,	6. Archicapsida.

Family LIX. Tripocalpida, n. fam.

Archipilida et Archiperida, Haeckel, 1881, Prodromus, pp. 427, 429.

Definition.—Monocyrtida triradiata. (Cyrtoidea with a simple, not jointed shell, representing a simple cephalis, with three radial apophyses.)

The family Tripocalpida, composed of the Archipilida and Archiperida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is quite simple, without transverse constriction, and bears three radial apophyses. The two subfamilies differ in the shape of the basal mouth, which in the Archipilida is a simple wide opening, in the Archiperida closed by a lattice-plate; the former are here divided into eight, the latter into seven different genera.

Only three species of this family were hitherto described, all three belonging to the Archipilida, viz., (1) Tripocalpis galea (fossil in Barbados, figured by Ehrenberg, 1875, as Halicalyptra galea), (2) Tripodiscium campanula (fossil in Sicily, figured by Stöhr, 1880, as Carpocanium); and (3) Tridictyopus elegans, of which Richard Hertwig gave an excellent description in 1879, with an accurate figure of the central capsule. All the other species of the family (seventy) are new.

The shell in the majority of Tripocalpida is ovate or campanulate, sometimes conical or three-sided pyramidal. Three radial apophyses are constantly distinct, either three lateral wings or three terminal feet; these are usually solid spines, rarely lattice-plates. The top of the shell usually bears an apical horn, rarely two or more horns; often the horn is wanting. The lattice-work of the shell is very various in the different species, and often of a remarkable structure (Pl. 51, figs. 6-8; Pl. 98, figs. 4-8). The cavity of the shell is in all Archipilida, and in a part of the Archiperida (Peridium, Archipera, Archibursa) quite simple. In the other part of the Archiperida, however, constituting the peculiar group of Euscenida (genera 504-507), a vertical columella arises in the centre of the basal plate, and is prolonged upwards in the apical horn; this columella is either simple (Euscenium, Archiscenium) or branched (Cladoscenium, Pteroscenium); in the latter case the ascending branches are disposed in triradiate verticils and are inserted on the inner face of the shell (compare Pl. 53, figs. 11-16, and Pl. 98, figs. 1-4).

The phylogenetic origin of the Tripocalpida may be very divergent, and their morphological affinity to the other Nassellaria is a very complicated problem. The Euscenida (genera 504-507) may be derived directly from the Plagonida (Plagoniscus) or Plectanida (Plectaniscus). The Archibursida (genera 508-510) however, manifest a closer affinity to the Tripospyrida, and may be derived from them by reduction of the sagittal ring and constriction. In these two groups of Archiperida the shell may be regarded as a true cephalis. In the Archipilida, however, where the shell has a wide basal opening and the three radial ribs arise originally from the base of the apical horn, the shell itself may correspond to the thorax of the Dicyrtida, and may be derived from these by loss of the cephalis. This is the more probable, as sometimes a small remnant of the reduced cephalis is preserved (Pl. 98, fig. 8). None of these difficult questions can be answered until a much closer morphological knowledge of the Tripocalpida is acquired.

Synopsis of the Genera of Tripocalpida.

I. Subfamily Archipilida. Basal mouth of the shell a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell with three lateral ribs or wings, with or without terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Three terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Apex with a horn,	496. Tripocalpis.
						No apical horn,	497. Tripodonium.
				Six to nine or more terminal feet.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	No apical horn,	498. Tripterocalpis.
				No terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Apex with a horn,	499. Trissopilium.
						No apical horn,	500. Archipilium.
		Shell without lateral ribs or wings but with three terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Feet simple or branched, not latticed.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	Apex with a horn,	501. Tripilidium.
						No apical horn,	502. Tripodiscium.
				Feet latticed.		Apex with a horn,	503. Tridictyopus.
II. Subfamily Archiperida. Basal mouth of the shell closed by a lattice-plate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell in its axis with a free (simple or branched) internal columella, prolonged into an apical horn.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell with three free feet, without lateral lattice-wings.	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Columella simple,	504. Euscenium.
						Columella branched,	505. Cladoscenium.
				Shell with three lateral lattice-wings, connecting the three feet with the horn.	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Columella simple,	506. Archiscenium.
						Columella branched,	507. Pteroscenium.
		Shell with simple cavity, without free columella. Three free basal feet.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	One apical horn,	508. Peridium.
						Two or more horns,	509. Archipera.
						No apical horn,	510. Archibursa.

Subfamily 1. Archipilida, Haeckel, 1881, Prodromus, p. 427.

Definition.—Tripocalpida with the basal mouth of the shell open (vel Monocyrtida triradiata aperta).

Genus 496. Tripocalpis,^[1] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs prolonged into three terminal feet. Apex with a horn.

The genus Tripocalpis opens the series of Archipilida, or of those Monocyrtida in which the monothalamous shell exhibits a distinct triradial structure, and a simple open mouth, without cortinar lattice. Tripocalpis is probably the most primordial of the Archipilida, and has three lateral ribs, which are prolonged into three free terminal feet, and connected in the apex of the pyramidal or campanulate shell with the apical horn. It may probably be derived from Dictyophimus by loss of the cephalis. The central capsule is simple, spherical, or ellipsoidal.

1. Tripocalpis plectaniscus, n. sp.

Shell three-sided pyramidal, smooth, about as long as broad, with irregular polygonal pores and thin bars. Apical horn stout, three-sided pyramidal, about as long as the shell. From the three edges of its base arise three prominent straight radial ribs, which are prolonged into three large divergent feet, of equal size and the same form as the horn.

Dimensions.—Shell 0.1 diameter, horn and feet 0.12.

Habitat.—Tropical Pacific (Philippine Sea), Station 206, depth 2100 fathoms.

2. Tripocalpis galea, Haeckel.

Halicalyptra galea, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 74, Taf. ii. fig. 10.

Shell campanulate, rough, about as long as broad, with irregular roundish pores and thick bars. Apical horn stout, three-sided pyramidal, scarcely one-fourth as long as the shell. Beyond its base there arise three prominent, slightly curved lateral ribs, which are prolonged into three pyramidal, slightly divergent stout feet, somewhat shorter than the shell.

Dimensions.—Shell 0.08 to 0.09 diameter, horn 0.02, feet 0.07.

Habitat.—Fossil in Barbados.

3. Tripocalpis tricostata, n. sp.

Shell ovate campanulate, one and a half times as long as broad, with regular circular pores, disposed in alternate longitudinal rows. Apical horn three-sided pyramidal, stout, half as long as the shell. In the middle of the shell there arise three wing-like lateral ribs, which are prolonged into three broad, slightly curved, divergent terminal feet.

Dimensions.—Shell 0.12 long, 0.08 broad, horn and feet 0.06 to 0.08.

Habitat.—Fossil in Barbados.

4. Tripocalpis triserrata, n. sp. (Pl. 51, fig. 6).

Shell ovate, nearly twice as long as broad. The three sides of the shell, between the three large ribs, are provided each with nine delicate parallel, longitudinal, slightly curved ribs, alternating with ten longitudinal rows of regular circular pores about as broad as the bars. Apical horn short and broad, three-sided pyramidal; from the three edges of its base there arise three wing-like serrate main ribs, which are prolonged into three short pyramidal terminal feet.

Dimensions.—Shell 0.12 long, 0.07 broad, horn and feet 0.01.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

5. Tripocalpis cortinaris, n. sp. (Pl. 97, fig. 3).

Shell hemispherical, one and a half times as broad as long, with regular, circular, hexagonally framed pores, Apical horn stout, three-sided pyramidal, with three serrate edges. From the base of the latter arise three strongly dentate and curved lateral ribs, with recurved teeth, and these are prolonged into the serrate convex edge of the three basal feet, which are crescentic and twice as long as the shell.

Dimensions.—Shell 0.07 long, 0.1 broad; horn 0.06 long, feet 0.14 long.

Habitat.—Indian Ocean, Cocos Islands (Rabbe), surface.

Genus 497. Tripodonium,^[2] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs prolonged into three terminal feet. Apex without horn.

The genus Tripodonium differs from the preceding Tripocalpis, its probable ancestral form, only in the loss of the apical horn (already very small in some forms of the latter). It bears therefore to the latter the same relation that Sethopilium does to Dictyophimus.

1. Tripodonium campanulatum, n. sp.

Shell campanulate, somewhat broader than high, with regular circular pores, twice as broad as the bars. Three broad lateral wings, lamellar, triangular, are prolonged over the peristome into three short triangular lamellar feet one-fourth as long as the shell.

Dimensions.—Shell 0.08 long, 0.09 broad; feet 0.02 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Tripodonium ovatum, n. sp.

Shell ovate, one and one-third times as long as broad, with numerous and small circular pores, scarcely as broad as the bars. Three prominent longitudinal ribs, arising in the lower half of the shell-wall, are prolonged into three divergent conical curved feet, about half as long as the shell.

Dimensions.—Shell 0.12 long, 0.09 broad; feet 0.06 long.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 498. Tripterocalpis,^[3] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral wings and a peristomial corona of numerous terminal feet. Shell ovate, with constricted mouth, without apical horn.

The genus Tripterocalpis is distinguished from the other Archipilida by the remarkable combination of three lateral wings and of numerous (six to nine or more) terminal feet. It may be derived directly from the preceding Tripocalpis by multiplication of the terminal feet. These are sometimes obliquely directed. The central capsule is ellipsoidal or ovate, and fills up the greater part of the shell.

1. Tripterocalpis phylloptera, n. sp. (Pl. 51, fig. 1).

Shell slender, ovate, nearly twice as long as broad. Pores circular, of different sizes and at unequal distances. Along the lower half of the shell there arise three broad triangular lamellar wings. Peristome with twelve conical, nearly parallel and vertical feet, about one-sixth as long as the shell.

Dimensions.—Shell 0.2 long, 0.12 broad; wings 0.1 long, feet 0.03 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Tripterocalpis conoptera, n. sp. (Pl. 51, fig. 2).

Shell ovate, nearly as broad as long. Pores regular, circular, quincuncial, twice as broad as the bars. In the middle of the shell there arise three conical, smooth, divergent wings, about half as long as the shell. Peristome with six short triangular, oblique, convergent feet.

Dimensions.—Shell 0.16 long, 0.14 broad; wings 0.09 long; feet 0.02 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Tripterocalpis ogmoptera, n. sp. (Pl. 51, figs. 3-5).

Shell ovate, nearly as broad as long. Pores small and numerous, circular or roundish, partly confluent, double-contoured (fig. 4). In the middle of the shell there arise three very large conical divergent wings, which are longitudinally striped and longer than half the shell. Peristome with nine short triangular, oblique, convergent feet.

Dimensions.—Shell 0.18 long, 0.16 broad; wings 0.12 long, feet 0.02 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 499. Trissopilium,^[4] Haeckel, 1881, Prodromus, p. 427.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs or wings. Mouth smooth, without terminal feet. Apex with a horn.

The genus Trissopilium and the following nearly allied Archipilium differ from the other Archipilida in the absence of terminal feet, the peristome being quite simple, and truncate. But there are three lateral wings, arising either from the apex or from the lateral sides of the monothalamous shell. Trissopilium may perhaps be derived from Lithomelissa by reduction of the cephalis.

1. Trissopilium tetraplecta, n. sp.

Shell in the upper half three-sided pyramidal, in the lower half inversely hemispherical, of equal length and breadth. Pores irregular, roundish, in the upper half larger. From the apex there diverge four equal, straight and stout, three-sided pyramidal spines, one of which is vertically ascending (the horn), the three others obliquely descending (the wings). The distal half of the latter is free, whilst the proximal half forms three ribs, enclosed in the shell-wall. Mouth constricted, half as broad as the shell.

Dimensions.—Shell 0.08 long and broad, horn and wings 0.1 long.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Trissopilium lithomelissa, n. sp.

Shell ovate, one and one-third times as long as broad. Pores circular, of different sizes, small and numerous. Apical horn very large, straight, cylindrical, vertical, longer than the shell. Three lateral wings shorter, arising from the middle of the shell, conical, curved, divergent. Mouth truncate, two-thirds as broad as the shell.

Dimensions.—Shell 0.11 long, 0.08 broad; horn 0.13 long, wings 0.09 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 500. Archipilium,^[5] Haeckel, 1881, Prodromus, p. 427.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs or wings. Mouth truncate, without terminal feet. Apex without horn.

The genus Archipilium differs from the nearly allied Trissopilium, its probable ancestral form, in the absence of the apical horn. The three lateral wings of the ovate shell are stout spines. It may also be derived from the similar Sethopilium by reduction and loss of the cephalis.

1. Archipilium orthopterum, n. sp. (Pl. 98, fig. 7).

Shell ovate, smooth, nearly cylindrical, scarcely broader than the truncate, widely open mouth. Pores numerous, irregular, roundish, of very different sizes. Three lateral wings arising from the middle zone, twice as long as the shell, straight, divergent, stout, cylindrical, longitudinally striped.

Dimensions.—Shell 0.08 long, 0.06 broad; wings 0.15 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Archipilium sigmopterum, n. sp.

Shell ovate, smooth, nearly campanulate, of equal length and breadth, one and one-third times as broad as the truncate, slightly constricted mouth. Pores scarce, irregularly formed and scattered, of very different sizes. Three lateral wings, stout, prismatic, about as long as the shell widely divergent and S-shaped, curved.

Dimensions.—Shell 0.08 diameter, wings 0.08 long.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

3. Archipilium cyrtopterum, n. sp.

Shell ovate, rough, twice as broad as the constricted mouth. Pores small and numerous, subregular, circular, smaller than the bars. Three lateral wings cylindrical, crescentic, in the upper half divergent, in the lower convergent, one and one-half times as long as the shell.

Dimensions.—Shell 0.09 long, 0.07 broad; wings 0.14 long.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 501. Tripilidium,^[6] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) without lateral ribs, with three simple or branched terminal feet and an apical horn.

The genus Tripilidium differs from Tripodonium in the absence of the three lateral ribs, and may be derived either from this ancestral form, or directly from Tripospyris (by loss of the sagittal ring and constriction); perhaps also from Lychnocanium (by reduction of the cephalis). We distinguish as two subgenera, Tristylocorys (with simple feet) and Tripodocorys (with branched feet).

Subgenus 1. Tristylocorys, Haeckel.

Definition.—Feet simple, not branched.

1. Tripilidium cortina, n. sp.

Shell campanulate, rough, about as long as broad. Pores subregular, circular, larger in the middle zone, twice to three times as broad as the bars. Mouth constricted, half as broad as the shell. Apical horn straight and stout, three-sided pyramidal, about as long as the shell. Three feet divergent, slightly S-shaped, curved, somewhat longer the the shell.

Dimensions.—Shell 0.1 diameter, horn 0.09 long, feet 0.13 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Tripilidium hemisphæricum, n. sp.

Shell hemispherical, smooth, nearly twice as broad as long. Pores large, with thin bars, irregular, roundish, of very different sizes. Mouth wide open. Apical horn conical, half as long as the shell. Three feet slender cylindrical, widely divergent, curved, nearly twice as long as the shell.

Dimensions.—Shell 0.08 long, 0.14 broad; horn 0.05 long, feet 0.15 long.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

3. Tripilidium lychnocanium, n. sp.

Shell hemispherical, thorny, one and a half times as broad as long. Pores regular, circular, hexagonally framed, as broad as the bars. Mouth slightly constricted. Apical horn stout and short, three-sided pyramidal. Three feet cylindrical, straight, divergent, twice to three times as long as the shell. (Similar to Lychnocanium favosum, Pl. 61, fig. 6, perhaps derived from it by reduction of the cephalis.)

Dimensions.—Shell 0.08 long, 0.12 broad; horn 0.02 long, feet 0.2 long.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

4. Tripilidium ovatum, n. sp.

Shell ovate, smooth, one and one half times as long as broad. Pores regular, circular, as broad as the bars. Mouth constricted, half as broad as the shell. Horn short, conical. Three feet conical, curved, convergent, scarcely one-third as long as the shell.

Dimensions.—Shell 0.15 long, 0.11 broad; horn 0.02 long, feet 0.04 long.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

5. Tripilidium clavatum, n. sp.

Shell nearly spherical, tuberculate, a little broader than long. Pores regular, circular, as broad as the bars. Mouth constricted, half as broad as the shell. Apical feet and the three divergent feet of equal size and similar form, about as long as the shell, straight, in the basal half smooth, cylindrical, in the distal half club-shaped, dimpled. (Very similar to Tripospyris conifera and Tripospyris eucolpos, Pl. 84, figs. 7 and 4; but the spherical shell exhibits no trace of sagittal ring or constriction, and the simple shell-cavity has a wide open mouth, and is not closed by a basal plate.)

Dimensions.—Shell 0.1 diameter, horn and feet 0.08 to 0.09 long.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

6. Tripilidium costatum, n. sp. (Pl. 98, figs. 8, 8a, 8b).

Shell ovate, spinulate and costate, nearly twice as broad as long. Surface with fifteen to twenty prominent longitudinal ribs, which are convergent towards each pole and elegantly denticulate. The deep furrows between them are divided by delicate, parallel, transverse ribs into numerous short and broad dimples (thirty to forty in each furrow); each dimple contains a small pore, like a transverse fissure. The apex bears a short and stout, three-sided pyramidal horn, the hollow base of which is closed by a small cortinar septum with three collar pores (fig. 8b). This seems to indicate a rudimentary cephalis and the derivation of this species from Lychnocanium (Pl. 61). Peristome constricted, only one-fourth as broad as the shell, with three short, conical, nearly vertical feet. The central capsule (fig. 8a) in the specimen examined was well preserved, hemispherical, not lobate, and filled up the upper half of the shell-cavity (beyond the rudiment of the cortinar septum).

Dimensions.—Shell 0.2 long, 0.12 broad; horn 0.01 long, feet 0.02 long.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

7. Tripilidium elongatum, n. sp.

Shell elongate, smooth, nearly cylindrical, in the upper third conical. Pores small and numerous, regular, circular, half as broad as the bars, disposed in about thirty longitudinal alternating rows. Peristome scarcely constricted. The apical horn and the three parallel feet are of equal size and similar form, straight, conical, one-sixth as long as the shell.

Dimensions.—Shell 0.12 long, 0.06 broad; horn and feet 0.02 long.

Habitat.—Fossil in Barbados.

Subgenus 2. Tripodocorys, Haeckel, 1881, Prodromus, p. 428.

Definition.—Feet forked or branched.

8. Tripilidium dichopodium, n. sp.

Shell hemispherical, nearly twice as broad as long, smooth. Pores irregular, roundish, twice to four times as broad as the bars. Mouth wide open. Apical horn spindle-shaped, half as long as the shell. Three feet cylindrical, nearly straight and parallel, as long as the shell, forked at the distal end. (Exhibits an external similarity to Tripospyris semantis, Pl. 84, fig. 2, but has no trace of sagittal ring and constriction, and the simple shell-cavity has a wide open mouth.)

Dimensions.—0.06 long, 0.1 broad; horn 0.03 long, feet 0.07 long.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

9. Tripilidium cladopodium, n. sp.

Shell campanulate, rough, about as long as broad. Pores subregular, circular, as broad as the bars. Mouth slightly constricted. Apical horn and three divergent feet of nearly equal size and form, three-sided prismatic, straight and stout, irregularly dentate and branched, somewhat longer than the shell.

Dimensions.—Shell 0.08 diameter; horn and feet 0.1 to 0.12 long.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 502. Tripodiscium,^[7] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) without lateral ribs and apical horn, with three simple or branched terminal feet.

The genus Tripodiscium may be derived either from the preceding Tripilidium by loss of the apical horn, or from the nearly related Tristylospyris by loss of the sagittal ring and constriction. Some forms of the latter genus can scarcely be distinguished from similar species of the former.

Subgenus 1. Tripodiscinus, Haeckel.

Definition.—Feet simple, not branched nor forked.

1. Tripodiscium tristylospyris, n. sp.

Shell subspherical, with regular, circular pores, twice as broad as the bars. Mouth constricted, half as broad as the shell, with three short spindle-shaped feet, which are nearly parallel and vertical, half as long as the shell. (Similar to Tristylospyris scaphipes, Pl. 84, fig. 13, but without sagittal ring and constriction.)

Dimensions.—Shell 0.08 long, 0.07 broad; feet 0.04 long.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Tripodiscium ovatum, n. sp.

Shell ovate, rough, nearly as broad as long. Pores regular circular, double-contoured, twice as broad as the bars. Mouth constricted, one-third as broad as the shell, with three convergent short triangular feet.

Dimensions.—Shell 0.1 long, 0.09 broad; feet 0.02 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

3. Tripodiscium clavatum, n. sp.

Shell ovate, smooth, one and a half times as long as broad. Pores irregular roundish, of different sizes. Mouth constricted, two-thirds as broad as the shell, with three divergent, straight club-shaped feet, nearly as long as the shell.

Dimensions.—Shell 0.12 long, 0.08 broad; feet 0.1 long.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

4. Tripodiscium campanula, Haeckel.

Carpocanium campanula, Stöhr, 1880, Palæontogr., vol. xxvi. p. 96, Taf. iii. fig. 9.

Shell campanulate or subspherical, smooth, about as long as broad. Pores small, regular circular, as broad as the bars. Mouth constricted, about half as broad as the shell, with three short conical descending feet.

Dimensions.—Shell 0.06 long, 0.05 broad; feet 0.02 long.

Habitat.—North Pacific, Station 244, depth 2900 fathoms; fossil in Sicily.

Subgenus 2. Tripodisculus, Haeckel.

Definition.—Feet branched or forked.

5. Tripodiscium furcatum, n. sp.

Shell ovate, rough, nearly as broad as long. Pores subregular, circular, twice as broad as the bars. Mouth constricted, two-thirds as broad as the shell, with three divergent parallel and vertical feet, which are as long as the shell, and forked at the distal end.

Dimensions.—Shell 0.09 long, 0.08 broad; feet 0.07 long.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.

6. Tripodiscium ramosum, n. sp.

Shell ovate, tuberculate, nearly as broad as long. Pores irregular, roundish, of very different sizes. Mouth constricted, half as broad as the shell, with three large, divergent, irregularly branched feet, nearly twice as long as the shell. (Similar to Tristylospyris ramosa, Pl. 52, fig. 23, but without sagittal ring and constriction.)

Dimensions.—Shell 0.07 long, 0.06 broad; feet 0.15 long.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

7. Tripodiscium sphærocephalum, n. sp. (Pl. 52, fig. 21).

Shell subspherical, rough, with circular pores of different sizes. Mouth constricted, circular, simple, two-thirds as broad as the shell, with three large divergent feet, which are three-sided prismatic, irregularly branched, and twice as long as the shell.

Dimensions.—Shell 0.07 long, 0.08 broad; feet 0.12 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Genus 503. Tridictyopus,^[8] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three latticed terminal feet. Shell ovate or subconical, with an apical horn.

The genus Tridictyopus differs from the nearly allied Tripilidium in the possession of three large fenestrated shovel-shaped feet, forming direct prolongations of the large conical shell. The lattice work exhibits a peculiar elegant structure recurring in the similar, perhaps nearly related, Cephalospyris (Pl. 83, fig. 10; Pl. 96, fig. 28). The central capsule is large, ellipsoidal or ovate, and fills up the greater part of the shell cavity (compare R. Hertwig, 1879, loc. cit., p. 75).

1. Tridictyopus vatillum, n. sp. (Pl. 51, fig. 8).

Shell campanulate, about as long as broad (excluding horn and feet). Pores irregular, polygonal, in the middle part more regular, triangular. Horn short and stout, three-sided pyramidal. Three feet large, triangular, shovel-shaped, about half as long as the shell.

Dimensions.—Shell 0.14 long, 0.15 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

2. Tridictyopus conulus, n. sp. (Pl. 51, fig. 7).

Shell campanulate conical, about one and a half times as long as broad (excluding horn and feet). Pores mostly triangular, disposed in subregular hexagonal figures, which are separated by bands of smaller irregular polygonal pores. Horn short and stout, three-sided pyramidal. Three feet triangular shovel-shaped, convergent, about one-sixth as long as the shell.

Dimensions.—Shell 0.3 long, 0.2 broad; horn 0.04 long, feet 0.05 long.

Habitat.—Equatorial Atlantic, Station 347, depth 2250 fathoms.

3. Tridictyopus elegans, R. Hertwig.

Tridictyopus elegans, R. Hertwig, 1879, Organismus d. Radiol., p. 75, Taf. vii. fig. 3, 3a, 3b.

Shell slender, conical, campanulate, about twice as long as broad (excluding horn and feet). Most pores subregular triangular, with some irregular polygonal ones intermingled. The horn in the two observed specimens was broken off, together with the conical apex of the shell. Three feet triangular shovel-shaped, about one-sixth as long as the shell.

Dimensions.—Shell 0.3 long, 0.15 broad; feet 0.05 long.

Habitat.—Mediterranean (Messina), R. Hertwig, surface.

Subfamily 2. Archiperida, Haeckel, 1881, p. 429.

Definition.—Tripocalpida with the basal mouth of the shell fenestrated (vel Monocyrtida triradiata clausa).

Genus 504. Euscenium,^[9] n. gen.

Definition.—Archiperida (vel Monocyrtida triradiata clausa) with a free simple internal columella, prolonged into an apical horn. Three basal feet free, without lateral wings.

The genus Euscenium and the three following nearly allied genera form together the remarkable small group of Euscenida, probably one of the oldest and most primitive of all Cyrtoidea, and perhaps the common root of this suborder, arising directly from the Plectoidea. The simple skeleton is composed of four radial beams united in one point (the cortinar centrum). Three beams are directed downwards, and form three divergent basal feet; the fourth beam is directed upwards and represents an apical horn; its basal part is enclosed as "columella" in the cavity of the simple shell, the lattice-work of which connects the four spines (compare above, Plectaniscus, p. 924). In the genus Euscenium, the simplest of all, the columella is simple, and the three feet also simple, without wings.

Subgenus 1. Euscenarium, Haeckel.

Definition.—Three feet simple, not branched.

1. Euscenium plectaniscus (Pl. 98, fig. 1).

Shell three-sided pyramidal, thorny, about as long as broad, with three dentate edges. Framework very loose, with irregular polygonal meshes; in the middle of each of the three triangular sides a horizontal band of denser network. Basal plate with three very large simple collar-holes. The apical horn and the three feet are three-sided pyramidal, about half as long as the columella, with three prominent irregularly dentate edges. The horn is straight, whilst the three feet are hook-shaped, its distal end being curved downwards and inwards.

Dimensions.—Shell 0.11 long, 0.13 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

2. Euscenium archicyrtis, n. sp.

Shell three-sided pyramidal, smooth, nearly as long as broad, with three straight edges connected by irregular loose framework with polygonal meshes. Basal plate with three very large simple collar-holes. The apical horn and the three feet are three-sided prismatic, smooth, about twice as long as the columella, straight and widely divergent.

Dimensions.—Shell 0.08 long, 0.1 broad.

Habitat.—Tropical Pacific, Station 225, depth 4475 fathoms.

3. Euscenium hemisphæricum, n. sp.

Shell hemispherical smooth, half as long as broad, with small and numerous subregular circular pores. Basal plate with three large triangular simple collar-holes. Horn slender, three-sided prismatic, twice as long as the columella. Feet very slender, with three denticulate edges, widely divergent and curved like the quadrant of a circle.

Dimensions.—Shell 0.04 long, 0.06 broad.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

4. Euscenium tricolpium, n. sp. (Pl. 53, fig. 12).

Archiscenium tricolpium, Haeckel, 1881, Prodromus et Atlas, loc. cit.

Shell cap-shaped, nearly hemispherical, with three vaulted hemispherical bosoms between the three arches ascending from the feet to the horn. Network very irregular, with polygonal meshes, of different form and size. Basal plate with three large primary and some smaller irregular accessory collar-holes. Horn slender, straight, twice as long as the columella. Feet of the same length, slender, widely divergent, slightly curved. The three edges of the horn and the feet are elegantly denticulated.

Dimensions.—Shell 0.04 long, 0.08 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

5. Euscenium tripospyris, n. sp. (Pl. 84, fig. 8).

Tripospyris euscenium, Haeckel, 1881, Prodromus et Atlas.

Shell nearly spherical, smooth, with numerous small circular pores. Basal plate also with numerous small pores. Horn and feet stout, three-sided prismatic, straight or slightly curved, about as long as the thin, somewhat curved columella. This species is closely allied to Tripospyris.

Dimensions.—Shell 0.11 to 0.12 diameter, horn and feet 0.08 to 0.1 long.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

Subgenus 2. Euscenidium, Haeckel.

Definition.—Feet forked or branched.

6. Euscenium furcatum, n. sp.

Shell campanulate, smooth, with numerous irregular roundish pores. Basal plate with nine pores (three larger central and six smaller distal). Horn club-shaped, half as long as the columella. Feet twice as long, cylindrical, parallel, vertical, forked at the distal end. (Similar to Tripospyris semantis, Pl. 84, fig. 2, but without sagittal feet.)

Dimensions.—Shell 0.07 long, 0.06 broad; horn 0.04 long, feet 0.1 long.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

7. Euscenium quadratum, n. sp.

Shell campanulate, smooth with subregular square pores. Basal plate with three large pores. Horn and feet of the same size and shape, twice as long as the columella, three-sided prismatic, each with four or five verticils of lateral branches. (Similar to the cephalis of Clathrocorys murrayi, Pl. 64, fig. 8, but with four free spines without connecting lattice-wings.)

Dimensions.—Shell 0.06 long, 0.05 broad; horn and feet 0.12 long.

Habitat.—Central Pacific, Station 272, surface.

8. Euscenium ramosum, n. sp.

Shell subspherical, rough, with small subregular circular pores. Basal plate with nine pores (three larger central and six smaller distal pores). Horn and feet of the same size and form, three to four times as long as the columella, three-sided prismatic, irregularly branched.

Dimensions.—Shell 0.06 diameter, horn and feet 0.15 to 0.2 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 505. Cladoscenium,^[10] Haeckel, 1881, Prodromus, p. 429.

Definition.—Archiperida (vel Monocyrtida triradiata clausa) with a free branched internal columella, prolonged into an apical horn. Three basal feet free, without lateral wings.

The genus Cladoscenium differs from the preceding Euscenium only in the ramification of the internal columella, which bears one or more verticils of three ascending lateral branches. The three branches of each verticil lie in the same equidistant meridian planes as the three basal feet, and are inserted with their distal ends on the inner surface of the simple lattice-shell. The three feet are also branched, but without vertical lattice-wings. Cladoscenium is perhaps closely allied to Clathrocorys.

1. Cladoscenium fulcratum, n. sp.

Shell subspherical, smooth, with large irregular roundish pores. Basal plate with three large pores. Columella with a single verticil of three ascending lateral branches. Apical horn as long as the columella, simple, three-sided prismatic. Feet twice as long, widely divergent, straight, prismatic, with some irregular basal branches.

Dimensions.—Shell 0.06 diameter, horn 0.05 long, feet 0.1 long.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Cladoscenium ancoratum, n. sp. (Pl. 53, fig. 13).

Shell campanulate, smooth, with irregular polygonal pores. Basal plate with six pores (two large cardinal, two smaller jugular and two still smaller cervical pores). Columella with a single verticil of three ascending lateral branches (by mistake not distinct in the figure). Apical horn and the three feet of the same form and size, slender, prismatic, twice to three times as long as the shell, straight, in the distal half with three slender recurved branches, anchor-shaped.

Dimensions.—Shell 0.05 long, 0.04 broad; horn and feet 0.1 to 0.15 long.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

3. Cladoscenium gladiatum, n. sp.

Shell subspherical, with irregular polygonal pores. Basal plate with three large pores. Columella with two verticils of three ascending lateral branches. Apical horn as long as the columella, three-sided prismatic. Feet of the same form, twice as long, in the distal half with two opposite transverse branches, sword-shaped.

Dimensions.—Shell 0.05 long, 0.06 broad; horn 0.04 long, feet 0.1 long.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

4. Cladoscenium pinnatum, n. sp.

Shell campanulate, with irregular polygonal pores. Basal plate with four pores (two major cardinal and two minor jugular). Columella with two verticils of three ascending lateral branches, and prolonged into a slender prismatic apical horn of twice the length, which bears four such verticils. Feet twice as long as the horn, pinnate, each with four or five pairs of opposite lateral branches, decreasing towards the thin distal end.

Dimensions.—Shell 0.06 long, 0.05 broad; horn 0.1 long, feet 0.2 long.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

5. Cladoscenium verticillatum, n. sp.

Shell campanulate, with subregular square pores. Basal plate with nine pores (three larger central and six smaller distal). Columella with three verticils of three ascending lateral branches. Apical horn and the three basal feet of equal size and similar form, four to six times as long as the columella, three-sided prismatic, each with four to five verticils of three lateral branches, which are irregularly ramified and tapering towards the distal end. (Similar to Clathrocorys teuscheri, Pl. 64, fig. 10, but with four free spines, without connecting lattice-wings.)

Dimensions.—Shell 0.07 long, 0.06 broad; horn and feet 0.2 to 0.25 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

6. Cladoscenium pectinatum, n. sp. (Pl. 98, fig. 2).

Shell subspherical, with irregular roundish pores. Basal plate with three large holes. Columella with two verticils of three ascending lateral branches. Apical horn and the three feet of nearly the same size and form, three to four times as long as the columella, straight, three-sided prismatic, each with five to eight verticils of three simple lateral branches, tapering towards the distal end.

Dimensions.—Shell 0.07 long, 0.08 broad; horn and feet 0.16 to 0.22 long.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

Genus 506. Archiscenium,^[11] Haeckel, 1881, Prodromus, p. 429.

Definition.—Archiperida (vel Monocyrtida triradiata clausa) with a free simple internal columella, prolonged into an apical horn. Three basal feet connected with the horn by three vertical lateral wings.

The genus Archiscenium and the following nearly allied Pteroscenium are derived from the two preceding genera, from which they differ in the development of three free vertical lateral lattice-wings; these arise from the upper edge of the three basal feet and connect them with the three edges of the apical horn. The basal part of the latter, enclosed in the shell, forms an internal free columella, which in Archiscenium is simple, not branched.

1. Archiscenium quadrispinum, n. sp. (Pl. 53, fig. 11).

Shell hemispherical, smooth, with a small number of large irregular polygonal meshes and thin bars. Basal lattice with three very large central meshes and six smaller peripheral meshes (two on the base of each foot). Apical horn and the three feet of equal size and similar form, slender, pyramidal, widely divergent, straight, as long as the shell-diameter. Three lateral wings small, little prominent, each with two or three irregular meshes. Central capsule subspherical.

Dimensions.—Shell 0.05 long, 0.1 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

2. Archiscenium clathrocorys, n. sp.

Shell campanulate, smooth, with numerous irregular square meshes. Basal lattice with three very large meshes. Apical horn and the three feet of equal size and similar form, three-sided prismatic, widely divergent, straight, twice as long as the shell-diameter. Three lateral wings broad, each with a basal row of few very large irregular roundish meshes, and several distal rows of small square meshes. This species is very similar to Clathrocorys murrayi (Pl. 64, fig. 8), but has no trace of thorax-wall. The latter species may be derived from the former by development of the thoracic lattice, which connects the three free feet.

Dimensions.—Shell 0.05 long, 0.06 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

3. Archiscenium tripterygium, n. sp.

Shell hemispherical, smooth, with numerous irregular roundish meshes of very different sizes. Basal lattice with four large meshes, two major cardinal and two minor cardinal pores. Apical horn and the three feet of similar form and size, slender prismatic, three to four times as long as the shell; the horn straight, the feet curved. Three lateral wings very delicate, with a basal row of few large irregular polygonal meshes, and several distal rows of similar small pores.

Dimensions.—Shell 0.04 long, 0.05 broad.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

4. Archiscenium cyclopterum, n. sp. (Pl. 98, fig. 3).

Shell hemispherical, with small irregular roundish pores. Basal lattice with four large meshes, two major cardinal and two minor jugular pores. Apical horn and the three feet of similar form and size, slender prismatic, straight, twice to four times as long as the shell. Three lateral wings nearly semicircular, densely latticed, with the same pores as the shell, and smooth convex margin.

Dimensions.—Shell 0.05 long, 0.06 broad.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

5. Archiscenium callimitra, n. sp.

Shell campanulate, with irregular polygonal pores. Basal lattice with nine meshes (three larger central and six smaller distal pores, as in Callimitra carolotæ, Pl. 63, fig. 8). Apical horn straight, prismatic, slender, conical, twice as long as the shell. Feet longer and more slender, slightly curved. Three lateral wings very broad, densely fenestrated, with irregular polygonal pores of the same shape as in the similar Callimitra carolotæ (Pl. 63, fig. 1).

Dimensions.—Shell 0.05 long, 0.04 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 507. Pteroscenium,^[12] Haeckel, 1881, Prodromus, p. 429.

Definition.—Archiperida (vel Monocyrtida triradiata clausa) with a free branched internal columella, prolonged into an apical horn. Three basal feet connected with the horn by three vertical lateral wings.

The genus Pteroscenium differs from the preceding Archiscenium only in the ramification of the internal columella, and therefore exhibits to it the same relation that Cladoscenium bears to Euscenium. The branches of the columella form also here verticils of ascending branches, three in each verticil, and their distal ends are inserted on the inner surface of the lattice-shell.

1. Pteroscenium arcuatum, n. sp. (Pl. 98, fig. 4).

Shell campanulate, smooth, nearly conical, somewhat broader than long, with irregular dense network of small circular pores. Columella straight, with two or three triradiate verticils of horizontal lateral branches, which are inserted in the shell-wall. Horn slender pyramidal, as long as the shell. Three divergent feet twice as long as the horn, strongly curved, thorny, three-edged; the distance of their pointed ends twice as broad as the shell. From the outer edge of each foot arise numerous ascending bristles, which are connected together and with similar lateral branches of the horn by curved arches, forming three delicate spiny vertical wings.

Dimensions.—Shell 0.06 long, 0.08 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Pteroscenium arcadophorum, n. sp.

Shell campanulate, smooth, with irregular polygonal pores, very similar to the preceding species but with much broader wings, forming several arcades with three to five rows of irregular meshes. Columella with five or six triradiate verticils of lateral branches. Horn twice as long as the shell, of the same length as the strongly curved spinulate feet.

Dimensions.—Shell 0.09 long, 0.11 broad.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Pteroscenium pinnatum, n. sp. (Pl. 53, figs. 14, 15, 16).

Shell campanulate, smooth, somewhat longer than broad, with irregular delicate network of small roundish pores. Columella straight, with numerous (eight to twelve) triradiate verticils of ascending lateral branches, which are inserted in the shell-wall. The uppermost end of the columella is a conical apical horn. The three divergent feet are smooth, slender, conical, slightly curved, about as long as the shell, pinnate, with six to ten pairs of ascending lateral branches, parallel to those of the columella and inserted on the three vaulted lateral wings. (Fig. 14 exhibits the outside of the shell, fig. 15 the internal structure of the cortina, fig. 16 the basal view.)

Dimensions.—Shell 0.1 long, 0.12 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

4. Pteroscenium spinulosum, n. sp.

Shell campanulate, spinulate, about as long as broad, with small and numerous irregular polygonal pores, very similar to the preceding species, but differing in the more slender form of the horn and the feet, bearing more numerous lateral branches (twelve to sixteen pairs on each foot). Columella with six to eight triradiate verticils. Horn about as long as the shell.

Dimensions.—Shell 0.1 long, 0.1 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

5. Pteroscenium macropodium, n. sp.

Shell campanulate, spinulate, with irregular polygonal pores; very similar to the two preceding species, but differing in the size and shape of the three feet, which are for the most part solid, triangular, nearly parallel, vertical, very slender, three times as long as the shell, latticed only at the curved base, with few pairs of lateral branches. Columella with four to six triradiate verticils, as long as the stout triangular pyramidal horn.

Dimensions.—Shell 0.1 long, 0.08 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

6. Pteroscenium tripocolpum, n. sp.

Shell campanulate, spinulate, similar to Euscenium tricolpium (Pl. 53, fig. 12) with three vaulted hemispherical bosoms between the three delicate arachnoidal vertical wings. Network loose, very irregular, with polygonal meshes of very different sizes. Columella with three or four triradiate verticils, as long as the slender pyramidal horn. Three feet twice as long, somewhat curved, widely divergent, with three or four pairs of lateral branches. The three edges of the feet and of the horn are elegantly denticulated.

Dimensions.—Shell 0.06 long, 0.09 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 508. Peridium,^[13] Haeckel, 1881, p. 429.

Definition.—Archiperida (vel Monocyrtida triradiata clausa) without internal columella, with an apical horn.

The genus Peridium (or Archiperidium, Prodromus, loc. cit.) and the two following nearly allied genera form together the small group of Archibursida, differing from the four preceding genera (the Euscenida) in the absence of an internal free columella. The three basal feet have therefore no direct connection with the apical horn. Peridium, the ancestral form of the Archibursida, may have originated either from Euscenium by reduction and loss of the columella, or directly from Tripospyris by loss of the sagittal ring and the longitudinal constriction.

Subgenus 1. Peridarium, Haeckel.

Definition.—Feet smooth, simple, neither spiny nor branched.

1. Peridium lasanum, n. sp.

Shell subspherical, smooth, with subregular circular pores. Basal plate with three large meshes. Horn apical, vertical, of the same size and form as the three divergent smooth feet, slender pyramidal, twice to three times as long as the shell.

Dimensions.—Shell-diameter 0.06 to 0.07, length of the three spines 0.15 to 0.2.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

2. Peridium papillatum, n. sp.

Shell subspherical, papillate, with subregular circular pores. Basal plate with four meshes (two major cardinal and two minor jugular pores). Horn occipital, oblique, three-sided pyramidal, half as long as the shell and as the three widely divergent, subhorizontal, smooth feet.

Dimensions.—Shell diameter 0.07 to 0.08, length of the horn 0.04, of the feet 0.08.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Peridium curvipes, n. sp.

Shell hemispherical, thorny, with irregular roundish pores. Basal plate with six pores (two larger middle cardinal, two smaller anterior jugular and two smaller posterior cervical pores, as in Pl. 53, figs. 13, 18). Horn conical, oblique, arising from the middle of the occipital face, half as long as the shell. Feet slender, conical, curved, smooth, twice as long as the shell.

Dimensions.—Shell 0.04 long, 0.06 broad; horn 0.02 long; feet 0.08 long.

Habitat.—Tropical Pacific, Station 206, depth 2100 fathoms.

Subgenus 2. Archiperidium, Haeckel.

Definition.—Feet spiny or branched.

4. Peridium spinipes, n. sp. (Pl. 53, fig. 9).

Shell ovate, rough or thorny, with irregular roundish pores. Basal plate with four pores (two larger cardinal and two smaller jugular pores). Horn oblique, occipital, three-sided pyramidal, half as long as the shell, connected with the caudal foot by a prominent crest. Three feet horizontally expanded, prismatic, spiny, about as long as the shell.

Dimensions.—Shell 0.08 long, 0.06 broad; horn 0.04 long, feet 0.06 to 0.09 long.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

5. Peridium palmipes, n. sp. (Pl. 53, fig. 10).

Shell ovate, smooth, with irregular roundish pores. Basal plate with three large pores. Horn oblique, three-sided pyramidal, about as long as the shell, inserted near its occipital base. Three feet prismatic, slender, half as long, ending with a broad dentate plate.

Dimensions.—Shell 0.06 long, 0.05 broad; horn 0.05 long, feet 0.03 long.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

6. Peridium alatum, n. sp. (Pl. 97, fig. 7).

Shell subspherical smooth, with regular circular, hexagonally-framed pores. Basal plate with nine pores (three larger central and six smaller distal pores). Horn apical, of equal size and the same form as the three feet, three-sided prismatic, with three broad prominent wings, somewhat longer than the shell.

Dimensions.—Shell 0.07 long, 0.08 broad; horn and feet 0.1 to 0.12 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

7. Peridium cervinum, n. sp.

Shell subspherical, spiny, with subregular circular pores. Basal plate with four pores (?). Horn apical, conical, about as long as the shell. Feet three to four times as long, cylindrical curved, with irregular simple or forked branches like the antlers of a deer.

Dimensions.—Shell diameter 0.1, horn 0.1 long, feet 0.3 to 0.4 long.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 509. Archipera,^[14] Haeckel, 1881, Prodromus, p. 429.

Definition.—Archiperida (vel Monocyrtida triradiata clausa) without internal columella, with two or more apical horns.

The genus Archipera differs from the preceding Peridium only in the multiplication of the apical horn, which in the latter is always simple. The number of horns is usually two or three, sometimes four or more. The species bearing three horns may be derived directly from Triceraspyris by loss of the sagittal ring.

1. Archipera cortiniscus, n. sp. (Pl. 98, fig. 5).

Shell ovate, thorny, with large roundish pores, which are closed by sieve-plates with numerous small porules. Basal plate with two pairs of simple large pores (two smaller jugular and two larger cardinal, similar to Pl. 98, fig. 10b). Two horns divergent, curved, slender, pyramidal; the apical horn longer than the shell, the frontal horn shorter. Three feet divergent, longer than the shell, three-sided prismatic, at the distal end club-shaped, thorny.

Dimensions.—Shell 0.1 long, 0.08 broad; horns and feet 0.11 to 0.14 long.

Habitat.—Tropical Pacific, Station 225, depth 4475 fathoms.

2. Archipera pentacantha, n. sp.

Shell pear-shaped, smooth, with numerous and small irregular roundish pores. Basal plate with three larger pores. Two horns and three feet of nearly equal size and similar form, three-sided prismatic, about as long as the shell diameter, somewhat curved. The apical horn stands on the apex, the frontal horn half-way up the shell.

Dimensions.—Shell 0.08 long, 0.06 broad; horns and feet 0.05 to 0.07 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Archipera bicornis, n. sp.

Shell ovate, rough, with small regular circular, sparsely scattered pores. Basal plate with four larger central and a peripheral coronal of twelve smaller pores. Two horns near the apex widely divergent, somewhat shorter than the shell, of equal size and similar form. Three feet twice as long, horizontally expanded. All five spines slender, three-sided pyramidal, straight.

Dimensions.—Shell 0.07 long, 0.06 broad; horns 0.05 long, feet 0.1 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

4. Archipera tricornis, n. sp.

Shell subspherical, smooth, with subregular circular pores. Basal plate with four large meshes (two major cardinal and two minor jugular pores). On the apex three divergent pyramidal horns of different size, one larger occipital and two smaller frontal horns. Three feet prismatic, about twice as long as the shell.

Dimensions.—Shell diameter 0.05, length of the feet 0.1.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

5. Archipera quadricornis, n. sp.

Shell ovate, smooth, with a small number of irregular roundish, widely scattered pores. Basal plate with four crossed meshes of nearly equal size. On the equator there arise four divergent prismatic horns of nearly equal size, three of which correspond to the three feet, whilst the fourth is opposite to the caudal foot. The three feet are also prismatic, as long as the shell, horizontally expanded. (Similar to the upper half of Lithomelissa decacantha, Pl. 56, fig. 2, but without thorax.)

Dimensions.—Shell 0.05 long, 0.04 broad; horns and feet 0.06 long.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

6. Archipera multicornis, n. sp.

Shell hemispherical, spiny, with irregular polygonal pores. Basal plate with six meshes (?). Between the smaller spines of the surface arise six larger conical divergent horns. Three feet also conical, divergent, about twice as long as the shell and the horns.

Dimensions.—Shell 0.05 long, 0.07 broad; horns 0.05 long, feet 0.1 long.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 510. Archibursa,^[15] Haeckel, 1881, Prodromus, p. 429.

Definition.—Archiperida (vel Monocyrtida triradiata clausa) without internal columella and without apical horn.

The genus Archibursa has probably arisen from Peridium by loss of the apical horn, and is the only genus of Archiperida which bears no horn. The three basal feet are well-developed. It differs from the similar Tristylospyris by the absence of the sagittal ring and the corresponding longitudinal constriction.

1. Archibursa tripodiscus, n. sp. (Pl. 98, fig. 6).

Shell subspherical, smooth, with irregular roundish pores. Basal plate with three large triangular pores of equal size (fig. 6). Three feet widely divergent, straight, three-sided prismatic, about as long as the diameter of the shell.

Dimensions.—Diameter of the shell 0.07, length of the feet 0.09.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Family LX. Phænocalpida, n. fam.

Archiphormida et Archiphænida, Haeckel, 1881, Prodromus, pp. 428, 429.

Definition.—Monocyrtida multiradiata. (Cyrtoidea with a simple, not jointed shell, resembling a simple cephalis, with numerous radial apophyses (four to nine or more).

The family Phænocalpida, composed of the Archiphormida and Archiphænida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is quite without transverse constriction, but bears numerous radial apophyses. The two subfamilies differ in the shape of the basal mouth, which in the Archiphormida is a simple wide opening, but is closed in the Archiphænida by a lattice-plate.

Several Phænocalpida were formerly described by Ehrenberg, viz., Halicalyptra virginica (in 1844) and Litharachnium arachnodiscus (in 1872, called by him Carpocanium, though it is quite different from this genus, and closely allied to my Litharachnium tentorium, figured in 1862). These forms belong to the Archiphormida (with open mouth). Several fossil Archiphænida (with closed mouth) were figured by Ehrenberg, in 1875, as belonging to Petalospyris (ocellata, carinata, flabellum), though the absence of the sagittal ring and the corresponding longitudinal constriction demonstrates their character as Phænocalpis.

The Phænocalpida are probably an artificial family, composed of three or four (or perhaps more) different groups, which have a quite different origin. The Litharachnida (genera 511-515) and the Haliphormida (genera 516-518) are probably derived from the Sethophormida by loss of the cephalis, the retrograde metamorphosis of which may be observed in all its different stages. The Halicalyptrida (genera 519-521) are perhaps independent of the other Phænocalpida, and may be Archicorida which have produced a corona of teeth around the mouth, without relation to lost radial ribs. The Phænoscenida (Phænocalpis, Phænoscenium) may be derived from the Euscenida (genera 504-507) by interpolation of interradial feet between the three primary ones, or directly from the Plectoidea. The Calpophænida, on the other hand (Calpophæna, Archiphæna), may have arisen from the Zygospyrida (Petalospyris, Gorgospyris) by loss of the sagittal ring and the longitudinal constriction. The phylogeny of the Phænocalpida is therefore a very complicated problem, as yet unsolved.

Synopsis of the Genera of Phænocalpida.

I. Subfamily Archiphormida. Basal mouth of the shell a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Radial ribs enclosed in the wall of the shell, usually prolonged into free terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell slender, pyramidal (without horn).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell simple, with simple network,			511. Bathropyramis.
						Shell simple, with double network,			512. Cinclopyramis.
						Shell double, with an outer mantle,			513. Peripyramis.
				Shell flatly campanulate or discoidal (without horn).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Radial ribs simple,			514. Litharachnium.
						Radial ribs branched,			515. Cladarachnium.
				Shell ovate, urceolate or campanulate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Mouth smooth, constricted (no horn),			516. Cystophormis.
						Mouth, with a corona of feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	With horn,	517. Haliphormis.
								No horn,	518. Archiphormis.
		No radial ribs in the wall of the shell. Mouth surrounded by a corona of free terminal feet.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell simple without mantle.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	With horn,	519. Halicalyptra.
								No horn,	520. Carpocanistrum.
						Shell double, with an external mantle (no horn),			521. Arachnocalpis.
II. Subfamily Archiphænida. Basal mouth closed by a lattice-plate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	In the axis of the shell-cavity a free columella.			$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Columella simple,			522. Phænocalpis.
						Columella branched,			523. Phænoscenium.
		Shell-cavity simple, without axial columella.			$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Apex with a horn,			524. Calpophæna.
						No apical horn,			525. Archiphæna.

Subfamily 1. Archiphormida, Haeckel, 1881, Prodromus, p. 428.

Definition.—Phænocalpida with the basal mouth of the shell open (vel Monocyrtida multiradiata aperta).

Genus 511. Bathropyramis,^[16] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archiphormida (vel Monocyrtida multiradiata aperta) with simple, slender pyramidal shell and numerous radial beams (six to nine or more). Network simple, with large, unfenestrated, quadrangular meshes.

The genus Bathropyramis and the following four nearly allied genera form together a peculiar group of Archiphormida, the Litharachnida, possessing near relations to Sethopyramis and the allied Sethophormida, from which they are probably derived by reduction and loss of the small cephalis. The shell in all these forms is distinctly pyramidal, composed of numerous divergent radial beams (commonly six to nine), which form the edges of the pyramid, and are connected by parallel horizontal rings. The quadrangular meshes so produced are quite simple in Bathropyramis. This genus cannot be sharply separated from Sethopyramis, its ancestral form.

Subgenus 1. Acropyramis, Haeckel, 1881, Prodromus, p. 428.

Definition.—Shell smooth, without spines on the surface.

1. Bathropyramis acephala, n. sp.

Shell smooth, slenderly pyramidal, with three cortinar pores at the apex and with six stout radial beams or longitudinal ribs, connected by twelve to sixteen complete hexagonal horizontal rings. Meshes nearly square, increasing gradually in size towards the mouth.

Dimensions.—Shell 0.25 long, 0.15 broad.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

2. Bathropyramis quadrata, n. sp. (Pl. 54, fig. 1).

Shell smooth, slenderly pyramidal, with three cortinar pores at the apex and nine stout radial beams, connected by eight to twelve complete circular horizontal rings. Meshes subregular, square, increasing in size gradually towards the circular mouth.

Dimensions.—Shell 0.2 to 0.3 long, 0.12 to 0.2 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Bathropyramis trapezoides, n. sp. (Pl. 54, fig. 3).

Shell smooth, broadly pyramidal, with four cortinar pores at the apex and eight (or sometimes nine) stout radial beams, connected by twelve to sixteen complete octagonal horizontal rings. Meshes trapezoidal, of nearly equal length, but gradually increasing in breadth.

Dimensions.—Shell 0.3 long, 0.3 broad.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

4. Bathropyramis interrupta, n. sp. (Pl. 55, fig. 7).

Shell smooth, flatly pyramidal, nearly discoidal, with four cortinar pores at the apex and nine to ten stout radial beams, connected by eight to sixteen interrupted rings; the rings are complete only in the apical part, in the distal part more or less irregularly interrupted.

Dimensions.—Shell 0.12 long, 0.36 broad.

Habitat.—North Atlantic, Station 354, surface.

5. Bathropyramis medusa, n. sp.

Shell smooth, flatly pyramidal, nearly discoidal, with four cortinar pores and numerous radial beams (thirty to fifty); the four perradial of these are prolongations of the four cortinar beams, and alternate with four interradial of the same size. Between these are intercalated eight adradial beams arising from the third ring; and between the former and the latter, sixteen to twenty-four peripheral radial beams, arising from the fourth to the sixth ring. The inner four to six rings are complete, the outer ten to fifteen irregularly interrupted.

Dimensions.—Shell 0.08 long, 0.3 to 0.4 broad.

Habitat.—South Atlantic, Station 338, surface.

Subgenus 2. Cladopyramis, Haeckel, 1881, Prodromus, p. 428.

Definition.—Shell spiny, with prominent simple or branched spines on the surface.

6. Bathropyramis spinosa, n. sp.

Shell spiny, slenderly pyramidal, with three cortinar pores at the apex and with nine strong radial beams, connected by fifteen to twenty complete parallel rings. Meshes subregular square, increasing gradually in size. Surface covered with simple, strong conical spines, arising from the nodal points.

Dimensions.—Shell 0.24 long, 0.16 broad.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

7. Bathropyramis ramosa, n. sp. (Pl. 54, fig. 4).

Shell spiny, slenderly pyramidal, with three cortinar pores at the apex, and with nine (or sometimes eight or ten) strong radial beams, connected by fifteen to eighteen complete parallel rings. Meshes subregular, square, increasing gradually in size. Surface covered with forked or irregularly branched spines, arising from the nodal points.

Dimensions.—Shell 0.3 long, 0.17 broad.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

Genus 512. Cinclopyramis,^[17] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archiphormida (vel Monocyrtida multiradiata aperta) with simple, slender, pyramidal shell, and numerous radial beams (six to nine or more). Network double, with a delicate arachnoidal fenestration, filling up the large quadrangular meshes.

The genus Cinclopyramis differs from the preceding Bathropyramis in the development of a very delicate secondary network, filling up the large quadrangular meshes, which are produced by the crossing of the radial beams and the parallel horizontal rings. It therefore bears the same relation to the preceding genus that Plectopyramis does to Sethopyramis; it is perhaps derived directly from the former by loss of the small cephalis.

1. Cinclopyramis cribellum, n. sp.

Cinclopyramis cribellum = "Ladder of lattice-shape," Bury, 1862, Polycystins of Barbados, pl. xii. fig. 6.

Shell slender, pyramidal, with six strong radial ribs, which are connected by twelve to sixteen complete horizontal rings. Meshes trapezoidal, filled up by a very delicate and regular secondary network with square porules (two to four horizontal threads in each larger mesh).

Dimensions.—Shell 0.2 to 0.3 long, 0.12 to 0.16 broad.

Habitat.—Fossil in Barbados.

2. Cinclopyramis infundibulum, n. sp. (Pl. 54, fig. 7).

Shell slender, pyramidal, with nine strong radial ribs, which are connected by eighteen to twenty-four complete horizontal rings. Meshes subregular square, filled up by a very delicate and regular secondary network with square porules (ten to twelve horizontal threads in each larger mesh). Apex of the pyramid with three very small cortinar pores.

Dimensions.—Shell 0.3 to 0.4 long, 0.2 to 0.25 broad.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.

3. Cinclopyramis lithosestrum, n. sp.

Shell slender, pyramidal, with twelve strong radial ribs (six primary longer and six secondary shorter) connected by twelve to fifteen interrupted irregular rings. Meshes irregular square or trapezoidal, filled up by a delicate secondary network with irregular polygonal porules.

Dimensions.—Shell 0.4 to 0.5 long, 0.2 to 0.3 broad.

Habitat.—Fossil in Barbados.

Genus 513. Peripyramis,^[18] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archiphormida (vel Monocyrtida multiradiata aperta) with double, slenderly pyramidal shell, and numerous radial beams (six to nine or more). Network double, with an external arachnoidal or spongy envelope around the primary lattice-shell.

The genus Peripyramis differs from its probable ancestral form, Bathropyramis, by development of a delicate external envelope around the primary shell, and therefore bears to it the same relation that Spongopyramis among the Dicyrtida does to Sethopyramis. It may also be derived directly from the former by loss of the cephalis.

1. Peripyramis circumtexta, n. sp. (Pl. 54, fig. 5).

Shell slender, pyramidal, with nine strong radial beams, connected by fifteen to twenty transverse horizontal rings, which are partly complete, partly interrupted. Meshes subregular, square. From the nodal points of the surface there arise branched spines, which at equal distances from it are connected by thin threads, forming a delicate outer arachnoidal shell with large irregular polygonal meshes.

Dimensions.—Shell 0.32 long, 0.16 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Peripyramis spongiosa, n. sp.

Shell slender, pyramidal, with nine strong radial beams, connected by twelve to eighteen irregular interrupted rings. Meshes irregular, square or polygonal. From the whole surface arise numerous branched spines, which by communication and dense ramification form an outer spongy envelope around the shell. (Similar to Spongopyramis spongiosa, Pl. 56, fig. 10.)

Dimensions.—Shell 0.45 long, 0.32 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 514. Litharachnium,^[19] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 835.

Definition.—Archiphormida (vel Monocyrtida multiradiata aperta) with flatly conical, tent-shaped or nearly discoidal shell, and numerous, simple, radial beams in its wall.

The genus Litharachnium, and the closely allied genus Cladarachnium, differ from the preceding similar genera mainly in the flat form of the depressed shell, which is not slenderly pyramidal, but more tent-shaped or nearly discoidal. The radial ribs are generally not straight, but more or less curved. The top of the tent exhibits three or four important meshes, the original pores of the cortinar septum. Litharachnium may be derived directly from Sethophormis by reduction and loss of the cephalis.

Subgenus 1. Litharachnidium, Haeckel.

Definition.—Apex with three cortinar pores (one odd sternal and two paired cardinal pores).

1. Litharachnium tentorium, Haeckel.

Litharachnium tentorium, Haeckel, 1862, Monogr. d. Radiol., p. 281, Taf. iv. figs. 7-10.

Shell flatly conical or tent-shaped, with concave lateral outlines. Apex with three equal cortinar pores. Twenty radial ribs at nearly equal distances. Between them very numerous and thin secondary ribs, crossed by more than one hundred concentric rings. Pores square, as in all the following species. Margin truncate, circular.

Dimensions.—Shell 0.35 long, 0.8 broad.

Habitat.—Mediterranean (Messina).

2. Litharachnium araneosum (Pl. 55, figs. 8, 10).

Shell flatly conical, nearly discoidal, with straight lateral outlines. Apex with three unequal cortinar pores (one odd smaller sternal and two paired larger cardinal pores). Twenty radial ribs at unequal distances, with numerous intercalated secondary ribs. Margin ciliate.

Dimensions.—Shell 0.18 long, 0.32 broad.

Habitat.—Central Pacific, Station 271, surface.

3. Litharachnium arachnodiscus, Haeckel.

Litharachnium arachnodiscus, Haeckel, 1862, Monogr. d. Radiol., p. 283. Carpocanium arachnodiscus, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 296; Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, Taf. ii. fig. 8.

Shell flatly campanulate, nearly discoidal, with convex (?) lateral outlines. Apex with three unequal cortinal pores. Nine stronger radial primary ribs complete; between them numerous secondary intercalated ribs (sixty to seventy). Margin ciliate.

Dimensions.—Shell 0.03 long, 0.1 broad (?).

Habitat.—Arctic Ocean (between Greenland and Iceland), depth 1000 fathoms (Schaffner).

4. Litharachnium epeira, n. sp. (Pl. 55, fig. 9).

Shell flatly conical or tent-shaped, with concave lateral outlines. Apex with three unequal cortinar pores. Twelve stronger radial primary ribs complete; between them numerous (twenty-four to thirty-six) thinner secondary, and very numerous (more than one hundred) tertiary ribs. Margin reflexed, like the curved brim of a hat.

Dimensions.—Shell 0.12 long, 0.27 broad.

Habitat.—Central Pacific, Station 274, surface.

Subgenus 2. Litharachnoma, Haeckel.

Definition.—Apex with four cortinar pores (two anterior jugular and two posterior cardinal pores).

5. Litharachnium discoides, n. sp.

Shell flat, funnel-shaped, nearly discoidal, with concave outlines. Apex with four unequal cortinar pores (two smaller jugular and two larger cardinal pores). Twelve strong primary or perradial ribs alternating with twelve weaker secondary or interradial ribs; between these there are twenty-four shorter tertiary or adradial ribs, and in the outer flat, discoidal, half of the shell very numerous peripheral radial ribs (more than two hundred to three hundred). Margin flat, discoidal.

Dimensions.—Shell about 0.2 long, 1.12 broad.

Habitat.—Equatorial Atlantic, Station 347, surface.

6. Litharachnium pilidium, n. sp.

Shell flat, hat-shaped, with S-shaped outlines, in the upper half convex, in the lower half concave. Apex with four equal crossed cortinar pores. Thirty primary ribs of equal size; four of them are the prolongations of the four cortinar beams, eight intercalate between these secondary, and the other eighteen tertiary. Between them very numerous peripheral beams. Margin broad horizontal, reflexed like the brim of a "Bismarck" hat.

Dimensions.—Shell 0.17 long, 0.38 broad.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

Genus 515. Cladarachnium,^[20] Haeckel, 1881, Prodromus, p. 430.

Definition.—Archiphormida (vel Monocyrtida multiradiata aperta) with flatly conical, tent-shaped or nearly discoidal shell, and numerous branched radial beams.

The genus Cladarachnium differs from the preceding Litharachnium only in the ramification of the radial beams, the distal ends of which project over the margin of the shell. Only one species of the genus has been observed.

1. Cladarachnium ramosum, n. sp. (Pl. 55, figs. 5, 6).

Shell flatly conical or tent-shaped, with nearly straight lateral outlines; apical part somewhat higher. Apex with three cortinar pores surrounded by a few girdles of larger pores. From these there arise about twelve to fifteen strong radial beams at unequal distances; these are somewhat curved and irregularly branched. The network between them has irregular polygonal meshes and is more delicate towards the periphery. Margin with twenty-four to thirty irregular indentations or concave excisions, separated by the prominent distal ends of the branched ribs.

Dimensions.—Shell 0.16 long, 0.4 broad.

Habitat.—Central Pacific, Station 271, surface.

Genus 516. Cystophormis,^[21] n. gen.

Definition.—Archiphormida (vel Monocyrtida multiradiata aperta) with ovate or urceolate shell and numerous radial ribs in its wall. Mouth more or less constricted, smooth, truncated. Apex without horn.

The genus Cystophormis, like the preceding genera, exhibits numerous prominent radial or longitudinal ribs in the wall of the urceolate shell; it differs from these in the constricted and truncated mouth, with smooth margin of the peristome.

1. Cystophormis pila, n. sp. (Pl. 52, fig. 1).

Shell balloon-shaped, subspherical, with twenty denticulate meridional ribs, alternating with twenty longitudinal rows of circular pores, which are twice as broad as the bars. Peristome constricted and then dilated, smooth, half as broad as the shell.

Dimensions.—Shell 0.11 long, 0.09 broad; mouth 0.06 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Cystophormis ærostatica, n. sp. (Pl. 52, figs. 2, 3).

Shell balloon-shaped, subspherical, with twenty smooth meridional ribs, alternating with twenty longitudinal rows of circular pores, of the same breadth as the bars. Peristome constricted, about half as broad as the shell.

Dimensions.—Shell 0.09 long, 0.07 broad; mouth 0.03 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

3. Cystophormis spiralis, n. sp. (Pl. 51, fig. 9).

Shell ovate, one and a half times as long as broad, with twenty spirally convoluted, elegantly denticulated ribs, alternating with twenty spiral rows of small circular pores, of about the same breadth as the bars. Peristome constricted, very small, only one-seventh as broad as the shell.

Dimensions.—Shell 0.1 long, 0.07 broad; mouth 0.01 broad.

Habitat.—West Tropical Pacific, Station 225, depth 4475 fathoms.

4. Cystophormis tabulata (Pl. 79, fig. 2).

Shell urceolate and tabulate, twice as long as broad with twenty-five to thirty denticulated longitudinal ribs crossed by twenty to twenty-four transverse rings. Pores therefore regularly disposed in longitudinal and transverse rows; each pore circular, with a square frame. Peristome constricted, scarcely half as broad as the shell.

Dimensions.—Shell 0.2 long, 0.1 broad; mouth 0.04 broad.

Habitat.—South Pacific, Station 300, depth 1375 fathoms

Genus 517. Haliphormis,^[22] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54 (sensu mutato).

Definition.—Archiphormida (vel Monocyrtida multiradiata aperta) with numerous radial ribs in the wall of the campanulate shell, prolonged into free terminal feet. Apex with a horn.

The genus Haliphormis (with an apical horn) and the following Archiphormis (without a horn) comprise those Archiphormida in which the open mouth is more or less constricted and surrounded by a coronet of radial feet, as terminal prolongations of the radial ribs of its wall. The few forms, upon which Ehrenberg originally founded the genus Haliphormis, are partly not recognisable, partly belong to other genera. We therefore give here a new definition of the genus, as stated in my Prodromus, 1881, p. 428.

1. Haliphormis lagena, n. sp. (Pl. 97, fig. 5)

Shell bottle-shaped, twice as long as broad, tapering towards both ends, with nine longitudinal curved ribs. These are connected by irregular transverse beams, and the quadrangular meshes, so produced, are filled up by irregular, delicate, arachnoidal framework. The constricted mouth is half as broad as the middle part of the shell and surrounded by nine slender convergent feet, the free distal ends of the ribs. The apex bears a small knob with an oblique horn, perhaps the rudimentary cephalis of Sethamphora or Sethopyramis (?).

Dimensions.—Shell 0.6 to 0.7 long, 0.3 to 0.4 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

2. Haliphormis costata, n. sp.

Shell campanulate, somewhat longer than broad, with twelve prominent longitudinal ribs, alternating with twelve rows of regular circular pores. Mouth constricted half as broad as the shell, with twelve long triangular feet, formed by the free distal ends of the ribs. Apical horn short and stout, triangular pyramidal.

Dimensions.—Shell 0.12 long, 0.1 broad; mouth 0.07 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 518. Archiphormis,^[23] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archiphormida (vel Monocyrtida multiradiata aperta) with numerous radial ribs in the wall of the campanulate or urceolate shell, prolonged into free terminal feet. Apex without horn.

The genus Archiphormis differs from the preceding Haliphormis, its probable ancestral form, in the absence of the apical horn. The number of the longitudinal ribs, which are prolonged into terminal feet, is from six to nine or twelve or even more.

1. Archiphormis cancellata, Haeckel.

(?) Halicalyptra cancellata, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 243.

Shell cup-shaped or campanulate, with six prominent ribs, prolonged into six terminal triangular feet, one-third as long as the shell. Ribs connected by five or six transverse horizontal rings; meshes between them rounded squarish. (As Ehrenberg has given no figure of this species, its identity with the Challenger specimen is doubtful.)

Dimensions.—Shell 0.08 long, 0.06 broad; mouth 0.04 broad.

Habitat.—North Atlantic, Station 353, depth 2965 fathoms.

2. Archiphormis campanulata, n. sp.

Shell campanulate, with nine prominent denticulate ribs, prolonged into nine terminal feet, which are broad, lamellar, truncate, nearly vertical, one-third as long as the shell. Pores between the ribs circular, disposed in nine longitudinal and seven to eight transverse rows.

Dimensions.—Shell 0.09 long, 0.1 broad; mouth 0.06 broad.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

3. Archiphormis urceolata, n. sp. (Pl. 98, fig. 11).

Shell urceolate, with nine smooth prominent curved ribs, prolonged into nine triangular convergent short feet, scarcely one-sixth as long as the shell. Pores between the ribs in nine regular longitudinal rows, twice or three times as broad as long, quadrangular, eight to twelve pores in each row. Mouth constricted, half as broad as the shell.

Dimensions.—Shell 0.13 long, 0.11 broad; mouth 0.06 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 519. Halicalyptra,^[24] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54 (sensu emendato).

Definition.—Archiphormida (vel Monocyrtida multiradiata aperta) without radial ribs in the wall of the campanulate or ovate shell. Mouth with a coronet of radial feet. Apex with a horn.

The genus Halicalyptra and the two following closely allied genera differ from the preceding Archiphormida in the absence of radial ribs. The multiradiate structure is indicated only by the terminal spines or feet, forming a coronet around the mouth. These feet are either the free ends of reduced ribs, or new productions of the peristome. Halicalyptra may be derived from Calpophæna and Petalospyris by loss of the basal lattice-plate of the cephalis. But it is also possible that it has been derived from Anthocyrtis by loss of the cephalis, and that its shell corresponds to the thorax of the latter.

Subgenus 1. Acrocalpis, Haeckel, 1881, Prodromus, p. 427.

Definition.—Shell smooth, without spines or thorns (other than the feet and the apical horn).

1. Halicalyptra virginica, Ehrenberg.

Halicalyptra virginica, Ehrenberg, 1854, Mikrogeol., Taf. xviii. fig. 110.

Halicalyptra virginica, Haeckel, 1862, Monogr. d. Radiol., p. 289.

Haliomma virginicum, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 71.

Acrocalpis virginica, Haeckel, 1881, Prodromus, p. 427.

Shell smooth, campanulate, nearly hemispherical. Pores subregular circular, about as broad as the bars. Horn conical, half as long as the shell. Peristome scarcely constricted, with six conical divergent feet, as long as the horn.

Dimensions.—Shell diameter 0.04 to 0.05, length of the feet 0.02.

Habitat.—Fossil in tertiary rocks of Barbados and North America (Richmond, Virginia).

2. Halicalyptra campanula, n. sp.

Podocyrtis spinosa, Bury, 1862, Polycystins of Barbados, pl. xvii. fig. 3.

Shell smooth, campanulate. Pores irregular, roundish, about as broad as the bars. Horn large conical, about as long as the shell. Peristome not constricted, with six large divergent feet, which are as long as the shell, lamellar, with dentate edges.

Dimensions.—Shell diameter 0.07, length of the feet 0.07.

Habitat.—Fossil in Barbados.

3. Halicalyptra ampulla, n. sp.

Petalospyris foveolata, var., Bury, 1862, Polycystins of Barbados, pl. ix. fig. 1.

Shell smooth, subspherical, inflate. Pores regular, circular, twice as broad as the bars. Horn slender conical, about as long as the shell. Peristome constricted, with six divergent cylindrical, irregularly curved feet, twice to three times as long as the shell.

Dimensions.—Shell diameter 0.12, feet 0.2 to 0.3 long.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms; also fossil in Barbados.

4. Halicalyptra novena, n. sp.

Shell smooth, campanulate. Pores irregular, roundish. Horn slender conical, about as long as the shell. Peristome slightly constricted, with nine slender divergent feet of the same length. (Very similar to Petalospyris foveolata, Ehrenberg, but without internal columella and ring, with perfectly simple shell-cavity and open mouth.)

Dimensions.—Shell 0.09 diameter, feet 0.1 long.

Habitat.—Fossil in Barbados.

5. Halicalyptra petalospyris, n. sp. (Pl. 98, fig. 12).

Shell smooth, campanulate. Pores small, circular, irregularly scattered. Horn stout, pyramidal, about as long as the shell. Peristome scarcely constricted, with fifteen to twenty broad lamellar or lanceolate feet, which are twice to three times as long as the shell, parallel and vertical. (Very similar to Petalospyris flabellum, &c., Ehrenberg, 1875, loc. cit., Taf. xxii. figs. 6-8, but without any trace of sagittal ring or columella.)

Dimensions.—Shell 0.05 to 0.08 diameter, feet 0.15 to 0.25 long.

Habitat.—Central Pacific, Stations 266 to 268, depth 2700 to 2900 fathoms.

Subgenus 2. Echinocalpis, Haeckel, 1881, Prodromus, p. 427.

Definition.—Shell spiny, covered with numerous spines or thorns (besides the feet and the apical horn).

6. Halicalyptra spinosa, n. sp.

Shell spiny, ovate, inflate in the apical half. Pores irregular polygonal, four to eight times as broad as the bars. Peristome constricted, half as broad as the shell, with nine slender divergent feet, which like the apical horn are curved, twice to three times as long as the shell and five to ten times as long as the numerous bristles of the surface.

Dimensions.—Shell 0.08 long, 0.06 broad; feet 0.15 to 0.25 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

7. Halicalyptra castanella, n. sp.

Shell spiny, nearly spherical. Pores irregular roundish. Peristome constricted, scarcely one-third as broad as the shell, with twelve to twenty slender, widely divergent feet, which like the horn are irregularly curved, and longer than the shell. (Very similar to certain forms of the Phæodarium Castanella, Pl. 113, fig. 2.)

Dimensions.—Shell 0.13 diameter, feet 0.15 to 0.18 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Genus 520. Carpocanistrum,^[25] n. gen.

Definition.—Archiphormida (vel Monocyrtida multiradiata aperta) without radial ribs in the wall of the campanulate or ovate shell. Mouth with a corona of radial feet. Apex without horn.

The genus Carpocanistrum differs from the similar preceding Halicalyptra in the loss of the apical horn. It is very nearly related to the Dicyrtid Carpocanium and may be easily confounded with it. But in the latter the uppermost part of the shell-cavity includes a rudimentary cephalis with a cortinar septum, whilst in Carpocanistrum the cephalis is entirely lost, and the inner cavity quite simple. The number of the feet of the peristome is from nine to twenty, sometimes more. The mouth is commonly more or less constricted.

1. Carpocanistrum novenum, n. sp.

Shell ovate, smooth, one and a third times as long as broad. Pores regular circular, hexagonally framed, three times as broad as the bars, eight to ten on the greatest breadth of the shell. Peristome strongly constricted, one-third as broad as the shell, with nine large ovate lamellar, slightly convergent feet.

Dimensions.—Shell 0.08 long, 0.06 broad; mouth 0.02 broad.

Habitat.—South Atlantic, Station 325, surface.

2. Carpocanistrum flosculum, n. sp. (Pl. 52, fig. 9).

Shell campanulate, rough, thick-walled, of equal breadth and length. Pores regular circular, of the same breadth as the bars, twelve to fifteen on the greatest breadth of the shell. Peristome slightly constricted, with twelve elegant lanceolate, nearly vertical, a little convergent feet.

Dimensions.—Shell 0.07 long, 0.07 broad; mouth 0.05 broad.

Habitat.—Equatorial Atlantic, Station 347, surface.

3. Carpocanistrum giganteum, n. sp.

Shell ovate, smooth, very thick-walled, one and a third times as long as broad. Pores very numerous and small, subregular circular, forty to fifty on the greatest breadth of the shell, of about the same breadth as the bars. Peristome small, constricted, scarcely one-fourth as broad as the shell, with twelve to fifteen short triangular vertical feet.

Dimensions.—Shell 0.28 to 0.31 long, 0.21 to 0.23 broad; mouth 0.06 to 0.07 broad.

Habitat.—Fossil in Barbados.

4. Carpocanistrum acephalum, n. sp. (Pl. 52, fig. 10).

Shell ovate, smooth, thin-walled, one and a fifth times as long as broad. Pores subregular circular, twice as broad as the bars, sixteen to twenty on the greatest breadth of the shell. Peristome slightly constricted, with fifteen to eighteen slender, slightly bent, nearly vertical, and parallel feet, which are half as long as the shell.

Dimensions.—Shell 0.12 long, 0.1 broad; mouth 0.07 broad.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

5. Carpocanistrum evacuatum, n. sp. (Pl. 52, fig. 11).

Shell urceolate, smooth, thin-walled, one and a half times as long as broad. Pores regular circular, sixteen to twenty on the greatest breadth of the shell. Peristome slightly constricted, with twenty to twenty-five small triangular vertical feet.

Dimensions.—Shell 0.1 long, 0.07 broad; mouth 0.05 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

6. Carpocanistrum pyriforme, Haeckel.

Lithocarpium pyriforme, Stöhr, 1880, Palæontogr., vol. xxvi. p. 97, Taf. iii. fig. 10.

Shell pear-shaped or subspherical, one and a fourth times as long as broad. Pores roundish, polygonally framed (or with square meshes ?). Peristome strongly constricted, one-fourth as broad as the shell, somewhat tubular, with twelve to twenty short vertical and parallel feet. The position of this species is doubtful; perhaps it represents a peculiar genus.

Dimensions.—Shell 0.17 long, 0.14 broad; mouth 0.035 broad.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte) Stöhr.

Genus 521. Arachnocalpis,^[26] Haeckel, 1881, Prodromus, p. 427.

Definition.—Archiphormida (vel Monocyrtida multiradiata aperta) with an ellipsoidal or nearly spherical double shell; outer shell arachnoidal or spongy. Peristome small, constricted with a corona of numerous radial feet. No apical horn.

The genus Arachnocalpis differs from the other Archiphormida by possessing a double shell (like Peripyramis). The large shell, reaching nearly half a millimeter in length is either ellipsoidal or nearly spherical, and composed of an inner primary and an outer secondary shell. Its network is very delicate, in the outer envelope either spongy or arachnoidal. This very remarkable genus has probably no true relation to the other Archiphormida but has been derived from true Calpoidea (Mitrocalpis) by development of a corona around the mouth.

1. Arachnocalpis ellipsoides, n. sp. (Pl. 98, fig. 13).

Shell ellipsoidal, one and a half times as long as broad, on the apical pole hemispherical, on the basal pole coronate, with an elegant prominent funnel-shaped peristome, which is one-eighth as broad as the shell, fenestrated by very fine pores, and bears fifteen to twenty short conical divergent teeth. Inner shell with irregular polygonal meshes of very different size, separated by thin, finely-denticulate bars. Outer spongy shell very delicate, arachnoidal, with numerous prominent conical spongy papillæ. Central capsule ellipsoidal, half as long and broad as the shell.

Dimensions.—Shell 0.46 long, 0.32 broad; mouth 0.045 broad.

Habitat.—Central Pacific, Stations 271 to 274, surface.

2. Arachnocalpis sphæroides, n. sp.

Shell spheroidal, of the same structure as the preceding ellipsoidal species, with the same form of the spongy envelope; differing from it in the globose form and the shorter peristome, bearing only nine or ten small conical divergent teeth. Central capsule spherical.

Dimensions.—Shell 0.3 diameter, mouth 0.04 broad.

Habitat.—Central Pacific, Stations 265 to 270, surface.

Subfamily 2. Archiphænida, Haeckel, 1881, Prodromus, p. 429.

Definition.—Phænocalpida with the basal mouth of the shell fenestrated (vel Monocyrtida multiradiata clausa).

Genus 522. Phænocalpis,^[27] n. gen.

Definition.—Archiperida (vel Monocyrtida multiradiata clausa) with an internal axial simple columella, prolonged outside into an apical horn.

The genus Phænocalpis and the following Phænoscenium comprise those Archiphænida in which the vertical axis of the shell-cavity is occupied by a simple or branched columella, arising from the centre of the base and prolonged into an apical horn. This columella may be either the vertical rod of a Plectaniscus or the remnant of an original ring of Petalospyris. The latter genus differs by its sagittal constriction.

1. Phænocalpis petalospyris, n. sp. (Pl. 97, fig. 4).

Shell subspherical, rough, with irregular, roundish pores, larger than the bars. Columella straight, central, thin, prolonged into a large apical horn with three dentate edges. Six basal feet curved, divergent, lamellar, with a middle rib and dentate edges.

Dimensions.—Shell 0.07 long, 0.05 broad; horn and feet 0.06 long.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

2. Phænocalpis ocellata, Haeckel.

Petalospyris ocellata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xxii. fig. 9.

Shell subspherical, smooth, with irregular roundish pores, about as broad as the bars. Columella slightly curved and excentric, prolonged into a slender conical horn of the same length. Six basal feet similar to the horn, slightly divergent.

Dimensions.—Shell 0.06 long, 0.07 broad; horn and feet 0.05 long.

Habitat.—Fossil in Barbados.

3. Phænocalpis carinata, Haeckel.

Petalospyris carinata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xxii. fig. 6.

Shell campanulate, rough, with irregular roundish pores, smaller than the bars. Columella straight, central, prolonged into a stout conical horn of the same length. Nine basal feet slender, triangular, longer than the shell, nearly vertical, with a middle rib in the basal half.

Dimensions.—Shell 0.05 long, 0.06 broad; horn 0.04 long, feet 0.08 long.

Habitat.—Fossil in Barbados.

4. Phænocalpis flabellum, Haeckel.

Petalospyris flabellum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xxii. fig. 7.

Shell campanulate smooth, with very small circular pores, half as broad as the bars. Columella straight, central, prolonged into a pyramidal horn of half the length. Twelve to fifteen basal feet lamellar, linear, twice to three times as long as the shell, parallel and vertical, pointed at the distal end.

Dimensions.—Shell 0.04 long, 0.05 broad; horn 0.02 long, feet 0.1 to 0.12 long.

Habitat.—Fossil in Barbados.

Genus 523. Phænoscenium,^[28] n. gen.

Definition.—Archiphænida (vel Monocyrtida multiradiata clausa) with an internal axial branched columella, prolonged outside into an apical horn.

The genus Phænoscenium differs from the preceding Phænocalpis in the branched columella, which is connected by three or six ascending branches with the inner wall of the shell. It bears therefore to the latter the same relation that Cladoscenium exhibits to Euscenium. The former genera may have been derived from the latter by interpolation of new interradial feet between the three primary perradial feet.

1. Phænoscenium hexapodium, n. sp. (Pl. 98, fig. 9).

Shell campanulate, smooth, about as long as broad. Network delicate, with irregular polygonal pores and thin bars. Columella with four to six ascending three-branched verticils, prolonged into the conical hollow apical horn (with six to eight smaller verticils) which is about as long as the shell. Six basal feet curved, divergent, of the same length, with pinnate middle rod.

Dimensions.—Shell 0.1 long, 0.11 broad; horn and feet 0.08 to 0.09 long.

Habitat.—Central Pacific, Section 271, depth 2425 fathoms.

2. Phænoscenium cladopodium, n. sp.

Shell campanulate, conical, smooth, somewhat broader than long. Network with irregular roundish pores, about as broad as the bars. Columella with a single verticil of three ascending branches. Horn pyramidal, stout, as long as the shell, with three dentate edges. Six feet divergent, slightly curved, very unequal; three primary (or perradial) very large, longer than the shell, three sided pyramidal, with three dentate edges; three secondary (or interradial) much smaller, simple, shorter than the shell.

Dimensions.—Shell 0.05 long, 0.06 broad; horn and feet 0.04 to 0.07 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Phænoscenium polypodium, n. sp.

Shell subspherical, about as long as broad, smooth. Network with regular circular pores, twice as broad as the bars. Columella with two verticils of three ascending branches, prolonged into a stout conical horn of twice the length. Twelve to fifteen conical curved divergent feet, about as long as the shell. The three primary feet are directly connected with the base of the columella.

Dimensions.—Shell 0.08 diameter, horn 0.15 long, feet 0.07 to 0.09 long.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 524. Calpophæna,^[29] Haeckel, 1881, Prodromus, p. 429.

Definition.—Archiphænida (vel Monocyrtida multiradiata clausa) with an apical horn and simple internal cavity of the shell without axial columella.

The genus Calpophæna and the following closely tied Archiphæna differ from the two preceding genera of Archiphænida in the simple shell cavity, which encloses no columella. They may be derived either from the preceding Phænocalpis by loss of the columella, or directly from the Zygospyrida by reduction of the sagittal constriction and loss of the primary ring. Different subgenera may be distinguished in Calpophæna according either to the number of the feet or to their shape (being simple or branched).

Subgenus 1. Acrocorona, Haeckel, 1881, Prodromus, p. 430.

Definition.—Feet simple, not branched nor forked.

1. Calpophæna tetrarrhabda, n. sp.

Shell subspherical, tuberculate, with subregular circular pores. Apical horn conical, about as long as the shell. Basal plate with a regular cross of four equal cortinar pores, separated by four bars; these are crossed in the sagittal and frontal diameter, and prolonged into four equal conical divergent feet, about as long as the shell.

Dimensions.—Shell 0.1 diameter, horn and feet 0.1 to 0.12 long.

Habitat.—South Pacific, Station 297, depth 1775 fathoms.

2. Calpophæna hexarrhabda, n. sp. (Pl. 53, figs. 17, 18).

Shell subspherical, rough, with irregular roundish pores. Apical horn conical, shorter than the shell. Basal plate (fig. 18) with three pairs of triangular pores, two larger (cardinal) pores in the middle, two smaller (cervical) at the dorsal, and two intermediate (jugular) at the ventral side. The bars between them are prolonged into six equal cylindrical divergent feet, nearly as long as the shell, provided with a spiny knob at the end.

Dimensions.—Shell 0.09 long, 0.08 broad; horn and feet 0.06 to 0.08 long.

Habitat.—Tropical Pacific, Station 224, depth 1850 fathoms.

3. Calpophæna ennearrhabda, n. sp.

Shell subspherical, spiny, with irregular, roundish pores. Apical horn cylindrical, longer than the shell. Basal plate with nine collar pores, three larger central alternating with three pairs of smaller peripheral (like Pl. 87, fig. 2). Corona with nine slender cylindrical, slightly curved, divergent feet, somewhat longer than the shell.

Dimensions.—Shell 0.11 long, 0.1 broad; horn and feet 0.12 to 0.15 long.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

4. Calpophæna enneaphylla, n. sp.

Shell ovate, smooth, with regular circular pores. Apical horn pyramidal, half as long as the shell. (Basal plate with four cortinar pores?) Corona with nine broad, lamellar, truncate, vertical feet, about as long as the horn.

Dimensions.—Shell 0.12 long, 0.09 broad; horn and feet 0.06 long.

Habitat.—Central Pacific, Station 271, surface.

5. Calpophæna petalospyris, n. sp.

Shell campanulate, tuberculate, with irregular, roundish pores. Apical horn conical, shorter than the shell. (Basal plate with nine pores?) Corona with twelve to twenty broad, lamellar, truncate, vertical feet, of different sizes, somewhat irregular.

Dimensions.—Shell 0.08 long, 0.09 broad; horn and feet 0.07 to 0.12 long.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 2. Cladocorona, Haeckel, 1881, Prodromus, p. 430.

Definition.—Feet branched or forked.

6. Calpophæna tetracorethra, n. sp.

Shell subspherical, smooth, with irregular, roundish pores. Basal plate with four larger pores. Apical horn and the four divergent basal feet of equal size and similar form, three to four times as long as the shell, slender, bristle-shaped, curved, in the distal half irregularly branched. (Very similar to the remarkable Tetraspyris tetracorethra, Pl. 53, figs. 19, 20, but with shorter appendages and with simple spherical shell, which exhibits no trace of sagittal ring and constriction.)

Dimensions.—Shell 0.12 diameter, horn and feet 0.3 to 0.5 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

7. Calpophæna hexacorethra, n. sp.

Shell subspherical, smooth, similar to the preceding species. Basal plate with six pores. Apical horn and the six divergent feet twice to three times as long as the shell, bristle-shaped, irregularly curved and branched. (Similar to Hexaspyris hexacorethra, Pl. 95, fig. 8, but without sagittal ring and constriction.)

Dimensions.—Shell 0.11 long, 0.13 broad; horn and feet 0.2 to 0.3 long.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 525. Archiphæna,^[30] Haeckel, 1881, Prodromus, p. 429.

Definition.—Archiphænida (vel Monocyrtida multiradiata clausa), with simple internal cavity of the shell, without apical horn and axial columella.

The genus Archiphæna has the same simple cavity of the shell as the preceding Calpophæna, but differs from it in the loss of the apical horn. It bears therefore to the latter the same relation that Gorgospyris does to Petalospyris. The two former genera may be derived from the two latter by loss of the sagittal ring and constriction.

Subgenus 1. Coronophæna, Haeckel, 1881, Prodromus, p. 429.

Definition.—Feet simple, not branched nor forked.

1. Archiphæna gorgospyris, n. sp. (Pl. 98, figs. 10, 10a).

Shell hemispherical, smooth, with small subregular, circular pores. Collar septum with four large pores (fig. 10a). Twelve to fifteen feet, divergent, lamellar, truncate, about as long as the shell. (Similar to certain forms of Gorgospyris, Pl. 87, figs. 1 to 3, but with simple shell cavity, without sagittal ring and constriction, and without a columella.)

Dimensions.—Shell 0.08 long, 0.04 broad; feet 0.03 to 0.04 long.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

2. Archiphæna corona, n. sp.

Shell crown-shaped, somewhat broader than long, at the base flattened, papillate, with irregular roundish pores. Twenty to twenty-five feet, broad, lamellar, truncate, nearly vertical, about twice as long as the shell.

Dimensions.—Shell 0.1 long, 0.12 broad; feet 0.2 to 0.22 long.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Subgenus 2. Stephanophæna, Haeckel, 1881, Prodromus, p. 429.

Definition.—Feet branched or forked.

3. Archiphæna stephanoma, n. sp.

Shell campanulate, somewhat longer than broad, with subregular, circular pores. Margin of the flattened base with a corona of about twenty unequal feet, which are partly simple, partly irregularly branched, and about as long as the shell.

Dimensions.—Shell 0.11 long, 0.03 broad; feet 0.08 to 0.12 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Family LXI. Cyrtocalpida, n. fam.

Archicorida et Archicapsida, Haeckel, 1881, Prodromus, pp. 427, 428.

Definition.—Monocyrtida eradiata. (Cyrtoidea with a simple, not jointed shell, representing a simple cephalis without radial apophyses.)

The family Cyrtocalpida, composed of the Archicorida and Archicapsida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is quite simple, without transverse constriction, and without radial apophyses. The two subfamilies differ in the shape of the basal mouth, which in the Archicorida is a simple wide opening, but in the Archicapsida is closed by a lattice-plate.

Only a few species of this family were formerly known. Ehrenberg, in 1838, founded upon these the genus Cornutella, one of the three oldest genera of Polycystina (Cornutella, Lithocampe, Haliomma). In 1862 I described some living forms, with a central capsule, as Cyrtocalpis. The Challenger collection contains a large number of new genera and species.

Probably the family Cyrtocalpida is an artificial group, comprising two or more different subfamilies of very different origin. The Cornutellida (Cornutella, Cornutanna) have probably been derived from the Sethocorida by loss of the cephalis, so that their conical shell represents a thorax alone. The Mitrocalpida on the other hand (genera 528-531) may be originally simple ovate shells (like Gromia and Lecythium), arising independently from the Nassellida. The Archicapsida (Halicapsa, Archicapsa) are probably derived from the Zygospyrida (Dictyospyris, Circospyris) by loss of the sagittal ring and constriction. This is nearly certain, when the three or four typical cortinar pores appear in their basal plate. Some forms of Halicapsa may be easily confounded with some forms of Prunoidea (Lithapium).

Those Cyrtocalpida, which possess a central capsule with three or four lobes, are probably derived from Tripocyrtida by loss of the three feet, or from Sethocyrtida by loss of the cephalis, since the lobes indicate the original presence of cortinar pores and of a cephalis. Those Cyrtocalpida, however, in which a simple ovate shell encloses a simple central capsule without lobes, may be original "Monocyrtida eradiata," without relation to any radial ancestral forms.

Synopsis of the Genera of Cyrtocalpida.

I. Subfamily Archicorida. Basal mouth of the shell a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell with simple lattice-work (not double or spongy).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell conical, gradually dilated towards the mouth.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	With horn,	526. Cornutella.
						No horn,	527. Cornutanna.
				Shell ovate or urceolate, with constricted mouth.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	With horn,	528. Archicorys.
						No horn,	529. Cyrtocalpis
		Shell not simply latticed.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Shell ovate, double, with an external mantle,			530. Mitrocalpis.
				Shell ovate, with spongy irregular, lattice-work			531. Spongocyrtis.
II. Subfamily Archicapsida. Mouth closed by a lattice plate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Shell with an apical horn,					532. Halicapsa.
		Shell without horn on the apex,					533. Archicapsa.

Subfamily 1. Archicorida, Haeckel, 1881, Prodromus, p. 427.

Definition.—Cyrtocalpida, with the basal mouth of the shell open (vel Monocyrtida eradiata aperta).

Genus 526. Cornutella,^[31] Ehrenberg, 1838, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 128.

Definition.—Archicorida with conical shell, gradually dilated towards the wide open mouth. Apex armed with a horn.

The genus Cornutella is one of the three oldest genera of Polycystina, described by Ehrenberg, in 1838 (Cornutella, Lithocampe, and Haliomma). He afterwards enumerated, in 1872 and 1875, a large number of fossil and living species, the majority of which, however, belong to other genera of Monocyrtida and Dicyrtida (at least six or seven different genera). We retain here as the true type of the genus the oldest known species:—Cornutella clathrata, and the nearly allied forms Cornutella stylophæna, Cornutella mitra, Cornutella circularis, &c. The simple conical shell exhibits no distinct trace of an original cephalis, excepting the apical horn; it may have originated either independently, or been derived from Sethoconus, by loss of the cephalis.

Subgenus 1. Cornutellium, Haeckel.

Definition.—Axis of the conical shell straight. Pores polygonal, or roundish with polygonal frames.

1. Cornutella hexagona, n. sp. (Pl. 54, fig. 9).

Shell slender, conical, with straight outlines. Pores subregular, hexagonal, gradually increasing in size towards the mouth; in about ten to twelve longitudinal series, in the upper part very small. Horn slenderly conical, nearly bristle-shaped, long.

Dimensions.—Shell 0.1 to 0.15 long, 0.04 to 0.06 broad.

Habitat.—Central Pacific, Stations 265 to 274, surface, and at different depths.

2. Cornutella sethoconus, n. sp. (Pl. 54, fig. 10).

Shell slender, conical, with undulate outlines. Pores subregular, hexagonal, gradually increasing in size towards the mouth, in about fifteen to eighteen longitudinal series, in the upper part circular. Horn small, conical, short. The network is not so delicate as in the preceding similar species.

Dimensions.—Shell 0.12 to 0.16 long, 0.06 to 0.08 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

3. Cornutella distenta, Ehrenberg.

Cornutella distenta, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. vi. III. fig. 3.

Shell slender, conical, with straight outlines. Pores small, circular, regularly disposed in six to eight alternating longitudinal rows, each pore surrounded by a large rhombic frame. The connected frames form together a regular rhombic framework with obliquely crossed crests. Horn conical, stout, large.

Dimensions.—Shell 0.1 to 0.15 long, 0.04 to 0.06 broad.

Habitat.—North Pacific, Californian Sea, depth 2600 fathoms, Ehrenberg.

4. Cornutella stiligera, Ehrenberg.

Cornutella stiligera, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 1; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 68, Taf. ii. fig. 3.

Shell slender, conical, with straight outlines. Pores subregular, rhombic or nearly square, disposed in oblique series, separated by parallel obliquely ascending rings, which are crossed by interrupted parallel bars. Horn slenderly conical or bristle-shaped, thin and long.

Dimensions.—Shell 0.08 to 0.12 long, 0.03 to 0.04 broad.

Habitat.—Fossil in Barbados.

Subgenus 2. Cornutissa, Haeckel, 1881, Prodromus, p. 427.

Definition.—Axis of the conical shell straight. Pores circular or roundish, without polygonal frames.

5. Cornutella circularis, Ehrenberg.

Cornutella circularis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 4.

Shell wide, conical or funnel-shaped, with straight outlines. Pores very large, circular, ten to twenty times as broad as the bars, in about nine to twelve longitudinal alternating rows, increasing gradually towards the mouth. Horn very large, cylindrical.

Dimensions.—Shell 0.1 to 0.15 long, 0.08 to 0.12 broad.

Habitat.—Fossil in Barbados.

6. Cornutella mitra, Ehrenberg.

Cornutella mitra, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 8.

Shell wide, conical, campanulate, with convex outlines. Pores subregular, circular, nearly equal in size, not regularly disposed in rows. Horn conical, stout.

Dimensions.—Shell 0.12 to 0.16 long, 0.08 to 0.12 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

7. Cornutella clathrata, Ehrenberg.

Cornutella clathrata, Ehrenberg, 1838, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 129; Mikrogeol., Taf. xxii. fig. 39. Cornutella clathrata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. ii. fig. 9.

Shell wide, conical with slightly convex outlines. Pores regular, circular, gradually increasing in size towards the mouth, disposed in twelve to fifteen longitudinal alternating rows. Horn short and stout, conical. (Compare Cornutella curvata.)

Dimensions.—Shell 0.15 to 0.2 long, 0.06 to 0.09 broad.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific; also fossil in tertiary rocks of Barbados, Nikobar and Sicily.

8. Cornutella stylophæna, Ehrenberg.

Cornutella stylophæna, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. vi. III. fig. 1. ? Cornutella tumens, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. vi. III. fig. 4.

Shell slender, conical, with undulate outlines. Pores subregular, circular, gradually increasing in size, disposed in six to nine quincuncial alternating longitudinal rows. Horn very long, cylindro-conical, sometimes about as long as the shell.

Dimensions.—Shell 0.1 to 0.13 long, 0.04 to 0.06 broad.

Habitat.—North Pacific, Californian Sea, depth 2600 fathoms.

9. Cornutella granulata, Ehrenberg.

Cornutella granulata, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. vi. III. fig. 5.

Shell slender, conical, nearly cylindrical, with straight outlines, rounded at the apex. Pores very small and numerous, punctiform, disposed into very numerous parallel transverse rows. Horn small, conical (may be perhaps the shell of a Tintinnoid Infusorium?).

Dimensions.—Shell 0.08 long, 0.02 broad.

Habitat.—North Pacific, Californian Sea, depth 2600 fathoms.

10. Cornutella annulata, Ehrenberg.

Cornutella annulata, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ii. fig. 16.

Shell slender, conical, nearly cylindrical, with straight outlines, rounded at the apex. Pores small and numerous, regular circular, of equal size, regularly disposed in ten to fifteen parallel transverse series. Horn bristle-shaped. (Compare Artostrobus annulatus, Cornutella annulata, Bailey.)

Dimensions.—Shell 0.1 to 0.13 long, 0.03 to 0.04 broad.

Habitat.—Cosmopolitan, Atlantic, Pacific, surface.

Subgenus 3. Cornutosa, Haeckel, 1881, Prodromus, p. 427.

Definition.—Axis of the conical shell curved. Pores circular or roundish.

11. Cornutella curvata, Haeckel.

Cornutella clathrata, var., Ehrenberg, 1854, Mikrogeol., Taf. xxii. figs. 39a, b, c. Cornutosa clathrata, Haeckel, 1881, Prodromus, p. 427.

Shell slender, conical, with curved axis; the curve lies in one plane and is not spirally convoluted. Pores subregular, circular, of nearly equal size, quincuncially disposed. Horn short, conical.

Dimensions.—Shell 0.1 to 0.15 long, 0.04 to 0.06 broad.

Habitat.—Fossil in tertiary rocks of Sicily (Caltanisetta).

12. Cornutella spiralis, n. sp.

Cornutura spiralis, Haeckel, 1881, Prodromus, p. 427.

Shell slender, conical, nearly cylindrical, very long, spirally contorted; its axis is an ascending spiral line with two or three windings, widely distant. Pores irregular, square, small and numerous.

Dimensions.—Shell 0.2 to 0.25 long, 0.05 to 0.08 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 527. Cornutanna,^[32] Haeckel, 1881, Prodromus, p. 427.

Definition.—Archicorida with conical shell, gradually dilated towards the wide open mouth. Apex without horn.

The genus Cornutanna has the same simple conical shell as the preceding Cornutella, but differs from it in the total absence of an apical horn. It bears therefore to the latter the same relation that Cyrtocalpis does to Archicorys. It may be derived from Sethoconus by complete reduction of the cephalis and its horn.

1. Cornutanna orthoconus, n. sp.

Shell slender, conical, with straight axis and straight outlines. Pores subregular, circular, quincuncially disposed in nine to twelve alternating longitudinal series, gradually increasing in size towards the mouth.

Dimensions.—Shell 0.1 to 0.12 long, 0.03 to 0.04 broad.

Habitat.—Central Pacific, Stations 270 to 274, surface.

2. Cornutanna cyrtoconus, n. sp.

Shell slender, conical, with curved axis; the curve lies in one plane as in the similar Cornutella curvata; the pores are smaller and more numerous than in this latter species, and the rounded apex bears no horn.

Dimensions.—Shell 0.12 to 0.16 long, 0.05 to 0.07 broad.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

3. Cornutanna loxoconus, n. sp.

Shell wide, conical, with irregularly curved axis; the parts of the curve do not lie in one plane. Pores very small and numerous, of nearly equal size.

Dimensions.—Shell 0.2 long, 0.12 broad.

Habitat.—Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 528. Archicorys,^[33] Haeckel, 1881, Prodromus, p. 427.

Definition.—Archicorida with simple urceolate or ovate shell, constricted towards the mouth. Apex armed with a horn.

The genus Archicorys and the following closely allied Cyrtocalpis differ from the two preceding genera in the ovate or urceolate form of the shell, which is more or less constricted towards the terminal mouth. The upper pole in Archicorys bears an apical horn, which is absent in Cyrtocalpis. The origin of these two genera may be the same, probably arising directly from Nassellida, and independently of the triradiate Cyrtoidea or bilocular Spyroidea. (Compare p. 1179.)

1. Archicorys galea, n. sp.

Shell smooth urceolate. Pores large, in the middle part hexagonal, towards both ends smaller and polygonal. Apical horn stout, three-sided pyramidal, half as long as the shell. Mouth with a short tubular peristome, about one-third as broad as the shell.

Dimensions.—Shell (without horn) 0.15 long, 0.12 broad; horn 0.07 long, mouth 0.05 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Archicorys ampulla, n. sp.

Shell smooth, thin-walled, bottle-shaped, in the upper half conical, in the lower half inflate, subspherical. Pores subregular, circular, of the same breadth as the bars. Horn conical, stout, about one-third as long as the shell. Mouth truncate, without peristome, about half as broad as the shell.

Dimensions.—Shell 0.15 long, 0.1 broad; horn 0.05, mouth 0.05.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Archicorys microstoma, n. sp. (Pl. 51, fig. 12).

Shell rough, thick-walled, ovate. Pores large, subregular, circular, twice to four times as broad as the bars. Horn small, conical, not larger than one pore. Mouth very small, truncate, scarcely larger than one pore.

Dimensions.—Shell 0.1 long, 0.07 broad; horn 0.012, mouth 0.015.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

4. Archicorys globosa, n. sp.

Shell nearly spherical, thorny, thick-walled. Pores very large, circular, separated by spinulate frames, smaller towards each pole. Horn conical, large, nearly as long as the radius of the shell; mouth truncate, simple, about one-third as broad as the shell.

Dimensions.—Shell diameter 0.13, horn 0.06, mouth 0.04.

Habitat.—Fossil in Barbados.

5. Archicorys ovata, n. sp. (Pl. 51, fig. 10).

Shell ovate, rough, thick-walled. Pores regular, circular, of equal size, very small and numerous, quincuncially disposed. Horn small, conical, sometimes (as in the figured specimen) rudimentary. When it becomes lost, the species may be called Cyrtocalpis ovata. Mouth truncate, small, simple, one-sixth as broad as the shell.

Dimensions.—Shell 0.2 long, 0.15 broad; horn 0.01 to 0.03 long, mouth 0.03 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 529. Cyrtocalpis,^[34] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 835.

Definition.—Archicorida with simple urceolate or ovate shell, constricted towards the mouth. Apex without horn.

The genus Cyrtocalpis comprises a large number of common, very primitive Monocyrtida, which in the simple ovate or urceolate form of the shell resemble the well known Gromia among the Thalamophora. Its basal mouth is more or less constricted, as in the preceding genus Archicorys, from which it differs in the total absence of an apical horn. There is no trace of any triradial structure, excepting in some smaller species, in which the basal part of the central capsule is trilobate; these may be derived from the Dicyrtides Sethocorys or Dictyocephalus, by loss of the cephalis and the cortinar septum. But the larger species, which have a quite simple, ovate, central capsule (Pl. 51, fig. 13), have probably an independent origin, from Cystidium.

1. Cyrtocalpis urceolus, n. sp. (Pl. 51, fig. 13).

Shell smooth, urceolate, with very delicate and elegant network. Pores in the middle part large, regular, hexagonal, towards each pole smaller, irregular, roundish or polygonal. Mouth with broad, hyaline, annular peristome, about one-third as broad as the shell.

Dimensions.—Shell 0.16 long, 0.12 broad; mouth 0.05 broad.

Habitat.—Mediterranean (Portofino near Genoa), surface.

2. Cyrtocalpis reticulum, n. sp.

Shell smooth, urceolate, very similar to the preceding species, but differing from it in the densely reticulated framework of the shell, which is composed of very numerous and small, irregular, polygonal meshes of nearly equal size. Mouth without peristome, half as broad as the shell.

Dimensions.—Shell 0.18 long, 0.15 broad; mouth 0.07 broad.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

3. Cyrtocalpis amphora, Haeckel.

Cyrtocalpis amphora, Haeckel, 1862, Monogr. d. Radiol., p. 286, Taf. v. fig. 2.

Shell smooth, urceolate with regular, circular pores of equal size, of about the same breadth as the bars. Mouth with smooth peristome, about half as broad as the shell.

Dimensions.—Shell 0.12 long, 0.08 broad; mouth 0.04 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific; surface, and at various depths.

4. Cyrtocalpis urna, Stöhr.

Cyrtocalpis urna, Stöhr, 1880, Palæontogr., vol. xxvi. p. 96, Taf. iii. fig. 7.

Shell smooth, urceolate, with subregular, circular pores of different sizes, gradually increasing towards the mouth, of about the same breadth as the bars. Mouth without peristome (?), about half as broad as the shell.

Dimensions.—Shell 0.09 long, 0.06 broad; mouth 0.035 broad.

Habitat.—Fossil in tertiary rocks of Sicily (Grotte).

5. Cyrtocalpis sethopora, n. sp. (Pl. 52, fig. 4).

Shell smooth, urceolate, very thin-walled, with large irregular roundish meshes, each of which is closed by a thin porous sieve-plate. Mouth two-thirds as broad as the shell, with a broad, emarginate, longitudinally striped peristome. (Perhaps the shell of a Tintinnoid Infusorium?)

Dimensions.—Shell 0.08 long, 0.05 broad; mouth 0.03 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

6. Cyrtocalpis compacta, n. sp. (Pl. 52, figs. 7, 8).

Shell smooth, ovate, very thick-walled, with small, subregular, circular pores of equal size, perpendicularly perforating the wall, about half as broad as the bars. Mouth small, only one-third as broad as the compact shell. (Perhaps a reduced Lithocampe or Lithomitra?)

Dimensions.—Shell 0.08 long, 0.04 broad; mouth 0.015 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

7. Cyrtocalpis lithomitra, n. sp. (Pl. 52, figs. 5, 6).

Shell smooth, slender, ovate, nearly cylindrical, with small subregular, circular pores, which are disposed in nine to twelve transverse rows, and obliquely ascending perforate the wall. Mouth wide, without peristome, about two-thirds as broad as the shell. (Compare Lithomitra, Pl. 79.)

Dimensions.—Shell 0.09 long, 0.045 broad; mouth 0.03 broad.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms; also fossil in Barbados.

8. Cyrtocalpis ovulum, n. sp.

Cyrtocalpis obliqua, var. ovulum, Haeckel, 1862, Monogr. d. Radiol., p. 286, Taf. v. fig. 3.

Shell smooth, broad, ovate, with very numerous and small regular circular pores, quincuncially disposed, twice as broad as the bars. Mouth without peristome, about half as broad as the shell.

Dimensions.—Shell 0.09 long, 0.047 broad; mouth 0.04 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

9. Cyrtocalpis obliqua, Haeckel.

Cyrtocalpis obliqua, Haeckel, 1862, Monogr. d. Radiol., p. 286, Taf. v. figs. 4-11.

Shell smooth, irregularly ovate, more or less oblique, variable in size and form, sometimes nearly spherical, at other times subcylindrical. Pores subregular, circular, once or twice the breadth of the bars. Mouth simple without peristome, about half as broad as the shell.

Dimensions.—Shell 0.07 to 0.1 long, 0.05 to 0.08 broad; mouth 0.03 to 0.04 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, surface.

10. Cyrtocalpis gromia, n. sp. (Pl. 51, fig. 11).

Shell rough, ovate, very thick-walled, with subregular, circular pores of somewhat variable size. The diameter of the internal, simple, subspherical cavity is five to six times as great as the thickness of the wall. Mouth tubular, cylindrical, very narrow, only one-sixth as broad as the shell.

Dimensions.—Shell 0.16 long, 0.11 broad; mouth 0.02 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 530. Mitrocalpis,^[35] Haeckel, 1881, Prodromus, p. 427.

Definition.—Archicorida with a double ovate or ellipsoidal shell, composed of two parallel lattice-plates, which are connected by numerous beams. Apex without horn.

The genus Mitrocalpis and the following closely allied Spongocyrtis differ from the four preceding genera of Archicorida in the complicated structure of the shell-wall, which in the former is double, in the latter spongy. The mouth is in both genera constricted, narrow, and the apex without a horn. Mitrocalpis has been derived probably from Cyrtocalpis in the same way as Peripyramis from Bathropyramis, by development of spines on the surface of the shell, which at equal distances from the latter become connected by branches, thus forming an outer envelope.

1. Mitrocalpis palliata, n. sp.

Shell ellipsoidal, large, one and a third times as long as broad. Inner shell very thin-walled, with irregular, polygonal pores of very variable size and form. From its nodal points there arise numerous bristle-shaped radial beams, about as long as the diameter of the mouth, which are connected at equal distances from the surface by delicate threads, forming the outer enveloping shell. The surface of the latter is smooth. The thin bars of the inner shell are twice to four times as broad as those of the outer. Mouth about one-seventh as broad as the shell, with a short tubular peristome.

Dimensions.—Shell 0.35 long, 0.27 broad; mouth 0.04, distance of both shells 0.037.

Habitat.—Central Pacific, Station 271, surface.

Genus 531. Spongocyrtis,^[36] Dunikowski.

Spongocyrtis, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, vol. xlv. p. 31.

Definition.—Archicorida with a spongy ovate shell, the wall of which is composed of irregular spongy wickerwork. Apex without horn.

The genus Spongocyrtis differs from most other Monocyrtida in the spongy structure of the shell, which is found in only very few other genera of Cyrtoidea, e.g., in Spongopyramis and Spongomelissa. It has been derived either from the similar Cyrtocalpis by development of irregular spongy wickerwork on the surface of the simple lattice-shell; or from Arachnocalpis (Pl. 98, fig. 13) by loss of the peristome.

1. Spongocyrtis montis ovis, Dunikowski.

Spongocyrtis montis ovis, Dunikowski, 1882, Denkschr. d. k. Akad. d. Wiss. Wien, vol. xlv. p. 31, Taf. vi. figs. 67, 68.

Shell broad, ovate, rough, spongy, thick-walled; length to the breadth = 4 : 3. Spongy framework very dense and dark, with very small roundish pores. Mouth constricted, with a short tubular peristome, about one-third as broad as the shell.

Dimensions.—Shell 0.35 long, 0.26 broad; mouth 0.08 broad.

Habitat.—Fossil in the Alpine Lias (Schafberg bei Salzburg, Dunikowski).

2. Spongocyrtis arachnoides, n. sp.

Shell ellipsoidal, spiny, spongy, thin-walled; length to the breadth = 3 : 2. Spongy framework loose and delicate, with irregular polygonal meshes and arachnoidal thread-like bars. Mouth constricted, without peristome, about one-fifth as broad as the shell. (Very similar to Arachnocalpis ellipsoides, Pl. 98, fig. 13, but without corona around the mouth.)

Dimensions.—Shell 0.32 long, 0.21 broad; mouth 0.04 broad.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

Subfamily 2. Archicapsida, Haeckel, 1881, Prodromus, p. 428.

Definition.—Cyrtocalpida, with the basal mouth of the shell fenestrated (vel Monocyrtida eradiata clausa).

Genus 532. Halicapsa,^[37] Haeckel, 1881 Prodromus, p. 429.

Definition.—Archicapsida with an apical horn.

The genus Halicapsa, and the following closely allied Archicapsa, represent together the small subfamily of Archicapsida, or of those Cyrtocalpida, in which the basal mouth of the simple shell is closed by a lattice plate. This may be the original state of this family, if it is derived from the Circospyrida (Circospyris, Dictyospyris) by loss of the sagittal constriction and the primary ring. But it is also possible that the Archicapsida have been partly derived from the Archicorida by secondary fenestration of the open mouth. The genus Halicapsa may be easily confounded with the similar Ellipsid Lithapium (compare p. 303, Pl. 14, figs. 8-10). The skeleton of both genera may be perfectly similar, the only distinction being the structure of the central capsule, which in Halicapsa is that of the Monopylea, in Lithapium that of the Peripylea.

Subgenus 1. Calpocapsa, Haeckel.

Definition.—Surface of the shell smooth or rough, but not spiny.

1. Halicapsa lithapium, n. sp. (Pl. 97, fig. 6).

Shell pear-shaped, rough, one and a half times as long as broad. Pores subregular, circular, twice as broad as the bars. Basal plate with four larger ovate cortinar pores (two larger cardinal and two smaller jugular), and with six smaller peripheral pores (fig. 6). Horn of the apex three-sided pyramidal, stout, half as long as the shell.

Dimensions.—Shell 0.16 long, 0.1 broad; horn 0.08 long.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

2. Halicapsa triglochin, n. sp. (Pl. 53, figs. 3, 4).

Shell ovate, rough, a little longer than broad. Pores regular, circular, hexagonally framed, of the same breadth as the bars. Basal plate (fig. 4) without larger pores. Horn pyramidal, stout, about half as long as the shell, with three short, horizontally divergent secondary spines at the base (possibly remnants of three original cortinar feet?)

Dimensions.—Shell 0.11 long, 0.09 broad; horn 0.06 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Halicapsa prunoides, n. sp.

Shell pear-shaped, tuberculate, a little longer than broad. Pores irregular, roundish, of different sizes. Basal plate with four larger and six smaller pores. Horn pyramidal, stout, about one-third as long as the shell. (May belong perhaps to the similar Prunoidea Lithapium, compare p. 303 and Pl. 14, figs. 8-10.)

Dimensions.—Shell 0.14 long, 0.12 broad; horn 0.05 long.

Habitat.—Fossil in Barbados.

Subgenus 2. Echinocapsa, Haeckel, 1881, Prodromus, p. 429.

Definition.—Surface of the shell spiny, covered with thorns, papillæ or larger spines.

4. Halicapsa papillata, n. sp.

Shell bottle-shaped, papillate, one and a half times as long as broad. Pores circular, much larger in the middle part than towards the poles. The elevated frames between them bear on the nodal points large blunt conical papillæ. Basal plate without larger pores. Horn three-sided pyramidal, one-third as long as the shell, gradually passing into the slender neck of the bottle.

Dimensions.—Shell 0.22 long, 0.15 broad; horn 0.07 long.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

5. Halicapsa pyriformis, Haeckel.

? Haliomma pyriforme, Bailey, 1856, Amer. Journ. Sci. and Arts, vol xxii. p. 1, pl. i. fig. 29.

Shell pear-shaped, a little longer than broad, covered with numerous short conical spines. Pores subregular, circular, of nearly equal size, twice as broad as the bars. Basal plate with four crossed larger ovate pores (two larger cardinal and two smaller jugular pores). Horn stout pyramidal, scarcely one-fourth as long as the shell.

Dimensions.—Shell 0.16 long, 0.14 broad; horn 0.04 long.

Habitat.—Fossil in Barbados, living in the North Pacific (Kamtschatka)?

6. Halicapsa hystrix, n. sp. (Pl. 53, figs. 5, 6).

Shell pear-shaped, subspherical, a little longer than broad, with scattered stout pyramidal spines about as long as the radius of the shell. Pores subregular, circular, three times as broad as the bars. Basal plate (fig. 6) without larger pores. Horn very large, pyramidal, longer than the shell.

Dimensions.—Shell 0.1 long, 0.09 broad; horn 0.13 long.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 533. Archicapsa,^[38] Haeckel, 1881, Prodromus, p. 428.

Definition.—Archicapsida without apical horn.

The genus Archicapsa differs from the preceding Halicapsa in the absence of the apical horn, and represents the simplest form among the Monocyrtida clausa, a simple, ovate, or pear-shaped shell without any appendages. The characteristic structure of the basal lattice-plate (with three or four large cortinar pores) makes it probable that Archicapsa has been derived either from Halicapsa, by loss of the horn, or directly from Dictyospyris, by reduction of the sagittal ring and constriction.

1. Archicapsa triforis, n. sp. (Pl. 53, figs. 1, 2).

Shell pear-shaped, smooth, one and a half times as long as broad. Pores subregular, circular, of about the same breadth as the bars. Basal plate (fig. 2) with three very large pores, three times as broad as the others (one odd sternal pore and two paired cardinal pores).

Dimensions.—Shell 0.09 long, 0.06 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Archicapsa quadriforis, n. sp.

Shell ovate, rough, a little longer than broad. Pores subregular, circular, twice as broad as the bars. Basal plate with four larger ovate cortinar pores (two smaller jugular and two larger cardinal pores).

Dimensions.—Shell 0.12 to 0.15 long, 0.1 to 0.12 broad.

Habitat.—Central Pacific, Station 265 to 268, depth 2700 to 2900 fathoms.

3. Archicapsa nonaforis, n. sp.

Shell pear-shaped, thorny, one and a half times as long as broad. Pores regular, circular, small, hexagonally framed, twice as broad as the bars. Basal plate with nine cortinar pores (three larger alternating with three pairs of smaller pores, as in Pl. 87, fig. 2).

Dimensions.—Shell 0.14 long, 0.09 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Section II. DICYRTIDA, Haeckel, 1862, Monogr. d. Radiol., pp. 280, 296.

Definition.—Cyrtoidea dithalamia, with two-jointed shell, being divided by a transverse collar stricture into an apical joint (or cephalis) and a basal joint (or thorax).

Synopsis of the three Families and six Subfamilies of Dicyrtida.

Family LXII. Tripocyrtida. Three radial apophyses.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth open,	1. Sethopilida.
		Mouth closed,	2. Sethoperida.
Family LXIII. Anthocyrtida. Numerous radial apophyses.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth open,	3. Sethophormida.
		Mouth closed,	4. Sethophænida.
Family LXIV. Sethocyrtida. No radial apophyses.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth open,	5. Sethocorida.
		Mouth closed,	6. Sethocapsida.

Family LXII. Tripocyrtida, n. fam.

Sethopilida et Sethoperida, Haeckel, 1881, Prodromus, pp. 431, 433.

Definition.—Dicyrtida triradiata. (Cyrtoidea with a two-jointed shell, divided by a transverse constriction into cephalis and thorax, and bearing three radial apophyses.)

The family Tripocyrtida, composed of the Sethopilida and Sethoperida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is two-jointed and bears three radial apophyses. The two subfamilies differ in the shape of the mouth, which in the Sethopilida is a simple wide opening, but in the Sethoperida is closed by a lattice-plate; the former are here divided into sixteen, the latter into eight different genera. Though probably the two shell-joints are not truly homologous in all Tripocyrtida, we call the first joint here, as in all Dicyrtida, the cephalis, and the second joint the thorax.

Numerous Tripocyrtida, living as well as fossil forms, were formerly described by Ehrenberg. His genera Dictyophimus, Clathrocanium, Lithomelissa, and Lychnocanium belong to the Sethopilida, and have the mouth open; his genera Lithopera and Lithochytris (partly) belong to the Sethoperida, and have the basal mouth closed by a lattice-plate. Many of these Tripocyrtida belong probably to the oldest forms of Dicyrtida, are nearly related to the Phormospyrida, and therefore of special phylogenetic interest, as was demonstrated by Bütschli (1882, loc. cit., pp. 514-519). This near relation to certain Spyroidea (Tripospyris, Acrospyris, &c.) is particularly striking in some forms of Clathrocanium, Lithomelissa, &c. Some other Tripocyrtida seem to possess a closer relation to certain Plectoidea (Plagoniscus, Plectaniscus), so mainly some forms of Tripocyrtis and Dictyophimus.

The cephalis, or the first joint of the shell, corresponds usually to the whole shell of the Zygospyrida and of numerous Monocyrtida, and exhibits various modifications of shape, which have been already described in these latter families. It is usually subspherical or hemispherical and armed with an apical horn. In a small number of genera the horn is lost, in some other genera multiplied. The cephalis is separated from the thorax not only externally by the collar constriction, but commonly also internally by a transverse horizontal fenestrated septum, which usually exhibits three or four characteristic cortinar pores. The central capsule, originally enclosed in the cephalis, develops usually three or four large pear-shaped cæcal sacs which pass through the cortinar pores and depend into the thorax (Pl. 55, figs. 2-11; Pl. 60, figs. 3-7, &c.).

The thorax in this family exhibits a great variety of interesting modifications, mainly in the development of the three radial apophyses arising from it. These may be either enclosed in the wall of the thorax as ribs, or arise as free wings, very often prolonged over the mouth as three terminal feet. Finally the three terminal feet only remain, whilst the original ribs are lost. The special ornamentation of these three apophyses exhibits an extraordinary variety and elegancy of structure, and many Tripocyrtida belong, no doubt, to the most graceful and admirable forms of Nassellaria.

Synopsis of the Genera of Tripocyrtida.

I. Subfamily Sethopilida. Terminal mouth of the thorax a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	A. Three radial ribs (or cortinar rods) partly or completely enclosed in the wall of the thorax. No latticed vertical cephalic wings.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	a. Three thoracic ribs prolonged into three terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Cephalis with a horn.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Feet solid,	534. Dictyophimus.
								Feet latticed,	535. Tripocyrtis.
						No horn, feet solid,			536. Sethopilium.
				b. Three thoracic ribs prolonged into three lateral wings.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Thorax perfectly latticed.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	With horn,	537. Lithomelissa.
								No horn,	538. Psilomelissa.
						Thorax with spongy framework,			539. Spongomelissa.
						Thorax with three large lateral holes between the three ribs,			540. Clathrocanium.
				c. Three thoracic ribs completely enclosed in the wall of the flat thorax	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Peristome simple, smooth,			541. Lamprodiscus.
						Peristome with a corona of spines,			542. Lampromitra.
		B. Three radial ribs enclosed in the wall of the thorax and connected with the cephalic horn by three latticed vertical wings.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	a. Thorax completely latticed	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	No frontal horn (four spines),			543. Callimitra.
						With frontal horn (five spines),			544. Clathromitra.
				b. Thorax with three large lateral holes between the three ribs. No frontal horn,					545. Clathrocorys.
		C. Three radial beams (or cortinar rods) perfectly free, not enclosed in the wall of the thorax.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Three beams outside the thorax, arising freely from the collar stricture (no cephalic hole),					546. Eucecryphalus.
				Three beams inside the thorax. Cephalis with a large apical hole,					547. Amphiplecta.
		D. Three radial terminal feet on the peristome (the three original lateral ribs are lost).			$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Feet solid,			548. Lychnocanium.
						Feet latticed,			549. Lychnodictyum.
II. Subfamily Sethoperida. Terminal mouth of the thorax closed by a lattice-plate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Three divergent ribs (or cortinar rods) enclosed either in the wall or in the cavity of the thorax.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Three ribs enclosed in the lattice-wall of the thorax,			550. Sethopera.
						Three internal rods in the cavity of the thorax,			551. Lithopera.
		Three divergent free lateral wings (as prolongation of the three ribs) on the sides of the thorax.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Three solid lateral spines.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Cephalis with horn,	552. Micromelissa.
								No horn,	553. Peromelissa.
						Three latticed lateral wings. With horn,			554. Sethomelissa.
		Three free terminal feet (on the base of the thorax).			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Three feet solid,			555. Tetrahedrina.
						Three feet latticed.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell without external mantle,	556. Sethochytris.
								Shell with an arachnoidal mantle,	557. Clathrolychnus.

Subfamily 1. Sethopilida, Haeckel, 1881, Prodromus, p. 431.

Definition.—Tripocyrtida, with the basal mouth of the shell open (vel Dicyrtida triradiata aperta).

Genus 534. Dictyophimus,^[39] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 53.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three complete thoracic ribs, prolonged into three solid divergent feet on the peristome. Cephalis with an apical horn.

The genus Dictyophimus, comprising many common species, may be regarded as the common ancestral form of all sethopilida, and therefore also of the whole family of Dicyrtida. The cephalis bears an apical horn, and the thorax three ribs, which are prolonged over the open mouth into three solid feet. Dictyophimus may be derived either from Euscenium or Peridium (Archiperida), or from Tripospyris (Zygospyrida), or from Plectaniscus (Plectanida), by development of lattice-work between the three terminal feet, which therefore become thoracic ribs.

Subgenus 1. Dictyophimium, Haeckel.

Definition.—Shell smooth or rough, without prominent spines on the edges of the three thoracic ribs. (Commonly one single horn on the cephalis.)

1. Dictyophimus sphærocephalus, n. sp. (Pl. 57, fig. 10).

Shell smooth, with a deep collar stricture, separating two joints of nearly equal size. Cephalis subglobular, rough, with a stout pyramidal horn of half the length, and regular, circular, hexagonally framed pores. Thorax nearly three-sided prismatic, smooth, with three stout, little divergent or nearly parallel ribs, which are prolonged into conical subvertical feet half as long. Thoracic pores irregular, roundish.

Dimensions.—Cephalis 0.08 long, 0.08 broad; thorax 0.08 long, 0.08 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Dictyophimus tripus, Haeckel.

Dictyophimus tripus, Haeckel, 1862, Monogr. d. Radiol., p. 306, Taf. vi. fig. 1.

Shell with a slight collar stricture, separating two joints of slightly different size. Cephalis nearly ellipsoidal, large, with a slender conical horn of the same length. Thorax truncate three-sided pyramidal, with three strongly divergent ribs, which are prolonged into three slender conical feet of about the same length. Pores irregular, roundish, of variable size.

Dimensions.—Cephalis 0.032 long, 0.028 broad; thorax 0.34 long, 0.064 broad.

Habitat.—Mediterranean (Messina), Atlantic (Canary Islands), surface.

3. Dictyophimus plectaniscus, n. sp. (Pl. 61, figs. 8, 9).

Shell flat, pyramidal, smooth, with distinct collar stricture. Cephalis hemispherical, with a conical horn of the same length and numerous small regular pores. Thorax flat, triangular, pyramidal, with three widely divergent ribs, which are prolonged into three cylindrical feet of the same length. Thoracic pores fifteen, very large, subregular, roundish, disposed in two transverse girdles, the inner with six, the outer with nine pores; five pores between every two ribs.

Dimensions.—Cephalis 0.04 long, 0.06 broad; thorax 0.08 long, 0.18 broad.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

4. Dictyophimus craticula, Ehrenberg.

Dictyophimus craticula, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. v. figs. 4, 5. Dictyophimus craticula, Bütschli, 1882, Zeitschr. f. Wiss. Zool., vol. xxxvi. p. 515, Taf. xxxiii. fig. 35.

Shell flat, pyramidal, very similar to the preceding species, but differing in the rudimentary horn, which is smaller than half the cephalis, and in the length of the three cylindrical feet, which are twice to three times as long as the shell. The nine inferior large pores of the thorax are twice to three times as large as the six superior pores. The basal peristome is commonly thorny.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.1 long, 0.2 broad.

Habitat.—Fossil in Barbados.

5. Dictyophimus pyramis, n. sp. (Pl. 61, fig. 16).

Shell regular, pyramidal, with flat collar stricture. Relative length of the two joints = 1 : 4, breadth = 2 : 6. Cephalis hemispherical, with a stout pyramidal horn of the same length. Thorax triangular pyramidal, with three prominent ribs, which are prolonged into three slender pyramidal feet, half as long. Pores small and very numerous, subregular, circular.

Dimensions.—Cephalis 0.03 long, 0.05 broad; thorax 0.1 long, 0.15 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

6. Dictyophimus challengeri, Haeckel.

Dictyophimus challengeri, Haeckel, 1878, Protistenreich, p. 47, fig. 35.

Shell campanulate, with sharp collar stricture. Relative length of the joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a stout pyramidal horn of twice the length, and numerous very small pores. Thorax nearly hemispherical, with three vaulted bosoms between the three decurrent ribs, which are prolonged into three nearly parallel and vertical feet of about the same length. Pores subregular, circular, of medium size. This species is very similar to Lychnodictyum challengeri, Haeckel, but differs in the smaller straight horn and the longer solid feet, which are not fenestrated.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.13 broad.

Habitat.—Tropical Atlantic, Station 347, surface.

7. Dictyophimus lasanum, n. sp. (Pl. 61, fig. 5).

Shell nearly pear-shaped, with distinct collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis hemispherical, with a conical horn of the same length. Thorax nearly spherical, on both poles truncate and constricted, with three decurrent curved ribs and small regular circular pores. The prolongations of the ribs form three divergent pyramidal straight feet, nearly as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.09 long, 0.09 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

8. Dictyophimus longipes, n. sp. (Pl. 61, fig. 3).

Shell three-sided pyramidal, with distinct collar stricture. Relative length of the two joints = 1 : 4, breadth = 2 : 6. Cephalis hemispherical, with a rudimentary pyramidal horn, scarcely one-fourth as long; and with small circular regular pores. Thorax with larger irregular pores, and three vaulted bosoms between the three decurrent ribs, which are prolonged into three very long and slender prismatic feet, S-shaped, curved, and twice to three times as long as the shell.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.09 long, 0.13 broad.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

9. Dictyophimus gracilipes, Bailey.

Dictyophimus gracilipes, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii. p. 4, pl. i. fig. 8.

Shell three-sided pyramidal, with a deep collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis hemispherical, with a thin horn of the same length. Thorax with three curved ribs, which are prolonged into three divergent angular feet of the same length. Pores irregular roundish.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.05 long, 0.08 broad.

Habitat.—North Pacific, Station 240, surface, Kamtschatka (Bailey).

10. Dictyophimus cortina, n. sp. (Pl. 61, fig. 1).

Shell three-sided pyramidal, with distinct collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a pyramidal horn of half the length. Thorax with much larger irregular roundish pores and three prominent ribs, which are prolonged into three stout, club-shaped, strongly divergent feet of the same length. Mouth widely open, elegantly coronate, with a circle of numerous small cilia.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.08 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

11. Dictyophimus arabicus, Haeckel.

Lychnocanium arabicum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 296, Taf. x. fig. 3.

Shell smooth, three-sided pyramidal, with deep collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a slender horn of the same length. Thorax with much larger, irregular roundish pores, and three widely divergent ribs, which are prolonged into three slender, somewhat recurved feet of about the same length.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.07 long, 0.09 broad.

Habitat.—Indian Ocean, Zanzibar (Pullen), depth 2200 fathoms.

12. Dictyophimus platycephalus, n. sp. (Pl. 60, figs. 4, 5).

Shell smooth, flat, three-sided pyramidal, with distinct collar stricture. Relative length of the two joints = 1 : 3, breadth = 3 : 9. Cephalis flat, cap-shaped, three times as broad as long, with a slender conical horn of the same length. Thorax flatly vaulted, with much larger, irregular roundish, double-edged pores, and three widely divergent ribs, which are prolonged into three slender conical feet of the same length. Central capsule in the cephalis flat, discoidal, with a discoidal nucleus of half the size, and with four large pear-shaped cæcal sacs depending into the thorax, each of which contains a large oil globule (fig. 4).

Dimensions.—Cephalis 0.02 long, 0.07 broad; thorax 0.06 long, 0.18 broad.

Habitat.—North Atlantic, Canary Islands (Lanzerote), Haeckel, surface.

13. Dictyophimus brandtii, n. sp. (Pl. 60, fig. 6).

Shell smooth, flat, three-sided pyramidal, with deep collar stricture, very similar to the preceding species. Relative length of the two joints = 1 : 3, breadth = 2 : 7. Cephalis hemispherical, with a slender conical horn of twice the length. Thorax flatly vaulted, with irregular polygonal pores and thin bars; and with three widely divergent ribs, which are prolonged into three slender prismatic feet of thrice the length. In fig. 6 the shell is seen from the base and exhibits very distinctly the collar septum with its four large meshes, two minor jugular and two major cardinal pores.

Dimensions.—Cephalis 0.03 long, 0.07 broad; thorax 0.08 long, 0.2 broad.

Habitat.—North Pacific, Station 236, surface.

14. Dictyophimus lucerna, Haeckel.

Lychnocanium lucerna, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 6; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 80, Taf. viii. fig. 3. Lychnocanium lucerna, Haeckel, 1862, Monogr. d. Radiol., p. 311.

Shell smooth, three-sided pyramidal, with slight collar stricture. Relative length of the two joints = 1 : 4, breadth = 1 : 4. Cephalis hemispherical, with a thick conical horn of twice the length. Thorax with small regular, circular pores and three flat sides; between these arise three rounded ribs, which are prolonged into three short, conical, divergent feet, one-third as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.025 broad; thorax 0.08 long, 0.08 broad.

Habitat.—Fossil in Barbados.

15. Dictyophimus hamosus, Haeckel.

Lychnocanium hamosum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. vii. fig. 9.

Shell pear-shaped, rough, with deep collar stricture. Relative length of the two joints = 1 : 2, breadth = 1 : 3. Cephalis subglobular, with a conical horn of twice the length. Thorax with small, regular, circular pores, and with three prominent ribs, prolonged into three vertical prismatic feet, which are about as long as the shell, parallel or a little convergent towards the distal end, with recurved teeth or hooks at the lateral edges.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.04 long, 0.06 broad.

Habitat.—Fossil in Barbados.

16. Dictyophimus tridentatus, Haeckel.

Lychnocanium tridentatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 4.

Shell smooth, three-sided pyramidal, with deep collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a conical horn of the same length, and some small accessory thorns. Thorax tetrahedral, with three smooth hyaline walls, bearing only a single series of small pores on each side of the three prominent ribs, which are prolonged into three strong prismatic curved feet of twice the length, with the convexity external. A group of small pores and a strong triangular tooth at the base of each foot.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.08 broad.

Habitat.—Fossil in Barbados.

Subgenus 2. Lamprotripus, Haeckel, 1881, Prodromus, p. 432.

Definition.—Shell spiny or thorny, with prominent spines on the edges of the three thoracic ribs. (Commonly one larger and a few smaller horns or spines on the cephalis.)

17. Dictyophimus triserratus, n. sp. (Pl. 61, fig. 17).

Shell three-sided pyramidal, with slight collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis small, subspherical, with a large pyramidal horn three times as long. Thorax with much larger, irregular roundish, double-edged pores, and three prominent, serrate ribs, which are prolonged into three pyramidal strongly divergent feet of the same length.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.09 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

18. Dictyophimus bicornis, n. sp.

Shell thorny, with deep collar stricture. Relative length of the two joints = 2 : 3, breadth = 2 : 3. Cephalis nearly as large as the thorax, subglobular, with numerous small, circular pores, and two divergent pyramidal horns of half the length (a major occipital and a minor frontal horn). Thorax three-sided pyramidal, with larger irregular pores and three serrate ribs, which are prolonged into three prismatic spiny feet of half the length. (Differs from the similar Dictyophimus sphærocephalus, Pl. 57, fig. 10, mainly in the double horn and the spinulate feet.)

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.08 long, 0.07 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

19. Dictyophimus pocillum, Ehrenberg.

Dictyophimus pocillum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. v. fig. 6.

Shell thorny, with distinct collar stricture. Relative length of the two joints = 1 : 5, breadth = 1 : 5. Cephalis nearly spherical, with numerous small conical spines. Thorax flat, three-sided pyramidal with large, irregular, roundish pores, and three strong, widely divergent, spinulate ribs, which are prolonged into three prismatic spinulate feet of the same length.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.15 long, 0.15 broad.

Habitat.—Fossil in Barbados.

20. Dictyophimus cienkowskii, n. sp. (Pl. 60, fig. 1).

Lamprotripus squarrosus, Haeckel, 1881, Prodromus et Atlas.

Shell spiny, flatly pyramidal, with slight collar stricture. Relative length of the two joints = 1 : 3, breadth = 2 : 6. Cephalis flat, cap-shaped, three times as long as broad, with numerous bristle-shaped spines three times as long. Thorax also spiny, with irregular, very large, polygonal meshes and thin bars; its three ribs prolonged into three very long and thin, widely divergent, prismatic feet, bearing numerous long spines on the three edges.

Dimensions.—Cephalis 0.025 long, 0.05 broad; thorax 0.075 long, 0.15 broad.

Habitat.—North Pacific, Station 250, surface.

21. Dictyophimus bütschlii, n. sp. (Pl. 60, fig. 2).

Lamprotripus horridus, Haeckel, 1881, Prodromus et Atlas.

Shell spiny, flatly pyramidal, with deep collar stricture. Relative length at the two joints = 1 : 2, breadth = 1 : 5. Cephalis subspherical, with numerous long, bristle-shaped spines and a larger ramified horn. Thorax also spiny, flatly vaulted, with large, subregular, hexagonal meshes and thin bars; its three spiny ribs prolonged into three very long and thin, prismatic, widely divergent feet, twice to four times as long as the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

Habitat.—South Pacific, Station 284, surface.

22. Dictyophimus hertwigii, n. sp. (Pl. 60, fig. 3).

Lamprotripus spinosus, Haeckel, 1881, Prodromus et Atlas.

Shell spiny, flatly pyramidal with sharp collar stricture. Relative length of the two joints = 1 : 2, breath = 1 : 5. Cephalis subspherical, with irregular roundish pores, numerous small spines and a large, oblique, prismatic horn of the same length, bearing on its distal end a bunch of small divergent spines. Thorax pyramidal, with larger irregular polygonal pores and thin bars; its three strong, widely divergent ribs spiny, straight, and prolonged into three prismatic slender feet of the same length. Central capsule with three lobes depending into the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

Habitat.—Central Pacific, Stations 270 to 274, surface.

Genus 535. Tripocyrtis,^[40] n. gen.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three complete thoracic ribs, prolonged into three latticed divergent feet on the peristome. Cephalis with an apical horn.

The genus Tripocyrtis has been derived from the preceding Dictyophimus by complete fenestration of the three basal feet, which throughout their whole length become united by complete lattice-work. This genus is closely allied to Plectaniscus.

1. Tripocyrtis plagoniscus, n. sp. (Pl. 60, fig. 10).

Cephalis subspherical, with large, roundish meshes and a stout, three-sided pyramidal, irregularly branched horn of twice the length. Thorax with a small number of large, irregular, polygonal meshes and three stout curved ribs about as long as the cephalic horn.

Dimensions.—Cephalis 0.06 long, 0.07 broad; thorax 0.11 long, 0.16 broad.

Habitat.—Central Pacific, Station 266, surface.

2. Tripocyrtis tripodiscus, n. sp.

Cephalis subspherical, with small, polygonal pores and a large, arborescent, vertical horn of thrice the length, bearing numerous ramified branches. Thorax with three straight, widely divergent ribs, of the same length as the horn, connected by a delicate, arachnoidal framework with irregular, polygonal meshes.

Dimensions.—Cephalis 0.04 long, 05 broad; thorax 0.12 long, 0.18 broad.

Habitat.—Central Pacific, Station 269, surface.

3. Tripocyrtis plectaniscus, n. sp. (Pl. 60, fig. 9).

Cephalis subspherical, with small roundish pores, and a stout, three-sided pyramidal, denticulate horn of the same length. Thorax with three little divergent and curved ribs, twice as long as the horn, in the upper half with smaller, in the lower half with larger, polygonal, irregular meshes.

Dimensions.—Cephalis 0.05 long, 0.06 broad; thorax 0.1 long, 0.12 broad.

Habitat.—Central Pacific, Station 264, surface.

Genus 536. Sethopilium,^[41] Haeckel, 1881, Prodromus, p. 431.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three complete thoracic ribs, which are prolonged into three solid divergent feet on the peristome. Cephalis smooth, without a horn.

The genus Sethopilium differs from its probable ancestral form Dictyophimus by the complete loss of the cephalic horn, and of the collar septum between both joints, which are only separated by the slight external collar stricture.

1. Sethopilium orthopus, n. sp. (Pl. 97, fig. 8).

Shell smooth, with sharp collar stricture, Relative length of the two joints = 5 : 4, breadth = 7 : 6. Cephalis large, subspherical, with numerous regular circular pores, twice as broad as the bars. Thorax with three stout, straight, widely divergent ribs, prolonged into three straight pointed feet of the same length. Between every two ribs, in the centre of the collar stricture, a single large triangular mesh, and beyond this three to six rows of smaller irregular meshes.

Dimensions.—Cephalis 0.05 long, 0.07 broad; thorax 0.04 long, 0.06 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Sethopilium cyrtopus, n. sp.

Shell smooth, with sharp collar stricture. Relative length of the two joints = 4 : 6, breadth = 7 : 11. Cephalis hemispherical, with large irregular roundish pores, four times as broad as the bars. Thorax with three stout, curved, widely divergent ribs, prolonged into three cylindro-conical, curved feet of twice the length, which are convex in the proximal half, concave in the distal half. Between every two ribs, beyond the collar stricture, two large ovate meshes, and beyond this two rows of smaller irregular meshes.

Dimensions.—Cephalis 0.04 long, 0.07 broad; thorax 0.05 long, 0.11 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Sethopilium macropus, n. sp. (Pl. 97, fig. 9).

Shell smooth, with slight collar stricture. Relative length of the two joints = 4 : 7, breadth = 6 : 13. Cephalis hemispherical, with irregular double-contoured pores, about as broad as the bars. Thorax with three very stout, carved, widely divergent ribs, prolonged into three curved, cylindrical, very long feet, which are three to four times as long as the shell, and convex on the outside. Between every two ribs, beyond the collar stricture, two large broad meshes, and beyond this two or three rows of smaller meshes.

Dimensions.—Cephalis 0.04 long, 0.06 broad; thorax 0.07 long, 0.13 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 537. Lithomelissa,^[42] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three free lateral wings, or solid spines arising from the sides of the thorax. No terminal feet. Cephalis with one or more horns.

The genus Lithomelissa, containing numerous and widely distributed forms, may like Dictyophimus be regarded as one of the most primitive and ancient forms of Dicyrtida. It differs from the latter by the lateral (not terminal) position of the three thoracic feet, and may be derived either from Dictyophimus (by secondary development of intrapedal network towards the mouth, on the inside of the three feet) or directly from Tripospyris by similar formation of thoracic network beyond the collar stricture, outside the base of the three divergent feet and pierced by the latter. As the species of this genus are numerous, it may perhaps be better to divide it into two or three genera: Acromelissa, with a single horn, Micromelissa, with two horns, and Sethomelissa, with three or more horns.

Subgenus 1. Acromelissa, Haeckel, 1881, Prodromus, p. 431.

Definition.—Cephalis with a single occipital horn.

1. Lithomelissa macroptera, Ehrenberg.

Lithomelissa macroptera, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. figs. 9, 10.

Shell smooth, with distinct collar stricture. Relative length of the two joints = 4 : 5, breadth = 3 : 4. Cephalis ovate, with a stout, excentric, vertical, pyramidal horn of the same length. Thorax little larger, ovate, truncate. Both joints with very small and scattered pores. Three divergent ribs arise from the base of the cephalic horn, and are prolonged over the major part of the thorax; their under free part arises from the middle part of the thorax and is as long as the horn, straight, pyramidal. Mouth truncate, little constricted.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.05 long, 0.04 broad.

Habitat.—Fossil in Barbados.

2. Lithomelissa ehrenbergii, Bütschli.

Lithomelissa ehrenbergii, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 517, Taf. xxxiii. fig. 21a, b.

Lithomelissa macroptera, var., Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 8.

(?) Lophophæna capito, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 6.

(?) Lophophæna galeata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 12.

Shell rough, with distinct collar stricture. Relative length of the two joints = 4 : 2, breadth = 3 : 4. Cephalis ovate, with a stout excentric, oblique, pyramidal horn of half the length. Thorax little shorter, truncate, conical. Both joints with regular circular pores, of the same breadth as the bars. Three divergent conical feet, as long as the cephalis, arise below the collar stricture. Mouth truncate, not constricted.

Dimensions.—Cephalis 0.08 long, 0.06 broad; thorax 0.04 long, 0.08 broad.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms; fossil in Barbados.

3. Lithomelissa macroceras, n. sp.

Shell spiny, with sharp collar stricture. Relative length of the two joints = 5 : 7, breadth = 5 : 6. Cephalis spherical, with a large pyramidal horn of twice the length. Thorax little longer, ovate, truncate. Both joints with regular circular pores, three times as broad as the bars. Three divergent pyramidal feet, twice as long as the cephalis, arise from the middle part of the thorax. Mouth constricted, half as broad as the thorax.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.07 long, 0.06 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

4. Lithomelissa mitra, Bütschli.

Lithomelissa mitra, Bütschli, 1881, Zeitschr. f. wiss. Zool., p. 518, Taf. xxxiii. fig. 24.

Shell smooth, with distinct collar stricture. Relative length of the two joints = 5 : 4, breadth = 4 : 5. Cephalis ovate, with a slender, straight, vertical, pyramidal horn of the same length. Thorax ovate, truncate, of about the same size. Both joints with very small and numerous pores, as broad as the bars. Three feet arising from the middle part of the thorax, very small, rudimentary, pyramidal, about as long as broad. Mouth truncate, little constricted.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.04 long, 0.05 broad.

Habitat.—Fossil in Barbados.

5. Lithomelissa pycnoptera, n. sp.

Shell rough, papillate, with slight collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis small, hemispherical, with very small pores and a slender, straight, conical horn of twice the length. Thorax subconical, with regular circular, hexagonally framed pores, as broad as the bars. From its lower half arise three divergent, very strong feet, pyramidal, as long as the thorax, and three times as long as broad.

Dimensions.—Cephalis 0.03 diameter, thorax 0.1 diameter.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

6. Lithomelissa microstoma, n. sp.

Shell papillate, with slight collar stricture. Relative length of the two joints = 1 : 5, breadth = 1 : 5. Cephalis small, hemispherical, with a conical horn of twice the length. Thorax subspherical, with subregular circular pores, three times as broad as the bars. From its middle part arise three divergent, stout, conical feet, of half the length, and twice as long as broad. Mouth small, strongly constricted, one-fourth to one-third as broad as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.15 diameter.

Habitat.—Fossil in Barbados.

7. Lithomelissa amphora, Stöhr.

Lithomelissa amphora, Stöhr, 1880, Palæontograph, vol. xxvi. p. 100, Taf. iii. fig. 11.

Shell smooth, with sharp collar stricture. Relative length of the two joints = 1 : 5, breadth = 2 : 4. Cephalis small, hemispherical, with a cervical horn of the same length. Thorax ovate, with small regular circular pores, twice as broad as the bars. From its upper half arise three divergent, slender, conical feet, only one-fourth as long. Mouth constricted, with a hyaline peristome, half as broad as the thorax.

Dimensions.—Cephalis 0.013 long, 0.026 broad; thorax 0.063 long, 0.053 broad.

Habitat.—Fossil in tertiary rocks of Sicily; Grotte (Stöhr).

Subgenus 2. Micromelissa, Haeckel, 1881, Prodromus, p. 433 (sensu emendato).

Definition.—Cephalis with two divergent horns, a superior occipital horn and an inferior frontal horn.

8. Lithomelissa thoracites, Haeckel.

Lithomelissa thoracites, Haeckel, 1862, Monogr. d. Radiol., p. 301, Taf. vi. figs. 2-8. Lithomelissa thoracites, R. Hertwig, 1879, Organism. d. Radiol., p. 76, Taf. viii. fig. 1.

Shell smooth, with deep collar stricture. Cephalis ovate, with two divergent, slender, conical horns, of about half the length; a major oblique occipital horn on the posterior face, and a minor, nearly horizontal horn above the collar stricture, on the anterior face. Thorax about as large as the cephalis, truncate, ovate. Pores of both joints irregular, roundish, of different sizes. From the upper half of the thorax, below the collar stricture, there arise three slender, conical divergent feet, about as long as the cephalis. Mouth truncate, wide open, not constricted. On the numerous varieties of this common species compare my Monograph, on the structure of the ovate central capsule (enclosed in the cephalis), Hertwig, loc. cit.

Dimensions.—Cephalis 0.05 to 0.08 long, 0.04 broad; thorax 0.03 to 0.05 long, 0.05 to 0.07 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

9. Lithomelissa mediterranea, J. Müller.

Lithomelissa mediterranea, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 45, Taf. vi. fig. 11. Lithomelissa mediterranea, Haeckel, 1862, Monogr. d. Radiol., p. 302.

Shell smooth, with sharp collar stricture. Relative length of the two joints = 4 : 5, breadth = 4 : 5. Cephalis campanulate, conical, with two divergent small conical horns, a major occipital subvertical horn near the summit, and a minor sub-horizontal frontal horn near the collar stricture. Thorax truncate, ovate, little larger than the cephalis. From its lower part there arise three short conical, divergent feet, scarcely half as long as the cephalis (in Müller's figure one of them is seen shortened, opposite to the frontal horn). Pores irregular, roundish, much smaller in the cephalis than in the thorax. Mouth wide open, not constricted.

Dimensions.—Cephalis 0.04 diameter, thorax 0.05 diameter.

Habitat.—Mediterranean (French shore), J. Müller, surface.

10. Lithomelissa bicornis, Ehrenberg.

Lithomelissa bicornis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. ii. fig. 7.

Shell smooth, with deep collar stricture. Relative length of the two joints = 1 : 3, breadth = 1 : 2. Cephalis hemispherical, with two divergent, stout and straight, pyramidal horns; a larger occipital horn sub-vertical near the summit, and a smaller oblique frontal horn near the collar stricture. Thorax subspherical, twice as large, with larger irregular, roundish pores. From its lower half there arise three divergent curved pyramidal feet of about the same length. Mouth constricted, only one-third as broad as the thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 diameter.

Habitat.—Atlantic, Stations 348 to 353, surface.

11. Lithomelissa haeckelii, Bütschli.

Lithomelissa haeckelii, Bütschli, 1883, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 517, Taf. xxxiii. fig. 23, a, b.

Shell rough, with sharp collar stricture. Relative length of the two joints = 6 : 5, breadth = 6 : 7. Cephalis subspherical, large, with two divergent horns, a very large, oblique pyramidal occipital horn on the summit, and a very small frontal horn on the middle of the forehead. Thorax campanulate, little larger than the cephalis, with regular circular pores of twice the breadth. From the upper part of the thorax, below the collar stricture, there arise three stout, divergent, angular, semi-lunar feet, about as long as the shell. Mouth wide open, not constricted.

Dimensions.—Cephalis 0.6 long, 0.6 broad; thorax 0.05 long, 0.07 broad.

Habitat.—Tropical Atlantic, Station 347, depth 2260 fathoms; fossil in Barbados.

12. Lithomelissa bütschlii, n. sp. (Pl. 56, fig. 1).

Shell smooth, with slight collar stricture. Relative length of the two joints = 5 : 6, breadth = 4 : 5. Cephalis ovate, large, with two small conical horns, which are opposed nearly horizontally, in the upper part of the cephalis; an anterior frontal and a posterior occipital horn. Thorax ovate, truncate, little larger. Pores of both joints irregular, roundish, of very different sizes. From the middle part of the thorax there arise three short conical divergent feet. (In the figured specimen there were some accessory thorns; in another specimen, found afterwards, the surface was quite smooth, but the two horns and the three feet much larger, half as long as the cephalis.)

Dimensions.—Cephalis 0.05 long, 0.04 broad; 0.06 long, 0.05 broad.

Habitat.—Central Pacific, Stations 266 to 274, depth 2350 to 2925 fathoms.

Subgenus 3. Sethomelissa, Haeckel, 1881, Prodromus, p. 431.

Definition.—Cephalis with three, four, or more horns, a primary occipital, a secondary frontal, and one or more accessory parietal horns.

13. Lithomelissa corythium, Ehrenberg.

Lithomelissa corythium, Ehrenberg, 1875, Abhandl. d.k. Akad. d. Wiss. Berlin, p. 78, Taf. iii, fig. 12.

Shell smooth, with slight collar stricture. Relative length of the two joints = 4 : 3, breadth = 4 : 5. Cephalis campanulate, with three short conical horns on the summit. Thorax flat and wide. From its upper part below the collar stricture, there arise three divergent, pyramidal feet, fenestrated at the base, about as long as the shell. Mouth wide open. (The specimen figured by Ehrenberg was an incomplete one.)

Dimensions.—Cephalis 0.04 in diameter, thorax 0.03 long, 0.05 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; fossil in Barbados.

14. Lithomelissa decacantha, n. sp. (Pl. 56, fig. 2).

Sethomelissa decacantha, Haeckel, 1881, Prodromus et Atlas.

Shell smooth, with deep collar stricture, and with ten prismatic spines of nearly equal size and similar form. Relative length and breadth of the two joints about equal. Cephalis ovate, in the upper half hyaline, in the lower half with few scattered pores; in the equator with four prismatic horns of the same length, which diverge upwards; three of them are placed in the same meridional planes as the three wings and the three feet of the thorax (one occipital and two parietal); the fourth (frontal) horn is opposed to the occipital. Thorax campanulate, three-edged, with three vertical prominent feet (directed downward) and three horizontal wings, arising from their knees. Mouth wide open, not constricted.

Dimensions.—Cephalis 0.05 diameter; thorax 0.05 long, 0.06 broad.

Habitat.—Equatorial Atlantic, Station 347, surface.

Genus 538. Psilomelissa,^[43] Haeckel, 1881, Prodromus, p. 431.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three free lateral wings, or solid spines arising from the sides of the thorax. No terminal feet. Cephalis smooth, without a horn.

The genus Psilomelissa has the same formation of the shell as the nearly allied preceding genus Lithomelissa, and may be derived from it by reduction and loss of the cephalic horn. The cephalis is quite bare.

1. Psilomelissa galeata, Haeckel.

Dictyocephalus galeatus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 289, Taf. vii. fig. 25.

Shell smooth, with sharp collar stricture. Relative length of the two joints = 5 : 3, breadth = 4 : 5. Cephalis ovate, with numerous irregular, roundish pores. Thorax truncate, conical, with a few small pores. From its upper part (below the collar stricture) there arise three thin, bristle-shaped, widely divergent wings, about as long as the cephalis. Mouth widely open.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.03 long, 0.05 broad.

Habitat.—Western Tropical Pacific, Stations 200 to 225, surface.

2. Psilomelissa phalacra, n. sp.

Shell smooth, with deep collar stricture. Relative length of the two joints = 5 : 6, breadth = 4 : 4. Cephalis ovate, hyaline, with few small pores only in the lower third. Thorax cylindrical, truncate, with small irregular, roundish pores. From its upper third there arise below the stricture three club-shaped, nearly horizontally divergent wings, as long as the thorax. The cephalis and the three feet are similar to those of Peromelissa phalacra, (Pl. 57, fig. 11); but the cylindrical thorax with irregularly scattered pores is completely different, and exhibits a truncate, wide open mouth.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.04 broad.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

3. Psilomelissa hertwigii, Haeckel.

Lithomelissa hertwigii, Bütschli, 1882, Zeitschr. f. wiss. Zool., p. 517, Taf xxxiii. fig. 22, a, b.

Shell rough, with obliterated collar stricture. Length of the two joints = 4 : 4, breadth = 5 : 5. Cephalis hemispherical. Thorax little larger, cylindrical. From its upper half there arise three very strong pyramidal divergent wings, about as long as the shell. Pores of both joints very small and numerous, circular. Mouth truncate, wide open.

Dimensions.—Cephalis 0.04 long, 0.06 broad; thorax 0.04 long, 0.05 broad.

Habitat.—Fossil in Barbados.

4. Psilomelissa calvata, n. sp. (Pl. 56, fig. 3).

Shell smooth, with sharp collar stricture. Length of the two joints = 7 : 5, breadth = 5 : 6. Cephalis ovate, large, with subregular, circular, double-contoured pores. Thorax smaller, ovate, with very irregular, roundish pores of different sizes. From its upper third there arise three conical, slender, widely divergent spines or wings of the same length. (In fig. 3 the cephalis with the three wings is alone represented.)

Dimensions.—Cephalis 0.07 long, 0.05 broad; thorax 0.05 long, 0.06 broad.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

5. Psilomelissa sphærocephala, n. sp.

Shell rough, with deep collar stricture. Length of the two joints = 1 : 2, breadth = 1 : 3. Cephalis spherical. Thorax cap-shaped, flat and broad. From its upper half there arise three pyramidal wings, half as long, fenestrated at the base and nearly horizontally divergent. Mouth constricted, half as broad as the thorax.

Dimensions.—Cephalis 0.03 diameter; thorax 0.06 long, 0.09 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Genus 539. Spongomelissa,^[44] n. gen.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three free lateral wings, or solid spines arising from the sides of the thorax. No terminal feet. Cephalis with one or more horns.

The genus Spongomelissa differs from its ancestral genus Lithomelissa only in the development of spongy framework in the shell-wall—a very rare production in the Cyrtoidea (compare Peripyramis, p. 1162, and Spongocyrtis, p. 1188).

1. Spongomelissa spongiosa, Haeckel.

Lithomelissa spongiosa, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. pp. 519, 539, Taf. xxxiii. fig. 25, a, b, c.

Shell of dense spongy structure, with a deep collar stricture. The subspherical cephalis and the truncate abdomen of nearly equal size, both with irregular delicate spongy framework. Mouth wide open. Cephalis with a large vertical apical and a small oblique frontal horn. Thorax with three very stout, three-sided prismatic widely divergent lateral wings, which are covered with numerous irregularly ramified branches; the spongy framework arises by communication of the delicate branches.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.04 long, 0.06 broad.

Habitat.—Fossil in Barbados.

Genus 540. Clathrocanium,^[45] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 829.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three prominent lateral ribs on the thorax, alternating with three large holes (or thoracic gates). Cephalis with a horn.

The genus Clathrocanium is nearly allied to Dictyophimus and Lithomelissa, and, together with these two genera, may be regarded as surviving representatives of the oldest and most primitive forms of Dicyrtida. It differs from the latter mainly in the incomplete fenestration of the shell, three large interradial holes remaining between the three perradial thoracic ribs. It may therefore be derived either from Euscenium or from Tripospyris by the development of a terminal lattice-band between the three feet. Clathrocanium may be divided into two different subgenera: Clathrocanidium, with simple horn and smooth mouth, and Clathrocorona, with fenestrated horn and coronated mouth.

Subgenus 1. Clathrocanidium, Haeckel.

Definition.—Horn of the cephalis simple, not fenestrated. Peristome smooth.

1. Clathrocanium squarrosum, Ehrenberg.

Clathrocanium squarrosum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. vii. fig. 5.

Cephalis campanulate, with irregular roundish pores and a pyramidal horn of the same length, bearing at the apex three short branches. Length of the two joints 2 : 3, breadth = 2 : 6. Thorax with three simple, prismatic, thin ribs, which are twice as long as the cephalis, separated by large triangular holes and connected only at the distal end by a small triangular ring of delicate lattice-work. Peristome smooth, wide, as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.12 broad.

Habitat.—Western Tropical Pacific (Philippine Sea), depth 3300 fathoms.

2. Clathrocanium sphærocephalum, n. sp. (Pl. 64, fig. 1).

Cephalis spherical, with regular circular pores and a prismatic horn of the same length, with three serrated edges. Length of the two joints = 2 : 3, breadth 2 : 4. Thorax with three broad, triangular, latticed, divergent ribs, which are separated by three large ovate holes (about as large as the cephalis), and connected at the distal end by a broad fenestrated circular ring of regular lattice-work (about six pores in its height). Peristome smooth, constricted, half as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.08 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. Clathrocanium coarctatum, Ehrenberg.

Clathrocanium coarctatum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf vii. fig. 6. Lychnocanium fenestratum, Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 767.

Cephalis spherical, thorny, with regular circular pores and a simple pyramidal horn of the same length. Length of the two joints = 2 : 3, breadth = 2 : 5. Thorax with three simple, prismatic, little prominent ribs, which are separated by three large ovate holes (twice as long as the cephalis), and connected below the prominent distal end by a narrow circular ring of delicate lattice-work. Peristome smooth, wide, little narrower than the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.06 long, 0.1 broad.

Habitat.—Western Tropical Pacific (Philippine Sea), depth 3300 fathoms.

4. Clathrocanium triomma, n. sp. (Pl. 64, fig. 3).

Cephalis spherical, thorny, with regular circular pores, and a slender prismatic horn of twice the length, bearing at its apex three short recurved branches. Length of the two joints = 2 : 4, breadth = 2 : 5. Thorax with three broad prismatic, fenestrated ribs, which are separated by three large subcircular holes, and below the prominent distal end by a broad, triangular, roundish ring of subregular lattice-work (with square pores). Peristome smooth, about half as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.08 long, 0.1 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Subgenus 2. Clathrocorona, Haeckel, 1881, Prodromus, p. 431.

Definition.—Horn of the cephalis fenestrated. Peristome on the margin of the basal mouth with a corona of spines.

5. Clathrocanium diadema, n. sp. (Pl. 64, fig. 2).

Clathrocorona diadema, Haeckel, 1881, Prodromus, p. 431.

Cephalis hemispherical, thorny, with irregular roundish pores, and a large prismatic horn of twice the length, the three edges of which are denticulate and fenestrated, each with a series of square pores. Length of the two joints = 1 : 3, breadth = 2 : 4. Thorax thorny, with three broad fenestrated divergent ribs, which are separated by three large ovate holes (twice as long as the cephalis) and have their prominent distal ends connected below by a broad circular ring of lattice-work (with irregular polygonal small meshes). Peristome wide, two-thirds as broad as the thorax, with a circular corona of small square pores and alternating prominent small teeth.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.07 long, 0.09 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

6. Clathrocanium reginæ, n. sp. (Pl. 64, fig. 4).

Clathrocorona reginæ, Haeckel, 1881, Prodromus, p. 431.

Cephalis hemispherical, with irregular roundish pores and a prismatic club-shaped horn of twice the length, the three edges of which are denticulate and fenestrated. Length of the two joints = 1 : 3, breadth = 1 : 4. Thorax thorny, with three broad triangular, fenestrated and nodulated ribs, which are separated by three large ovate holes (twice as long as the cephalis) and have their prominent distal ends connected below by a circular ring of lattice-work. Peristome constricted, as broad as the thorax, with a corona of short spines.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.08 long, 0.12 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 541. Lamprodiscus,^[46] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 831.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three divergent lateral ribs in the wall of the flat, conical, discoidal, or pyramidal thorax. Cephalis with a horn. Peristome smooth, without corona of spines.

The genus Lamprodiscus, and the following nearly allied Lampromitra, differ from all preceding Sethopilida in the complete connection of the three thoracic feet by lattice-work, so that they are imbedded in the thorax-wall as prominent ribs and are not prolonged beyond the margin as free feet. The shell is commonly very flat, conical or pyramidal, sometimes nearly discoidal. The margin of Lamprodiscus is simple, smooth.

1. Lamprodiscus monoceros, Ehrenberg.

Lamprodiscus monoceros, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 295, Taf. vii. fig. 2.

Shell smooth, with deep collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 8. Cephalis spherical, hyaline, without pores, with an oblique conical horn of the same length. Thorax flat, campanulate, nearly hemispherical, with convex lateral outlines, and regular hexagonal meshes, increasing gradually in size towards the mouth. Bars very thin. Peristome smooth.

Dimensions.—Cephalis 0.02 diameter; thorax 0.1 long, 0.16 broad.

Habitat.—Western Tropical Pacific (Philippine Sea), Station 200, surface.

2. Lamprodiscus coscinodiscus, Ehrenberg.

Lamprodiscus coscinodiscus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 295, Taf. vii. fig. 3.

Shell smooth, with sharp collar stricture. Thorax of the same form and structure as in the preceding species, differing from it mainly in the structure of the smooth circular margin, which is composed of a ring of very small square pores. Length of the two joints = 1 : 4, breadth = 1 : 8. Cephalis with small hexagonal pores, without horn or with a short rudimentary horn. Lateral outlines of the campanulate thorax in the upper part concave, in the lower convex.

Dimensions.—Cephalis 0.02 diameter; thorax 0.08 long, 0.16 broad.

Habitat.—Tropical Pacific, Stations 206, 224, 266, &c., surface.

3. Lamprodiscus tricostatus, n. sp.

Shell smooth with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 7. Cephalis spherical, with an oblique conical horn of twice the length and small circular pores. Thorax flatly conical, twice as broad as high, with straight lateral outline, and regular hexagonal meshes, increasing gradually in size towards the mouth; bars very thin. Peristome or margin of the basal mouth circular, smooth. Very similar to Theopilium tricostatum (Pl. 70, fig. 6), but without abdomen. Differs from the two preceding species mainly in the conical form of the thorax and the less delicate network.

Dimensions.—Cephalis 0.03 diameter; thorax 0.1 long, 0.2 broad.

Habitat.—Cosmopolitan, Mediterranean, Atlantic, Indian, Pacific; surface.

4. Lamprodiscus lævis, Haeckel.

Eucecryphalus lævis, R. Hertwig, 1879, Organism. d. Radiol., p. 77, Taf. viii. figs. 6, 6a, 6b.

Shell smooth, with distinct collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 6. Cephalis subspherical, with small circular pores and an oblique conical horn of twice the length. Thorax flat, pyramidal, twice as broad as long, with three strong, straight divergent edges and subregular roundish pores. Peristome smooth.

Dimensions.—Cephalis 0.025 diameter; thorax 0.08 long, 0.16 broad.

Habitat.—Mediterranean (Messina), R. Hertwig, surface.

Genus 542. Lampromitra, Haeckel,^[47] 1881, Prodromus, p. 431.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three divergent lateral ribs in the wall of the flat conical or pyramidal thorax. Cephalis commonly with a horn. Peristome with a corona of spines.

The genus Lampromitra differs from the preceding and nearly allied Lamprodiscus only in the development of a dentated peristome, or an elegant corona of teeth around the wide open mouth. It bears therefore to the latter the same relation that Clathrocorona does to Clathrocanium.

1. Lampromitra coronata, n. sp. (Pl. 60, fig. 7, 7a).

Shell flat, conical, with slight collar stricture. Length of the two joints = 1 : 2, breadth = 2 : 7. Cephalis hemispherical, with a conical oblique horn of twice the length, and small subregular hexagonal pores. Thorax with larger, subregular, hexagonal meshes, six to eight times as broad as the bars. Peristome or basal margin of the thorax circular, with a marginal ring of smaller polygonal meshes and a triple coronal of short spines; two external rings of short conical centrifugal spines, and an internal ring of thin centripetal rods (fig. 7a). In fig. 7 the shell is seen from below and exhibits very distinctly the internal cross of the collar septum, composed of the four divergent cortinar bars; between the latter descend the four pear-shaped lobes of the central capsule (each containing an oil globule), whilst the apical part of the capsule (with the nucleus) is hidden in the large cap-shaped cephalis.

Dimensions.—Cephalis 0.03 long, 0.07 broad; thorax 0.06 long, 0.2 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Lampromitra quadricuspis (Pl. 58, fig. 7).

Shell flat, conical, with sharp collar stricture. Length of the two joints = 1 : 3, breadth = 2 : 10. Cephalis hemispherical, with subregular circular pores and an oblique, conical, occipital horn of twice the length, bearing three divergent lateral branches, which are directed upwards, and correspond to the three thoracic ribs. Further down, near the collar stricture, a short divergent frontal horn arises. Thorax with irregular roundish pores of different sizes, three to six times as broad as the bars. Peristome with a simple coronal of short, conical, divergent spines, about as long as the diameter of the cephalis.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.06 long, 0.2 broad.

Habitat.—North Atlantic, Canary Islands, surface.

3. Lampromitra furcata, n. sp. (Pl. 58, fig. 8).

Shell flat, conical, with deep collar stricture, very similar in form and structure to the preceding species; differs from it in the shape of the peristome and the armature of the cephalis, which bears a conical, forked, occipital horn of the same length, and a small rudimentary divergent frontal horn. Length of the two joints = 1 : 2, breadth = 1 : 6. The four pores of the collar septum (two larger cardinal and two smaller jugular) exhibit in this species a peculiar asymmetry (fig. 8). The peristome bears a simple coronal of spines as long as the diameter of the cephalis. The major part of them is forked, some irregularly branched.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.18 broad.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

4. Lampromitra pyramidalis, n. sp.

Shell flat, pyramidal, smooth, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 9. Cephalis subspherical, with an oblique pyramidal horn of twice the length, and small circular pores. Thorax with three strong, divergent, straight ribs and three flat triangular sides between them, with subregular hexagonal pores, increasing in size towards the mouth. Peristome with a simple coronal of large and numerous divergent, conical spines, half as long as the shell.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.09 long, 0.18 broad.

Habitat.—South Atlantic, Station 325, depth 2650 fathoms.

5. Lampromitra huxleyi, Haeckel (Pl. 59, fig. 1).

Eucecryphalus huxleyi, Haeckel, 1879, Natürl. Schöpfungsgesch., Edit. vii. Taf. xvi. fig. 9.

Shell flat, conical, spiny, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 8. Cephalis hemispherical, with a short conical horn of the same length. Thorax with irregular polygonal pores. Peristome with three coronals of divergent bristle-shaped spines; the first directed obliquely upwards, the second outwards, and the third nearly vertically, downwards; the bristles of the latter are much longer, about as long as the height of the shell.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.16 broad.

Habitat.—Australia (east coast), Station 169, surface.

6. Lampromitra schultzei, Haeckel.

Eucecryphalus schultzei, Haeckel, 1862, Monogr. d. Radiol., p. 309, Taf. v. figs. 16-19.

Shell flat, conical, smooth, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 8. Cephalis hemispherical, with a small conical horn of half the length, and very small roundish pores. Thorax with three strong, straight ribs and irregular polygonal pores, which are much larger in the middle part than in the upper or lower part. Peristome with a double coronal of short, conical, divergent spines; the superior obliquely ascending, the inferior vertically descending. (Named in honour of the late Professor Max Schultze, the illustrious histologist.)

Dimensions.—Cephalis 0.025 diameter; thorax 0.07 long, 0.2 broad.

Habitat.—Mediterranean, Messina, surface.

7. Lampromitra arborescens, n. sp, (Pl. 60, fig. 8, 8a).

Shell flat, pyramidal, spiny, with sharp collar stricture. Length of the two joints = 1 : 3, breadth = 2 : 10. Cephalis cap-shaped, with an oblique, slender, conical horn of twice the length, and small circular pores. Thorax with three slight almost obliterated ribs and three vaulted sides between them, with irregular roundish pores. The three ribs are distinct in the proximal, not in the distal part. Peristome with a double coronal of smaller squarish pores and numerous divergent spines; the larger spines are irregularly branched and as long as the diameter of the cephalis.

Dimensions.—Cephalis 0.15 long, 0.03 broad; thorax 0.04 long, 0.2 broad.

Habitat.—Indian Ocean, Madagascar (Rabbe), surface.

8. Lampromitra dendrocorona, n. sp. (Pl. 58, fig. 9).

Shell flat, conical, with smooth surface and deep collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 10. Cephalis hemispherical, with a slender occipital horn of three times the length, and a small divergent frontal horn. Thorax with three strong prominent straight ribs and irregular polygonal meshes, increasing in size towards the mouth. Peristome with a dense coronal of numerous short conical spines and twenty-four to thirty larger arborescent spines, longer than the diameter of the cephalis.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Genus 543. Callimitra,^[48] Haeckel, Prodromus, 1881, p. 431.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three vertical latticed wings, which stretch between the three divergent lateral ribs of the thorax and the vertical horn of the cephalis. No frontal horn.

The genus Callimitra, and the two following nearly allied genera, Clathromitra and Clathrocorys, form together a peculiar small group, the Callimitrida, living in the Central Pacific, and differing from the other Sethopilida in some remarkable points, derived perhaps directly from the Archiscenida, Archiscenium and Pteroscenium, by the development of thoracic network between the three cortinar feet. In the centre of the collar septum, where these feet are united, there arises a vertical free columella, prolonged over the top of the cephalis as a free horn, and this horn is connected with the three thoracic ribs by three vertical fenestrated wings.

1. Callimitra carolotæ, n. sp. (Pl. 63, figs. 1, 7, 8).

Cephalis campanulate, conical, with irregular, polygonal pores, and a thin bristle-shaped apical horn of the same length. Length of the two joints = 3 : 6, breadth = 2 : 6. Thorax in the upper half with irregular network, in the lower half with parallel transverse bars; in each of its three sides descend two convergent pairs of stronger, parallel, curved ribs, not confluent at the peristome. Each of the three vertical wings with eight stronger ribs, three arising from the cephalis, five from each foot. Dedicated to my dear mother Charlotte Sethe.

Dimensions.—Cephalis 0.07 long, 0.05 broad; thorax 0.15 long, 0.15 broad.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

2. Callimitra annæ, n. sp. (Pl. 63, fig. 2).

Cephalis campanulate, conical, with irregular, polygonal pores, and a thin bristle-shaped horn of the same length. Length of the two joints = 1 : 2, breadth = 1 : 3. Thorax nearly in its whole extent with parallel transverse bars, which are crossed by two convergent systems of parallel beams; in each of its three sides descend four convergent pairs of stronger, parallel, curved ribs, not confluent at the peristome. Each of the three vertical wings with six stronger ribs, three arising from the cephalis, three from each foot. Dedicated to my dear first wife Anna Sethe.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.12 long, 0.18 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

3. Callimitra agnesæ, n. sp. (Pl. 63, fig. 5).

Cephalis pear-shaped, with irregular, square pores, and a slender bristle-shaped horn twice as long. Length of the two joints = 1 : 3, breadth = 1 : 5. Thorax in its whole extent with parallel transverse bars, which are crossed by two converging and crossed systems of parallel beams; in each of its three sides descend five convergent pairs of stronger, parallel, curved ribs, the two or three upper of which are crossed at the peristome. Each of the three vertical wings with five stronger ribs, three arising from the cephalis and the horn, two from each foot. Dedicated to my dear second wife Agnes Huschke.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.15 long, 0.22 broad.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

4. Callimitra elisabethæ, n. sp. (Pl. 63, fig. 6).

Cephalis nearly hemispherical, with irregular square pores, and a strong prismatic horn thrice the length. Length of the two joints = 2 : 7, breadth = 2 : 9. Thorax in the upper third with irregular network, in the lower two-thirds with parallel transverse bars which are crossed by two convergent systems of parallel beams; in each of its three sides descend three convergent pairs of stronger, parallel, curved ribs; the two ribs of the uppermost pair are united and confluent in a single odd rib in the lower half of the thorax. Each of the three vertical wings with seven stronger ribs, three arising from the cephalis and the horn, four from each foot. Dedicated to my dear elder daughter Elizabeth Haeckel.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.15 long, 0.2 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

5. Callimitra emmæ, n. sp. (Pl. 63, figs. 3, 4).

Cephalis campanulate, with irregular, polygonal pores, and very thin bars (of the same shape as in the thorax) and with a thin bristle-shaped horn twice the length. Length of the three joints = 3 : 6, breadth = 2 : 9. Thorax in its whole extent with an arachnoidal network similar to that in the cephalis and the three wings, composed of very numerous parallel threads, which are crossed by two crossed diagonal systems of parallel threads. In each of the three sides of the thorax descend five convergent pairs of stronger ribs, the three upper of which are crossed and form large rhomboidal meshes. Each of the three vertical wings with ten stronger ribs, four arising from the cephalis and each horn, six from each foot. Dedicated to my dear younger daughter Emma Haeckel.

Dimensions.—Cephalis 0.07 long, 0.06 broad; thorax 0.15 long, 0.22 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 544. Clathromitra,^[49] Haeckel, 1881, Prodromus, p. 432.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three vertical latticed wings, which stretch between the three divergent lateral ribs of the thorax and the vertical horn of the cephalis. The front of the latter is armed with a large frontal horn.

The genus Clathromitra differs from the preceding similar Callimitra in the development of a free frontal or sternal horn, a prolongation of an internal obliquely ascending rod, opposite to the caudal foot. Therefore the shell in this genus possesses five divergent free spines, two cephalic horns, and three thoracic feet. The lattice-work of the three vertical wings is not so delicate as in Callimitra.

1. Clathromitra pterophormis, n. sp. (Pl. 57, fig. 8).

Cephalis very large, hemispherical, about as long and half as broad as the three-sided pyramidal thorax; both with irregular, polygonal meshes. Apical horn three to four times as long as the frontal horn and the three basal feet. All five spines three-sided prismatic, with nearly smooth edges. Three lateral wings half as broad as the cephalis.

Dimensions.—Cephalis 0.05 long, 0.1 broad; thorax 0.05 long, 0.15 broad.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Clathromitra pentacantha, n. sp.

Cephalis large, hemispherical, half as long as the three-sided pyramidal thorax; both with irregular, roundish meshes. Apical horn of about the same length as the frontal horn, and twice as long as the three basal feet. All five spines three-sided prismatic, with denticulated edges. Three lateral wings about as broad as the cephalis.

Dimensions.—Cephalis 0.04 long, 0.08 broad; thorax 0.1 long, 0.2 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 545. Clathrocorys,^[50] Haeckel, 1881, Prodromus, p. 432.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three prominent lateral ribs on the thorax, alternating with three large holes (or thoracic gates). The three ribs are connected with the central apical horn of the cephalis by three vertical latticed wings.

The genus Clathrocorys differs from the two preceding nearly allied genera in the incomplete fenestration of the thorax, the three perradial ribs of which are separated by three large interradial holes. It has therefore the same relation to Callimitra that Clathrocanium bears to Dictyophimus.

1. Clathrocorys murrayi, n. sp. (Pl. 64, fig. 8).

Cephalis pear-shaped, with irregularly square pores. From the centre of its base there arise four strong, prismatic, radial beams of nearly equal size, the vertical, straight, cephalic horn being little longer than the three divergent, somewhat curved feet. In the three meridional planes (between the horn and each foot) a few rather thick branches arise, which by communication of the ramules form the three vertical latticed wings; each wing with two large meshes, three to five meshes of medium size, and three to four parallel arachnoidal rows of small, square, distal meshes. The three walls of the flat pyramidal thorax (between every two feet) are formed in the upper part by squarish network similar to that of the cephalis, in the middle part by a single row of arches separated by thin threads, and in the lower part by a narrow band of arachnoidal network. Dedicated to Dr. John Murray.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.04 long, 0.15 broad; apical distance of every two feet 0.15, of each foot and the horn 0.17.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Clathrocorys teuscheri, n. sp. (Pl. 64, fig. 10).

Cephalis pear-shaped, with irregular, square pores. From the centre of its base there arise seven prismatic, radial beams of equal strength, supporting the lattice-work of the wall; the single vertical beam is prolonged into the apical horn; six others lie in the three meridian planes (between the horn and each foot); three ascending end in the wall of the cephalis, three descending are prolonged into the three strong feet, which are longer than the horn. In each meridional plane there arise four thicker and several thinner bars, which by communication of their ramules form the three latticed wings; each wing with a single very large mesh, two meshes of medium size, and a narrow marginal band of small, square pores. The three walls of the flat pyramidal thorax are formed in the upper part by squarish network similar to that of the cephalis, in the lower part by a narrow band of the same; between them a large hole. Dedicated to Dr. Reinhold Teuscher.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.15 broad; apical distance of every two feet 0.2, of each foot and the horn 0.2.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Clathrocorys giltschii, n. sp. (Pl. 64, fig. 9).

Cephalis pear-shaped, with irregular, polygonal pores. From the centre of its base there arise seven prismatic, radial beams of different strength; the single vertical beam bears six lateral branches (parallel to the three ascending supporting beams), and is prolonged into the apical horn; six others lie in the three meridional planes (between the horn and each foot); three weaker ascending beams end in the wall of the cephalis, three stronger descending are prolonged into the three large diverging feet, which are twice as long as the cephalic horn. The network of the three wings and of the three-sided pyramidal thorax is about the same as in the preceding species, but much more developed; the marginal bands with the squarish network are much broader, and an arachnoidal wicker-work of very thin thread-like bars fills out the large meshes. Dedicated to Mr. Adolf Giltsch.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.12 long, 0.2 broad; apical distance of every two feet 0.24, of each foot and the horn 0.2.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 546. Eucecryphalus,^[51] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 836.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three free collar wings or solid spines arising from the collar stricture, and freely prominent between the horned cephalis and the flat conical thorax.

The genus Eucecryphalus, according to the restricted definition here given, comprises only those Sethopilida in which the three primary cortinar beams are perfectly free divergent collar wings, i.e., free spines arising outside the shell from the collar stricture, between the cephalis and thorax. The type of this genus (which I formerly united with other Sethopilida) remains Eucecryphalus gegenbauri.

Subgenus 1. Eucyrtomphalus, Haeckel, 1881, Prodromus, p. 431.

Definition.—Peristome or margin of the basal mouth of the thorax smooth, without marginal spines.

1. Eucecryphalus corocalyptra, n. sp.

Shell flatly conical, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 6. Cephalis subspherical, with an oblique conical horn twice its length. Thorax conical, twice as broad as long, with regular hexagonal meshes and straight lateral outlines. From the collar stricture there arise three slender conical spines, about as long as the thorax, divergent downwards. Similar to Corocalyptra agnesæ (Pl. 59, fig. 3), but without lumbar stricture and abdomen. Peristome or basal margin of the mouth of the thorax smooth, simple.

Dimensions.—Cephalis 0.3 diameter; thorax 0.09 long, 0.18 broad.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, surface.

2. Eucecryphalus halicalyptra, n. sp.

Shell flat, campanulate, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 10. Cephalis hemispherical, with two divergent conical horns, a major occipital and a minor frontal horn. Thorax with subregular hexagonal meshes and concave-convex lateral outlines, campanulate. From the collar stricture there arise three divergent bristle-shaped spines, nearly horizontal, about half as long as the thorax. Peristome smooth, with a marginal coronal of small square pores.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.08 long, 0.2 broad.

Habitat.—Central Pacific, Stations 266 to 274, surface.

Subgenus 2. Eucecryphalium, Haeckel.

Definition.—Peristome or margin of the basal mouth of the thorax dentate, with a coronal of marginal spines.

3. Eucecryphalus cuvieri, n. sp.

Shell flatly conical, with slight collar stricture. Length of the two joints = 1 : 8, breadth = 2 : 10. Cephalis hemispherical, with an oblique pyramidal horn twice as long. Thorax with straight outlines and regular hexagonal meshes, increasing in size towards the mouth. From the collar stricture there arise three stout conical spines, half as long as the thorax, and diverging downwards. Peristome with a ring of small square pores and alternate conical divergent spines. Differs from the similar Clathrocyclas alcmenæ (Pl. 59, fig. 6), mainly in the simple apical horn and the possession of the three collar fundamental spines.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.15 long, 0.2 broad.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms.

4. Eucecryphalus mülleri, n. sp.

Shell flatly campanulate, of nearly the same structure as and similar form to that of the preceding species. Differs from it mainly in the considerable size of the cephalic horn and the three collar spines, which are bristle-shaped and longer than the shell. Length of the two joints = 1 : 4, breadth = 2 : 8. The peristome bears a double marginal ring of divergent conical spines, the upper being directed upwards, the lower downwards.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.08 long, 0.16 broad.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

5. Eucecryphalus gegenbauri, Haeckel.

Eucecryphalus gegenbauri, Haeckel, 1862, Monogr. d. Radiol., p. 308, Taf. v. figs. 12-15. Eucecryphalus gegenbauri, R. Hertwig, 1879, Organism. d. Radiol., p. 76, Taf. viii. figs. 5, 5a, 5b.

Shell flatly conical, campanulate, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 8. Cephalis hemispherical, with a conical horn of the same length, and very small pores. Thorax about twice as broad as high, with large, subregular, hexagonal meshes, increasing in size downwards. In the upper half of the thorax the meshes are filled up by an extremely delicate arachnoidal network. From the collar stricture there arise three divergent bristle-shaped spines half as long as the thorax. Peristome with a double coronal of small square pores (the inner smaller and more numerous than the outer), and with a single coronal of divergent marginal spines. This cosmopolitan species is rather variable.

Dimensions.—Cephalis 0.02 to 0.03 diameter; thorax 0.1 to 0.12 long, 0.02 to 0.25 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, surface.

6. Eucecryphalus campanella, Haeckel.

Pterocodon campanella, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xix. fig. 2.

Shell campanulate, conical, with sharp collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 2. Cephalis hemispherical, with a short conical horn half as long, and very small pores. Thorax campanulate, as broad as high, with large roundish meshes, increasing in size downwards. From the collar stricture arise three strong, divergent, somewhat curved spines, nearly as long as the thorax. Peristome with a coronal of ten to twelve strong, conical, marginal spines, which are nearly parallel, directed downwards, a little curved, and half as long as the thorax. In the complete specimen examined by me, the apical horn, the three lateral wings and twelve terminal feet were well preserved.

Dimensions.—Cephalis 0.02 to 0.03 diameter; thorax 0.06 to 0.07 long and broad.

Habitat.—Fossil in Barbados.

Genus 547. Amphiplecta,^[52] Haeckel, 1881, Prodromus, p. 424.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta) with three internal thoracic ribs, enveloped by the network of the thorax. Cephalis with a large apical opening, surrounded by a coronal of spines.

The genus Amphiplecta (or Amphicryphalus) comprises some very peculiar forms of Sethopilida, probably widely remote from the other genera of this subfamily, and derived directly from the Plectanida (compare above, p. 921). The cortinar tripodium, composed of three feet divergent downwards, and one apical horn ascending upwards (in some species also a second frontal horn) is here enclosed in the cavity of a two-jointed shell, which exhibits two large openings, a smaller apical hole in the top of the cephalis, and a larger terminal mouth on the thorax. There is no trace of a sagittal ring.

1. Amphiplecta amphistoma, n. sp.

Cephalis subspherical, spiny, with sharp collar stricture on the base; its apical opening central, surrounded by a coronal of twelve to eighteen short spines. Length of the two joints = 7 : 8, breadth = 6 : 20. Thorax flatly conical, armed with bristle-shaped spines. Meshes of the network in both joints subregular, hexagonal, six to eight times as broad as the bars. Basal mouth bristly.

Dimensions.—Cephalis 0.07 long, 0.06 broad; thorax 0.08 long, 0.2 broad.

Habitat.—Central Pacific, Station 274, surface.

2. Amphiplecta acrostoma, n. sp. (Pl. 97, fig. 10).

Cephalis subspherical, spiny, with distinct collar stricture on the base, its apical opening central, surrounded by a coronal of six to nine divergent denticulate spines. Length of the two joints = 5 : 6, breadth = 4 : 15. Thorax flatly conical, armed with denticulate spines. Meshes of both joints irregular, polygonal, twice to six times as broad as the bars. Basal mouth armed with longer, divergent, denticulate spines.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.15 broad.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

3. Amphiplecta callistoma, n. sp. (Pl. 59, fig. 2).

Cephalis flat, cap-shaped, spiny, with obliterated collar stricture on the base; its apical opening excentric, oblique, surrounded by a coronal of ten to twenty bristle-shaped spines. Length of the two joints = 4 : 5, breadth = 7 : 25. Thorax flatly conical, armed with long bristle-shaped spines. Meshes of both joints irregular, hexagonal, twice to six times as broad as the bars. Basal mouth with a double irregular coronal of small square pores, and of bristle-shaped divergent spines.

Dimensions.—Cephalis 0.04 long, 0.07 broad; thorax 0.05 long, 0.25 broad.

Habitat.—Central Pacific, Station 271, surface.

Genus 548. Lychnocanium,^[53] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta), with three solid terminal feet on the peristome. No thoracic ribs. Cephalis with a horn.

The genus Lychnocanium, very rich in common living and fossil forms, comprises those Sethopilida in which the thorax bears three simple terminal feet around the mouth, but no lateral ribs in its wall. It has therefore been probably derived from Dictyophimus by reduction and loss of these three lateral ribs. The mouth is commonly more or less constricted. The three feet surrounding it are sometimes divergent, straight or curved, at other times parallel and vertical, straight, or curved and convergent. The central capsule exhibited in some living species three or four distinct lobes, filling up the upper half of the thorax.

Subgenus 1. Lychnocanella, Haeckel.

Definition.—Feet divergent, straight or scarcely curved; their terminal distance greater than their basal distance.

1. Lychnocanium lanterna, n. sp. (Pl. 61, fig. 7).

Shell conical, rough, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis with a stout pyramidal horn of the same length. Thorax pear-shaped, twice as broad as the constricted mouth, with regular, circular pores of the same breadth as the bars. Three feet pyramidal, little divergent, straight, about as long as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Central Pacific, Stations 263 to 268, depth 2650 to 2900 fathoms.

2. Lychnocanium continuum, Ehrenberg.

Lychnocanium continuum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. vii. fig. 11.

Shell smooth, with distinct collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis subspherical with a conical horn of the same length. Thorax pear-shaped, twice as broad as the constricted mouth, nearly hyaline, with a very small number of scattered minute pores. Three feet pyramidal, little divergent, straight, about as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.06 broad.

Habitat.—Fossil in Barbados.

3. Lychnocanium pyriforme, n. sp. (Pl. 61, fig. 11).

Shell pear-shaped, rough, with sharp collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 5. Cephalis hemispherical, with a conical horn of the same length. Thorax inflated, four times as broad as the constricted tubular mouth, with regular, circular pores. Three feet pyramidal, straight, divergent, about as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.12 long, 0.15 broad.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, many Stations; also fossil in Barbados.

4. Lychnocanium favosum, n. sp. (Pl. 61, fig. 6).

Shell campanulate, rough, with slight collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 6. Cephalis hemispherical, with a rudimentary pyramidal horn of half the length. Thorax subglobular, three times as broad as the constricted mouth, with regular, circular pores, and an elevated hexagonal framework between them. Three feet cylindrical, slender, straight, divergent, twice to three times as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.025 broad; thorax 0.1 long, 0.12 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

5. Lychnocanium nodosum, n. sp. (Pl. 61, fig. 14).

Shell campanulate, nodose, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subglobular, with a rudimentary conical horn of half the length. Thorax nearly hemispherical, twice as broad as the flat mouth, with regular, circular pores, and a variable number of scattered, conical, fenestrated protuberances. Three feet very large, prismatic, straight, divergent, twice as long as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.12 broad.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

6. Lychnocanium carinatum, Ehrenberg.

Lychnocanium carinatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 5.

Shell campanulate, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis subglobular, with a slender horn of the same length. Thorax conical, twice as broad as the flat mouth, with fifteen to twenty prominent, longitudinal, divergent ribs, alternating with the same number of rows of pores. Three feet slender, prismatic, straight, divergent, twice as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.06 broad.

Habitat.—Fossil in Barbados.

7. Lychnocanium ventricosum, Ehrenberg.

Lychnocanium ventricosum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 12.

Shell pear-shaped, rough, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subglobular, with a stout conical horn twice the length. Thorax conical, three times as broad as the constricted mouth, with irregular, roundish pores of different sizes. Three feet stout, conical, divergent, half as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.07 long, 0.09 broad.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; fossil in Barbados.

8. Lychnocanium tribulus, Ehrenberg.

Lychnocanium tribulus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 1.

Shell pear-shaped, nodose, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 4. Cephalis subglobular, with a conical horn twice the length. Thorax ovate, twice as broad as the constricted mouth, with irregular, roundish pores of different sizes. Three stout feet strongly divergent, pyramidal, about as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.02 broad; 0.08 long, 0.08 broad.

Habitat.—Fossil in Barbados.

Subgenus 2. Lychnocanissa, Haeckel.

Definition.—Feet divergent, more or less curved; their terminal distance greater than their basal distance.

9. Lychnocanium fortipes, n. sp. (Pl. 61, fig. 12).

Shell inflated, rough, with distinct collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 6. Cephalis small, hemispherical, with a pyramidal horn of half the length. Thorax subglobular, truncate, twice as broad as the constricted mouth, with large, regular, circular pores and very thin bars. Three feet very stout, prismatic, twice as long as the thorax, widely divergent, curved with convexity outwards, club-shaped at the distal end, with denticulate edges.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.1 long, 0.12 broad.

Habitat.—Equatorial Atlantic, Station 347, depth 2250 fathoms.

10. Lychnocanium falciferum, Ehrenberg.

Lychnocanium falciferum, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 7; Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 4. Lithomelissa falcifera, Haeckel, 1862, Monogr. d. Radiol., p. 303.

Shell inflated, rough, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis small, with a conical horn of half the length. Thorax subglobular, truncate, three times as broad as the constricted mouth, with small, regular, circular pores. Three feet widely divergent, twice as long as the thorax, curved like a crescent, with strong convexity outwards.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.06 broad.

Habitat.—Fossil in Barbados.

11. Lychnocanium tuberosum, n. sp. (Pl. 61, fig. 13).

Shell conical, tuberculate, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subglobular, with a conical horn of the same length. Thorax inflated, twice as broad as the flat mouth, with small, irregular, roundish pores and scattered fenestrated tubercles. Three feet very large, angular, three times as long as the thorax, curved like a crescent, with strong convexity outwards.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.12 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

12. Lychnocanium hirundo, Ehrenberg.

Lychnocanium hirundo, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 8.

Lithornithium hirundo, Ehrenberg, 1854, Mikrogeol., Taf. xix. fig. 53.

Lithocampe hirundo, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 65.

Shell conical, tuberculate, with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis hemispherical, with a conical horn of half the length. Thorax campanulate, twice as broad as the flat mouth, with longitudinal, divergent ribs, alternating with rows of small circular pores. Three feet divergent, striated, gradually lessening from a broad base, twice as long as the thorax, curved like a crescent, with convexity outwards.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.08 broad.

Habitat.—Fossil in Tertiary rocks of Barbados and the Mediterranean (Sicily, Greece).

13. Lychnocanium fenestratum, n. sp. (Pl. 61, fig. 10).

Shell pear-shaped, rough, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 3. Cephalis subglobular, with a very large prismatic horn, which is about as long as the shell, with three denticulate, prominent, wing-like crests, which are pierced by a series of pores. Thorax ovate, three times as broad as the constricted, prominent mouth, with subregular, circular pores. Three feet arising somewhat above the mouth, prismatic, with denticulate edges, about as long as the thorax, divergent, curved, with convexity outwards.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.08 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

14. Lychnocanium sigmopodium, n. sp. (Pl. 61, fig. 15).

? Lychnocanium tetrapodium, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 3.

Shell campanulate, rough with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 3. Cephalis subspherical, with a slender pyramidal horn twice the length. Thorax inflated, conical, with regular circular pores and a wide open mouth of nearly the same breadth. Three feet widely divergent, twice as long as the thorax, angular, S-shaped, or curved with convexity inwards. (Lychnocanium tetrapodium of Ehrenberg is perhaps a variety of this species?).

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.09 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific, many stations at various depths; also fossil in Barbados and Sicily.

15. Lychnocanium trichopus, Ehrenberg.

Lychnocanium trichopus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 5.

Shell conical, smooth, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis subspherical, with a rudimentary conical horn of half the length. Thorax campanulate, with regular, circular pores and wide open mouth of nearly the same breadth. Three feet divergent, very slender, four to five times as long as the thorax, not broader than one pore, S-shaped, or curved with convexity inwards in the distal half.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.07 long, 0.09 broad.

Habitat.—Fossil in Barbados.

Subgenus 3. Lychnocanoma, Haeckel.

Definition.—Feet parallel, vertical, straight, or little curved; divergent in the basal half, often convergent in the distal half; their terminal distance about equal to the basal distance.

16. Lychnocanium tripodium, Ehrenberg.

Lychnocanium tripodium, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 2.

Shell ovate, smooth, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 4. Cephalis subglobular, with a slender conical horn twice the length. Thorax inflated, twice as broad as the constricted mouth, with small, regular, circular pores. Three feet slender, prismatic, twice to three times as long as the thorax, nearly straight and parallel, vertical.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.07 long, 0.07 broad.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; also fossil in Barbados.

17. Lychnocanium cypselus, Ehrenberg.

Lychnocanium cypselus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. vii. fig. 10.

Shell slender, ovate, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 3. Cephalis subspherical, with a conical horn of the same length. Thorax ovate, truncate, three times as broad as the narrow, constricted mouth, with small, regular, circular pores. Three feet slender, somewhat shorter than the thorax, little curved, with convexity outwards, nearly parallel, vertical. (In the specimen figured by Ehrenberg, the third foot was broken off.)

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.08 long, 0.06 broad.

Habitat.—Fossil in Barbados.

18. Lychnocanium ovatum, n. sp.

Shell ovate, rough, without external collar stricture. Length of the two joints = 1 : 6, breadth = 1 : 5. Cephalis conical, with a stout conical horn of the same length. Thorax ovate, four times as broad as the narrow constricted mouth, with small, regular, circular pores, separated by hexagonal frames of twice the breadth. Three feet cylindrical, half as long as the thorax, and three times as long as broad, straight, parallel, vertical.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax, 0.12 long, 0.1 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

19. Lychnocanium crassipes, Ehrenberg.

Lychnocanium crassipes, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. vii. fig. 7.

Shell campanulate, rough, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a thin conical horn of the same length. Thorax semi-ovate, three times as broad as the narrow constricted mouth, with fifteen to twenty divergent, denticulate ribs, alternating with the same number of rows of small, regular, circular pores. Three feet very stout, as long as the thorax, cylindrical, nearly straight and parallel, vertical, at the distal end clavate, spinulate or a little forked.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.06 long, 0.08 broad.

Habitat.—Fossil in Barbados.

20. Lychnocanium clavigerum, n. sp. (Pl. 61, fig. 4).

Shell campanulate, sulcate, with sharp collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 5. Cephalis subglobular, with a spindle-shaped papillate horn twice the length. Thorax nearly spherical, truncate at both poles, three times as broad as the narrow, constricted, somewhat tubular mouth, with fifteen to twenty elevated meridional ribs, alternating with the same number of rows of circular pores. Three feet slender, cylindrical, twice as long as the thorax, in the basal half divergent, in the distal half convergent, club-shaped, with a thickened papillate end.

Dimensions.—Cephalis 0.02 long, 0.025 broad; thorax 0.08 long, 0.01 broad.

Habitat.—Indian Ocean, Madagascar, surface (Rabbe).

21. Lychnocanium pudicum, n. sp. (Pl. 61, fig. 2).

Shell campanulate, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis hemispherical, hyaline (without pores), with a short and thick club-shaped, spinulate horn of the same length. Thorax subglobular, truncate at both poles, twice as broad as the constricted mouth, with small, irregular, roundish pores. Three feet somewhat shorter than the thorax, curved like a crescent, with convexity outwards; their distal ends club-shaped, spinulate, convergent towards the central axis.

Dimensions.—Cephalis 0.02 long, 0.025 broad; thorax 0.06 long, 0.07 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Genus 549. Lychnodictyum,^[54] Haeckel, 1881, Prodromus, p. 432.

Definition.—Sethopilida (vel Dicyrtida triradiata aperta), with three latticed terminal feet on the peristome, without thoracic ribs. Cephalis originally with a horn (sometimes lost).

The genus Lychnodictyum differs from the preceding Lychnocanium only in the fenestration of the three terminal feet, and bears therefore to it the same relation that the ancestral Tripocyrtis does to Dictyophimus.

1. Lychnodictyum challengeri, Haeckel.

Dictyopodium challengeri, Wyville Thomson, 1877, Atlantic, vol. i. p. 234, fig. 52. Dictyophimus (vel Tripocyrtis) challengeri, Haeckel, 1878, Protistenreich, p. 47, fig. 35.

Shell campanulate, smooth, with sharp collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis subspherical, with a large, oblique, pyramidal horn thrice the length. Thorax with three inflated bosoms between the three decurrent ribs, which are prolonged into three vertical, parallel, pyramidal, in the upper half fenestrated feet, as long as the thorax. Pores regular, circular. Mouth constricted, flat, half as broad as the thorax.

Dimensions.—Cephalis 0.03 diameter; thorax 0.08 long, 0.12 broad.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.

2. Lychnodictyum wyvillei, n. sp.

Shell pyramidal, smooth, with obliterated collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 5. Cephalis subspherical, with a large, straight, pyramidal horn of twice the length. Thorax nearly tetrahedral, inflated, with three rounded, decurrent ribs, which are prolonged into three widely divergent, angular, curved feet, about as long as the shell, with pyramidal fenestrated base. Pores regular, circular. Mouth constricted, flat, half as broad as the thorax.

Dimensions.—Cephalis 0.025 diameter; thorax 0.08 long, 0.12 broad.

Habitat.—Central Pacific, Stations 266 to 274, depth 2350 to 2925 fathoms.

3. Lychnodictyum scaphopodium, n. sp. (Pl. 56, fig. 4).

Cephalis hemispherical, large, without horn, with irregular, small, roundish pores. Thorax a little larger, campanulate, with three broad, shovel-shaped, fenestrated, vertical feet, and larger, irregular pores. In the figured specimen the third (posterior) foot was broken off. In another specimen the three feet were somewhat longer and not so broad.

Dimensions.—Cephalis 0.03 long, 0.05 broad; thorax 0.05 long, 0.06 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

4. Lychnodictyum sethopodium, n. sp.

Cephalis hemispherical, large, with a rudimentary conical horn, and very scarce small pores. Thorax twice as broad and long as the cephalis, campanulate, with irregular, roundish pores, and three slender, pyramidal, divergent feet twice the length, which in the upper half are fenestrated, in the lower half solid.

Dimensions.—Cephalis 0.025 long, 0.045 broad; thorax 0.05 long, 0.09 broad.

Habitat.—South Atlantic, Station 330, surface.

Subfamily 2. Sethoperida, Haeckel, 1881, Prodromus, p. 433.

Definition.—Tripocyrtida with the basal mouth of the shell fenestrated (vel Dicyrtida triradiata clausa).

Genus 550. Sethopera,^[55] Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethoperida (vel Dicyrtida triradiata clausa), with three divergent ribs enclosed in the latticed wall of the thorax. Cephalis with a horn.

The genus Sethopera is probably the oldest form of the Sethoperida, and may therefore be regarded as the common ancestral form of this subfamily. The thorax exhibits three radial ribs, which are completely enclosed in its wall. Sethopera may be derived either from Dictyophimus or from another of the Sethopilida (Lamprodiscus, Clathrocanium) by development of a basal lattice-plate closing the mouth. There are often wide holes or open spaces between the three radial ribs.

1. Sethopera tricostata, n. sp. (Pl. 97, fig. 11).

Cephalis subspherical, spinulate, with a pyramidal horn of the same length. Length of the two joints = 5 : 8, breadth = 5 : 8. Thorax also nearly spherical; in the upper half with three stout, prismatic, convex, divergent ribs, and three large ovate holes between them; in the lower half with numerous small and irregular pores, spinulate.

Dimensions.—Cephalis 0.05 diameter; thorax 0.08 diameter.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Sethopera oceania, Haeckel.

Lithopera oceania, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. iv. fig. 21.

Cephalis hemispherical, with a small bristle-shaped horn of half the length (broken off in Ehrenberg's figure). Length of the two joints = 3 : 4, breadth = 3 : 4. Thorax nearly spherical; in the upper half with three divergent ribs, separated by some larger, irregular pores; in the lower half with numerous small, irregular, roundish pores.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.04 long, 0.04 broad.

Habitat.—North Atlantic, Station 354, surface; Canary Islands and Azores.

3. Sethopera pyrum, Haeckel.

? Lithopera pyrum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297.

Cephalis hemispherical, with a small conical horn of half the length. Length of the two joints = 3 : 10, breadth = 3 : 7. Thorax pear-shaped, with rather large, regular, quincuncial pores; its upper half with three divergent ribs in the wall, half as broad as the subspherical lower half. (The three ribs probably were overlooked by Ehrenberg.)

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.1 long, 0.07 broad.

Habitat.—North Pacific, Station 256, surface; Californian Sea, 2600 fathoms, Ehrenberg.

4. Sethopera lagena, Haeckel.

Lithopera lagena, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 4.

Cephalis pear-shaped, with a small conical horn of half the length. Length of the two joints = 3 : 8, breadth = 3 : 6. Thorax smooth, pear-shaped, with irregular roundish pores; in the wall of its upper third three divergent thin ribs (sometimes wanting); the lower half inflated. (Compare Sethocapsa lagena.)

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.08 long, 0.06 broad.

Habitat.—Fossil in Barbados.

Genus 551. Lithopera,^[56] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Sethoperida (vel Dicyrtida triradiata clausa), with three divergent ribs enclosed in the cavity of the thorax. Cephalis with a horn.

The genus Lithopera is, like the preceding Sethopera, one of the most simple and oldest forms of the Sethoperida, and exhibits three divergent thoracic ribs, which are prolonged neither into lateral wings nor into basal feet. But whilst in Sethopera the three ribs are enclosed in the lattice-work of the shell-wall, in Lithopera they lie freely in its cavity, and are overgrown by the enveloping shell-wall, being inserted on its inner face with their distal ends. Lithopera may be derived directly from Lithomelissa, by development of lattice-work closing the shell-mouth. Therefore the lower part of the cephalis is hidden in the uppermost part of the thorax; only its upper part is free.

1. Lithopera bacca, Ehrenberg.

Lithopera bacca, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. viii. fig. 1.

Cephalis spherical, with small, irregular pores and a bristle-shaped spine of half the length; its lower half hidden in the thorax. Length of the two joints = 1 : 6, breadth = 1 : 5. Thorax ellipsoidal, smooth, with regular, hexagonal, small pores, and very thin, thread-like bars. From the deep collar stricture there arise three internal, divergent bars, which are inserted at the uppermost third of the thorax.

Dimensions.—Cephalis 0.02 diameter; thorax 0.12 long, 0.1 broad.

Habitat.—Tropical Pacific, Stations 200, 224, 266, 271, &c., surface.

2. Lithopera bursella, Ehrenberg.

Lithopera bursella, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. x. fig. 4.

Shell of about the same form and structure as in the nearly allied preceding species, but smaller, of more slender form, with smaller pores and thinner bars. Length of the two joints = 1 : 5, breadth = 1 : 3. In the specimen observed by me the three internal, divergent bars of the ellipsoidal thorax (not seen by Ehrenberg) were as distinct as in the similar preceding and following species.

Dimensions.—Cephalis 0.02 diameter; thorax 0.1 long, 0.06 broad.

Habitat.—Indian Ocean, Zanzibar (Pullen), Madagascar (Rabbe), surface.

3. Lithopera ananassa, n. sp. (Pl. 57, fig. 3).

Shell of about the same form and structure as in the two preceding species, but larger and more robust, and differing in the spiny surface. Length of the two joints = 1 : 5, breadth = 1 : 4. Here also the lower half of the spherical cephalis is submerged in the ellipsoidal thorax, and from the collar stricture arise three strong, internal, divergent beams. The bars of the hexagonal pores are much thicker than in the two preceding species.

Dimensions.—Cephalis 0.03 diameter; thorax 0.16 long, 0.12 broad.

Habitat.—Tropical Atlantic, Stations 347 to 352, surface.

4. Lithopera globosa, n. sp.

Cephalis spherical, very small, with two divergent conical horns of half the length; its lower half hidden in the thorax. Length of the two joints = 1 : 5, breadth = 1 : 5. Thorax spherical, with regular, circular, hexagonally-framed pores. From the collar stricture arise three radial internal beams, horizontally diverging, and inserted at the inside of the thorax.

Dimensions.—Cephalis 0.03 diameter; thorax 0.15 diameter.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

5. Lithopera gutta, Ehrenberg.

Lithopera gutta, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. viii. fig. 2.

Shell pear-shaped, with sharp collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 3. Cephalis spherical, with a conical horn of the same length; its lower half hidden in the uppermost part of the ovate thorax, and connected with its wall by three internal, cortinar beams. Pores of the thorax very irregular in form and size, partly lobed.

Dimensions.—Cephalis 0.02 diameter; thorax 0.08 long, 0.06 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms; Philippine Sea (depth 3300 fathoms), Ehrenberg.

Genus 552. Micromelissa,^[57] Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethoperida (vel Dicyrtida triradiata clausa), with three divergent, solid, lateral wings. Cephalis with a horn.

The genus Micromelissa differs from the two preceding genera in the free prominence of the three cortinar ribs, forming three solid lateral wings. Beyond these the thorax walls are convergent, and the basal mouth closed by a lattice-plate. Therefore Micromelissa may have arisen from Lithomelissa simply by development of this basal mouth-plate.

1. Micromelissa bombus, n. sp. (Pl. 57, fig. 14).

Shell smooth, with sharp collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 5. Cephalis spherical, with an oblique conical horn of the same length. Thorax subspherical, in the upper half with three conical, downwardly diverging wings, about as long as its radius. Pores very small and scarce.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.09 long, 0.1 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Micromelissa vespa, n. sp.

Shell smooth, with deep collar stricture. Length of the two joints = 2 : 5, breadth = 2 : 3. Cephalis spherical, with an oblique pyramidal horn twice the length. Thorax inversely ovate, in the upper half with three pyramidal wings, which are equal to its breadth, little curved and diverging downwards. Pores very small and scarce.

Dimensions.—Cephalis 0.04 diameter; thorax 0.1 long, 0.06 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. Micromelissa apis, n. sp.

Shell rough, with deep collar stricture. Length of the two joints = 2 : 3, breadth = 2 : 4. Cephalis subspherical, with a straight conical horn of half the length, and subregular, circular, double-contoured pores, of the same breadth as the bars. Thorax little larger, subspherical, with irregular, roundish pores, twice to four times as broad as the bars. From its lower half arise three short conical wings, curved downwards, and half as long as the cephalis.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.08 broad.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

4. Micromelissa microptera, Haeckel.

Lithomelissa microptera, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 2; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 78, Taf. iii. fig. 13. Lithomelissa microptera, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxiii. fig. 26.

Shell smooth, with distinct collar stricture. Length of the two joints = 4 : 6, breadth = 3 : 5. Cephalis ovate, with a straight sword-shaped horn of the same length and very small pores, some larger ones above the stricture. Thorax little larger, ovate, nearly hyaline, with very few and small scattered pores. From its uppermost part arise three short conical wings, scarcely half as long as the cephalic horn, little curved and divergent downwards.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.06 long, 0.05 broad.

Habitat.—Fossil in Barbados.

5. Micromelissa ventricosa, Haeckel.

Lithomelissa ventricosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 11.

Shell rough, with slight collar stricture. Length of the two joints = 1 : 7, breadth = 1 : 5. Cephalis small, hemispherical, with a small conical horn of half the length. Thorax ovate, very large, papillate, with irregular, roundish pores. From its basal part arise three short and stout conical wings at great distances, shorter than the cephalis. (A transition-form to Sethocapsa.)

Dimensions.—Cephalis 0.02 long, 0.022 broad; thorax 0.14 long, 0.11 broad.

Habitat.—Fossil in Barbados.

Genus 553. Peromelissa,^[58] Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethoperida (vel Dicyrtida triradiata clausa) with three divergent solid lateral wings. Cephalis without horn.

The genus Peromelissa differs from the preceding ancestral form, Micromelissa, only in the absence of the cephalic horn, which is lost by reduction.

1. Peromelissa phalacra, n. sp. (Pl. 57, fig. 11).

Shell smooth, with two joints of nearly equal size and similar ovate form. Cephalis in the upper half hyaline, without pores; in the lower half with four remote, transverse rows of irregular, roundish pores, decreasing in size towards the hemispherical summit. Thorax with twelve transverse rows of pores, the upper six rows three to four times as large as the lower six rows. From its upper half diverge almost horizontally three angular club-shaped wings, half as long as the shell.

Dimensions.—Cephalis 0.05 long, 0.06 broad; thorax 0.06 long, 0.05 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Peromelissa psilocrana, n. sp.

Shell smooth, very similar to the preceding species in size and form, but differing from it in the disposition of the irregular, roundish pores, which are irregularly scattered, and in the form of the three wings, which are slender, pyramidal, diverging downwards, and about as long as the entire shell.

Dimensions.—Cephalis 0.07 long, 0.06 broad; thorax 0.07 long, 0.06 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Peromelissa capito, Haeckel.

Lithomelissa capito, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 14.

Shell rough, with two joints of nearly equal size and similar ovate form. Pores irregular, roundish, everywhere scattered. From the upper half of the thorax arise three short conical wings, which are little curved and diverge downwards (scarcely half as long as the breadth of the shell).

Dimensions.—Cephalis 0.07 long, 0.06 broad; thorax 0.07 long, 0.06 broad.

Habitat.—Fossil in Barbados.

4. Peromelissa calva, n. sp. (Pl. 57, fig. 12).

Shell rough, with two ovate joints of somewhat different sizes. Pores irregular, roundish, everywhere scattered. Thorax little larger than the cephalis; from its upper half arise three short conical wings, diverging downwardly or nearly horizontally.

Dimensions.—Cephalis 0.06 long, 0.04 broad; thorax 0.07 long, 0.05 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

Genus 554. Sethomelissa,^[59] Haeckel, 1881, Prodromus, p. 431.

Definition.—Sethoperida (vel Dicyrtida triradiata clausa) with three divergent latticed lateral wings. Cephalis with a horn (or a bunch of horns).

The genus Sethomelissa differs from the nearly allied Micromelissa in the fenestration of the three lateral wings, and may be derived either from this genus by development of lattice-work connecting the three wings with the shell, or perhaps from Clathrocanium by closing the mouth.

1. Sethomelissa hymenoptera, n. sp.

Cephalis subspherical, thorny, with a bunch of three divergent, larger apical spines. Thorax pear-shaped, with three broad, triangular, latticed wings, the superior edge of which is a horizontal, straight, and stout spine, nearly as long as the thorax. Pores irregular, roundish.

Dimensions.—Cephalis 0.03 diameter; thorax 0.11 long, 0.08 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 555. Tetrahedrina,^[60] Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethoperida (vel Dicyrtida triradiata clausa) with a three-sided pyramidal thorax, the three edges of which are prolonged into three divergent, solid, terminal feet. Cephalis with a horn.

The genus Tetrahedrina, and the two following nearly allied genera, are distinguished by the possession of three free, divergent, terminal feet, projecting over the latticed mouth of the thorax. Tetrahedrina may be derived directly from Dictyophimus, by development of a horizontal latticed mouth-plate from the middle part of the feet, the lower part of which remains free. This genus, not noticed by Ehrenberg, is similar to his Lithochytris, and common in the Barbados deposits.

1. Tetrahedrina pyramidalis, n. sp.

Shell three-sided pyramidal, smooth, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 4. Cephalis hemispherical, with small, sparsely disposed pores, and a pyramidal horn of the same length. Thorax with subregular, circular pores and three sharp edges, prolonged into three divergent pyramidal feet of the same length.

Dimensions.—Cephalis 0.03 diameter; thorax 0.12 long, 0.12 broad.

Habitat.—Fossil in Barbados.

2. Tetrahedrina pyriformis, n. sp.

Shell pear-shaped, rough, with distinct collar stricture. Length of the two joints = 2 : 6, breadth = 2 : 5. Cephalis subspherical, with a conical horn of the same length. Thorax with subregular, circular pores, ovate, at the broad base with three pyramidal, widely divergent feet of the same length. (Similar to Lychnocanium tribulus, Ehrenberg, 1875, loc. cit., pl. vii. fig. 1, but with the mouth closed by a lattice-plate.)

Dimensions.—Cephalis 0.04 diameter; thorax 0.12 long, 0.1 broad,

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Tetrahedrina quadricornis, Haeckel.

Lithochytris triangula, Bury, 1862, Polycystins of Barbados, pl. xix. figs. 4, 5, 6.

Shell pear-shaped, papillate, with slight collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 5. Cephalis subspherical, with a stout conical horn twice the length. Thorax with irregular, roundish, lobulated pores, with three conical, stout, divergent feet at the base, of the same size and form as the cephalic horn.

Dimensions.—Cephalis 0.02 diameter; thorax 0.1 long, 0.1 broad.

Habitat.—Fossil in Barbados.

Genus 556. Sethochytris,^[61] Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethoperida (vel Dicyrtida triradiata clausa) with three terminal latticed feet or hollow, fenestrated, divergent, basal apophyses of the thorax. Cephalis with a horn.

The genus Sethochytris differs from the preceding Tetrahedrina in the fenestration of the three basal feet, which form direct protrusions or evaginations of the three basal corners of the pyramidal shell. It may be derived from Sethopera by centrifugal growth of the basal corners.

1. Sethochytris triconiscus, n. sp. (Pl. 57, fig. 13).

Shell rough, with deep collar stricture. Length of the two joints = 1 : 8, breadth = 1 : 3. Cephalis spherical, with an oblique pyramidal horn of the same length. Thorax campanulate, conical; its three basal corners prolonged into three divergent, slender, hollow, fenestrated cones, twice as long as the thorax, and ending in a stout pyramidal spine.

Dimensions.—Cephalis 0.04 diameter, thorax 0.12 diameter, length of the feet 0.2.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Sethochytris barbadensis, Haeckel.

Lithochytris barbadensis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 160, Taf. v. fig. 2.

Shell smooth, with slight collar stricture. Length of the two joints = 1 : 6, breadth = 1 : 4. Cephalis ovate, with a conical horn of half the length. Thorax conical; its base prolonged into three divergent, hollow, fenestrated cones, half as long as the thorax. Pores small, subregular, circular.

Dimensions.—Cephalis 0.025 diameter, thorax 0.1 diameter, length of the feet 0.05.

Habitat.—Fossil in Barbados.

3. Sethochytris pyramis, n. sp.

Shell smooth, with slight collar stricture. Length of the two joints = 1 : 8, breadth = 1 : 5. Cephalis ovate, with a conical horn of half the length. Thorax pyramidal, with three sharp edges; its base prolonged into three pyramidal, divergent, hollow, fenestrated feet, nearly as long as the thorax. Pores regular, circular, double-contoured.

Dimensions.—Cephalis 0.04 diameter; thorax 0.2 diameter, length of the feet 0.15.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms; also fossil in Barbados.

4. Sethochytris triangula, Haeckel.

Lithochytris triangula, Bury, 1862, Polycystins of Barbados, pl. xix. fig. 7.

Shell rough, with obliterated collar stricture (but distinct internal collar septum). Length of the two joints = 1 : 6, breadth = 1 : 3. Cephalis subspherical, with a stout conical horn of the same length. Thorax pear-shaped, inflated; its base prolonged into three divergent, hollow, fenestrated cones, about as long as the thorax. Pores regular, circular.

Dimensions.—Cephalis 0.03 diameter; thorax 0.09 diameter, length of the feet 0.1.

Habitat.—Fossil in Barbados.

Genus 557. Clathrolychnus,^[62] Haeckel, 1881, Prodromus, p. 431.

Definition.—Sethoperida (vel Dicyrtida triradiata clausa), with three vertical, lateral latticed wings stretched between the apical horn and the three terminal feet. The external lattice-work connecting the wings and closing the mouth forms an arachnoidal mantle around the shell.

The genus Clathrolychnus may be derived directly from Clathrocorys, by development of an external arachnoidal mantle connecting the three wings and the three feet, and enveloping the whole shell, closing at the same time the basal mouth of the thorax by a fenestrated plate.

1. Clathrolychnus araneosus, n. sp. (Pl. 64, fig. 5).

Cephalis subspherical, with irregular, polygonal pores and a large pyramidal horn of twice the length. Length of the two joints = 4 : 9, breadth = 5 : 12. Thorax with three large triangular holes (twice as broad as the cephalis) between the three pyramidal, divergent feet, which at the distal end are connected by a narrow band of network, composed of two or three rows of polygonal pores. The entire pyramidal shell is enveloped by a very delicate web of irregular, polygonal meshes, closing also the basal mouth. (In fig. 5 the greater part of the web is taken off to demonstrate the large holes of the thorax). Only two feet are visible.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.09 long, 0.12 broad.

Habitat.—Central Pacific, Station 274, surface.

2. Clathrolychnus periplectus, n. sp. (Pl. 64, fig. 6).

Cephalis subspherical, with subregular, circular pores and a pyramidal horn of the same length. Length of the two joints = 1 : 2, breadth = 1 : 3. Thorax with three large elliptical holes between the three pyramidal, divergent feet, which are connected at the distal end by a broad band of network, composed of five to ten rows of polygonal pores. The entire pyramidal shell is enveloped by a very delicate web, which on the sides is composed of subregular, square meshes, and on the closed mouth of polygonal meshes. (In fig. 6 only a part of the web is represented.)

Dimensions.—0.04 long, 0.05 broad; thorax 0.08 long, 0.14 broad.

Habitat..—Central Pacific, Station 271, surface.

Family LXIII. Anthocyrtida, n. fam.

Sethophormida et Sethophænida, Haeckel, 1881, Prodromus, p. 432, 433.

Definition.—Dicyrtida multiradiata. (Cyrtoidea with a two-jointed shell, divided by a transverse constriction into cephalis and thorax, and bearing numerous—four to nine or more—radial apophyses.)

The family Anthocyrtida, composed of the Sethophormida and Sethophænida of my Prodromus, comprises those Cyrtoidea in which the shell is two-jointed and bears numerous radial apophyses. The two subfamilies differ in the shape of the mouth, which in the Sethophormida is a simple, wide opening; in the Sethophænida closed by a lattice-plate.

Numerous fossil and living forms of Anthocyrtida were described formerly by Ehrenberg in his genera Carpocanium and Anthocyrtis. These, however, represent only a small part of the whole family, which exhibits a great variety in the composition of the lattice-work and in the number of radial beams. The number of species here described amounts to one hundred and forty, and these are disposed in fourteen genera (twelve Sethophormida and two Sethophænida).

The Sethophormida may be again divided into two different groups or tribes, the Sethamphorida and Carpocanida; in the former the thorax bears numerous radial ribs, enclosed in its wall; in the latter these ribs have disappeared, and only a corona of terminal feet is developed around the mouth. The shell of the former is usually pyramidal, with a widely open mouth; of the latter ovate, with a constricted mouth. The mouth of the thorax becomes perfectly closed in the Sethophænida.

The majority of the Anthocyrtida may be derived from the Polyspyrida (Petalospyris, &c.) by reduction of the cephalis and loss of the sagittal ring, as was suggested by Bütschli (1882, loc. cit.). But another part may also have arisen from the Tripocyrtida, by interpolation of secondary radial apophyses between the three primary perradial apophyses. The cephalis in this family is developed in all possible degrees, from one of a considerable size to one very much reduced. If it becomes perfectly lost, the Cyrtocalpida arise.

Synopsis of the Genera of Anthocyrtida.

I. Subfamily Sethophormida. Terminal mouth of the thorax a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Radial ribs smooth (rarely thorny) enclosed in the wall of the thorax (cephalis commonly small, without horns).			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell flat, campanulate or nearly discoidal (cephalis without horn),			558. Sethophormis.
						Shell ovate, with constricted mouth (without horn),			559. Sethamphora.
						Shell slender pyramidal, with straight ribs.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Meshes of the network simple,	560. Sethopyramis.
								Meshes fenestrated by secondary latticework,	561. Plectopyramis.
								Meshes closed by spongy framework,	562. Spongopyramis.
		Radial ribs thorny (rarely smooth) prolonged into free terminal feet (cephalis commonly large, with one or more horns).			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Shell not enveloped by arachnoidal network,			563. Acanthocorys.
						Shell enveloped by arachnoidal network,			564. Arachnocorys.
		No ribs in the thorax. Peristome with free terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Cephalis well-developed with an apical horn.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Feet terminal, without separate peristome.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Six feet,	565. Anthocyrtoma.
								Nine feet,	566. Anthocyrtis.
								Twelve or more feet,	567. Anthocyrtium.
						Feet subterminal, outside the constricted peristome,			568. Anthocyrtidium.
				Cephalis rudimentary, hidden in the upper part of the thorax, without horn,					569. Carpocanium.
II. Subfamily Sethophænida. Terminal mouth closed by a lattice-plate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Thorax with lateral apophyses (four to six or more wings),							570. Sethophæna.
		Thorax with terminal apophyses (four to six or more feet),							571. Clistophæna.

Subfamily 1. Sethophormida, Haeckel, 1881, Prodromus, p. 432.

Definition.—Anthocyrtida with the basal mouth of the shell open (vel Dicyrtida multiradiata aperta).

Genus 558. Sethophormis, Haeckel,^[63] 1881, Prodromus, p. 432.

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) with numerous radial ribs in the wall of the flat and broad campanulate or nearly discoidal thorax. Cephalis also flat and broad, cap-shaped without horn.

The genus Sethophormis comprises a great number of widely distributed and large Dicyrtida, all agreeing in the flat cap-shaped or nearly discoidal form of the thorax, which has constantly a very delicate network, and is pierced by numerous radial beams. Four of these are commonly primary and direct prolongations of the four cortinar rods in the collar septum, whilst the others are secondary or interpolated ribs. Sethophormis may be derived either from the triradial Lamprodiscus by multiplication of the ribs (or interpolation of secondary ribs between the three primary), or from Halicalyptra by development of transverse rods connecting its terminal feet, and forming a ribbed thorax. Corresponding to the number of the ribs, we may distinguish as subgenera (separate genera in my Prodromus, 1881, p. 432) Tetraphormis with four, Pentaphormis with five, Hexaphormis with six, Octophormis with eight, Enneaphormis with nine, and Astrophormis with ten to twenty or more ribs. The cephalis bears no horn, and is usually large, flat, cap-shaped or hemispherical.

Subgenus 1. Tetraphormis, Haeckel, 1881, Prodromus, p. 432.

Definition.—Thorax with four radial ribs opposite in pairs in two meridional planes, perpendicular to one another. Collar septum with four large pores.

1. Sethophormis cruciata, n. sp.

Cephalis very large, hemispherical with irregular, delicate network of small square meshes. Thorax flatly campanulate, with delicate, regular network of small hexagonal meshes. All bars very thin, thread-like. Four stout radial thoracic ribs, crossed in pairs, lie in two meridional planes, perpendicular to one another. Very similar to Sethophormis aurelia (Pl. 55, figs. 3, 4), but not so flat, and with only four thoracic ribs. Peristome or margin of the thoracic mouth smooth, circular.

Dimensions.—Cephalis 0.04 long, 0.08 broad; thorax 0.12 long, 0.36 broad.

Habitat.—Central Pacific, Station 271, surface.

2. Sethophormis medusa, n. sp.

Cephalis very large, flat, cap-shaped, with irregular, delicate network of polygonal meshes. Thorax flat, campanulate, nearly hemispherical, with delicate, irregular network of small polygonal meshes. All bars very thin, thread-like. Four stout radial thoracic ribs, as in the preceding species. Peristome denticulate.

Dimensions.—Cephalis 0.03 long, 0.09 broad; thorax 0.15 long, 0.25 broad.

Habitat.—North Pacific, Station 244, surface.

Subgenus 2. Pentaphormis, Haeckel, 1881, Prodromus, p. 432.

Definition.—Thorax with five radial ribs, one of the three primary ribs (the odd occipital rib) being simple, the two others (the paired lateral ribs) forked.

3. Sethophormis pentalactis, n. sp. (Pl. 56, fig. 5).

Cephalis large, flat, hemispherical, with subregular, hexagonal pores. Thorax flat, campanulate, nearly hemispherical; also with subregular, hexagonal pores, and with five stout ribs. The three primary ribs of the thorax are complete, and reach the peristome; the two secondary ribs (as basal branches of the two lateral ribs) are incomplete and absent in the distal half of the thorax. Peristome denticulate, with an elegant marginal corona of small square pores and short conical spines.

Dimensions.—Cephalis 0.03 long, 0.06 broad; thorax 0.1 long, 0.2 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

4. Sethophormis asteriscus, n. sp.

Cephalis large, flat, cap-shaped, with irregular polygonal pores. Thorax flat, campanulate, with subregular, hexagonal pores, and five stout ribs. The marginal distance between the two anterior (lateral) ribs is twice as great as the distance between every two other ribs (the postero-lateral ribs being basal branches of the antero-lateral ribs). Peristome with a double corona of short, conical spines.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.06 long, 0.17 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

5. Sethophormis astrodiscus, n. sp.

Cephalis small, flatly vaulted, cap-shaped with irregular polygonal pores. Thorax very flatly vaulted, nearly discoidal, with subregular hexagonal pores, and five stout ribs. The marginal distance between all five ribs is nearly equal. Peristome denticulate with an elegant corona of small square pores and short conical thorns.

Dimensions.—Cephalis 0.015 long, 0.035 broad; thorax 0.05 long, 0.2 broad.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

Subgenus 3. Hexaphormis, Haeckel, 1881, Prodromus, p. 432.

Definition.—Thorax with six radial ribs (three primary perradial and three secondary interradial beams).

6. Sethophormis hexalactis, n. sp. (Pl. 56, fig. 6).

Cephalis large, hemispherical, with irregular, polygonal pores. Thorax flatly campanulate, with subregular, hexagonal pores, and six stout radial ribs; the lateral connected in pairs. (Fig. 6 exhibits the central part of the shell, seen from below.) In the subcircular collar septum the two anterior (jugular) meshes are much smaller than the two posterior (cardinal) meshes. The odd anterior (sternal) rib is opposite to the posterior (caudal) rib. The two paired ribs of each side (antero-lateral or pectoral and postero-lateral or ventral ribs) diverge from one common point. In the specimen figured the left half of the thorax exhibited the two regular ribs, and the right half three, a posterior accessory branch being developed (transition to Octophormis). This specimen might indeed be called Heptaphormis heptalactis.

Dimensions.—Cephalis 0.02 long, 0.05 broad; thorax 0.08 long, 0.22 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

7. Sethophormis hexagonalis, n. sp.

Cephalis small, flat, cap-shaped, with small, regular, hexagonal pores. Thorax flatly conical, nearly discoidal, with larger pores of the same form, and six stout, straight, prominent ribs. These arise at equal distances from the six corners of the hexagonal base of the collar septum. Peristome hexagonal, with a corona of short spines.

Dimensions.—Cephalis 0.015 long, 0.04 broad; thorax 0.06 long, 0.24 broad.

Habitat.—North Atlantic, Station 354, surface.

Subgenus 4. Octophormis, Haeckel.

Definition.—Thorax with eight radial ribs, four secondary interradial beams being interpolated between the four primary perradial beams of Tetraphormis.

8. Sethophormis octalactis, n. sp.

Cephalis large, hemispherical, with irregular, polygonal pores. Thorax flatly campanulate, with regular, hexagonal pores, and eight stout, regularly-disposed, radial ribs reaching the margin at equal distances. Four of these correspond to the four primary ribs of Tetraphormis cruciata, and exhibit at their base a larger pair of basal pores, surrounded by a semicircular ring (Pl. 70, fig. 5); the other four are secondary, interpolated. Peristome circular, simple.

Dimensions.—Cephalis 0.03 long, 0.06 broad; thorax 0.1 long, 0.22 broad.

Habitat.—Indian Ocean, Madagascar (Rabbe), surface.

Subgenus 5. Enneaphormis, Haeckel, 1881, Prodromus, p. 432.

Definition.—Thorax with nine radial ribs, three of which are the primary beams, the other six being secondary and interpolated.

9. Sethophormis rotula, n. sp. (Pl. 57, fig. 9).

Enneaphormis rotula, Haeckel, 1881, Prodromus et Atlas, pl. lvii. fig. 9.

Cephalis very large, flat, cap-shaped, trilobed, with irregular, polygonal network. Horizontal collar-ring stout, hexagonal, with three larger and three alternate smaller sides of half the length. From the middle of the three larger sides arise three horizontal, centripetal, radial beams, which are united in the centre of the collar-septum—the three primary cortinar beams. These are prolonged outside into three centrifugal primary ribs of the thorax. From the six corners of the collar-ring arise six other secondary, thoracic ribs, equal in size and similar in form to the three primary. Each of these nine equal, straight ribs of the thorax is thickened towards the distal end, and bears at equal distances five pairs of opposite (tangential) lateral branches. The opposite branches of the neighbouring spines become united, and lie nearly horizontally in one plane, so that the flat, discoidal thorax is like a nine-angled wheel with nine equally distant spokes and five concentric, nine-angled rings.

Dimensions.—Cephalis 0.12 diameter, thorax 0.36 diameter.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

10. Sethophormis triloba, n. sp.

Cephalis large, hemispherical, distinctly trilobed, with dense, irregular, polygonal network. From the centre of its top diverge three stout arches or semilunar rods, which are curved downwards, and unite with the three horizontal, radial beams of the collar-septum inside the collar-ring. These three parietal arches of the cephalis are much stronger than in the similar preceding species (Pl. 57, fig. 9), and between them are placed three vaulted bosoms of the cephalis. The collar-ring and the thorax are of the same form as in the preceding, but possess only four concentric, nine-angled rings.

Dimensions.—Cephalis 0.05 long, 0.08 broad; thorax 0.24 diameter.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

11. Sethophormis enneastrum, n. sp.

Cephalis very large, flat, cap-shaped, with hexagonal base, trilobed, of similar form and structure to the two preceding species. The flat, discoidal thorax has also the same form, with nine stout ribs and five concentric, nine-angled rings; its forty-five large meshes, however, are not so simple as these (Pl. 57, fig. 9), but are subdivided into irregular, smaller meshes by interpolated radial beams connecting the concentric rings.

Dimensions.—Cephalis 0.1 diameter, thorax 0.3 diameter.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

12. Sethophormis arachnium, n. sp.

Cephalis very large, flat, cap-shaped, trilobed, with hexagonal base, of the same structure as in the three preceding species. The flat discoidal thorax is also similar, and has the same structure as in the preceding species (Pl. 57, fig. 9); but the number of concentric, nine-angled rings is raised from five to eight, and in its outer part nine secondary radial beams are interpolated between the nine primaries, so that the peristome has not nine but eighteen corners.

Dimensions.—Cephalis 0.08 diameter, thorax 0.4 diameter.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

13. Sethophormis enneactis, n. sp.

Cephalis small, hemispherical, with small, irregular, polygonal pores. Thorax flatly pyramidal, nearly discoidal, with nine prominent, stout ribs, which are connected by numerous (twelve to sixteen) horizontal, nine-angled rings. In the outer half of the thorax there are nine weaker secondary ribs interpolated between the nine stronger primaries, and eighteen shorter and feebler tertiary ribs between the former and the latter. Peristome denticulated, nine-angled.

Dimensions.—Cephalis 0.03 diameter, thorax 0.08 long, 0.24 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

14. Sethophormis eupilium, n. sp. (Pl. 56, fig. 9).

Sethopyramis eupilium, Haeckel, 1882, Atlas, pl. lvi. fig. 9. Craspedilium eupilium, Haeckel, 1878, Manuscript.

Cephalis very small, hemispherical, hyaline, without pores. Thorax flatly pyramidal, with nine concave, triangular faces and nine little curved, stout, radial beams. Between these are interpolated numerous incomplete secondary beams, which are absent in the apical part of the thorax. The radial beams being connected by numerous (thirty to forty or more) horizontal, ring-like threads, a delicate arachnoidal network with small, quadrangular pores is produced. Peristome nine-angled, with a peculiar vertical gallery, composed of four horizontal, parallel, nine-angled rings, which are connected by numerous vertical, parallel bars, therefore with three transverse rows of square pores. This peculiar species is very different from the preceding and may represent a separate genus, Craspedilium.

Dimensions.—Cephalis 0.01 diameter, thorax 0.1 long, 0.25 broad.

Habitat.—Central Pacific, Station 271, surface.

Subgenus 6. Astrophormis, Haeckel.

Definition.—Thorax with a variable number of radial ribs (twelve to twenty or more).

15. Sethophormis aurelia, n. sp. (Pl. 55, figs. 3, 4).

Leptarachnium aurelia, Haeckel, 1879, Manuscript et Atlas.

Cephalis large, nearly hemispherical, with irregular, delicate network of small square meshes. Collar-septum with four large meshes, separated by a cross of four bars, opposite in pairs. Thorax flatly campanulate, with delicate, subregular, hexagonal meshes, and twenty-four prominent radial ribs; four of these are primary or perradial (centrifugal prolongations of the four bars of the collar-septum); four others are interradial or secondary, alternating with the former at angles of 45°; sixteen others are adradial or tertiary, interpolated between the first and second more or less irregularly. In some specimens the disposition of the twenty-four ribs was more regular, in others more irregular, than in the specimen figured (figs. 3, 4). The central capsule (fig. 4) exhibits a flat, cap-shaped part with the nucleus (enclosed in the cephalis), and four large, pear-shaped lobes protruded through the four large collar holes (somewhat deformed in the preparation figured). The wall of the thorax exhibits at the base four larger, nearly semicircular pores, bisected by the four primary thoracic ribs. Peristome with twenty-four indentations (between the prominent distal ends of the twenty-four ribs), often more distinct than in the specimen figured.

Dimensions.—Cephalis 0.03 long, 0.08 broad; thorax 0.1 to 0.2 long, 0.4 to 0.6 broad.

Habitat.—Central Pacific, Station 263 to 274, depth 2350 to 2925 fathoms.

16. Sethophormis dodecaster, n. sp. (Pl. 56, fig. 12).

Cephalis small, flatly cap-shaped, with irregular, small, roundish pores. Thorax flatly conical, nearly of the same shape as in the preceding species, but only with twelve prominent ribs; four primary or perradial ribs (as prolongations of the four crossed cortinar bars), and eight adradial ribs interpolated between the former, and arising at some distance from the collar ring. Peristome with twelve prominent pointed lobes (supported by the distal ends of the twelve ribs), and with twelve semicircular bosoms between them. (The specimen figured is young and not fully developed.)

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.1 long, 0.3 broad.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

17. Sethophormis umbrella, n. sp. (Pl. 70, figs. 4, 5).

Cephalis large, flatly cap-shaped, with irregular, small polygonal meshes. Thorax flat, umbrella-shaped, with subregular, hexagonal meshes, and sixteen strong radial ribs. Four of these are perradial, and centrifugal prolongations of the four crossed collar beams; four others are interradial, and arise, alternating with the former, directly from the horizontal collar ring; eight ribs are adradial or tertiary, and arise in pairs from the four large perradial basal arches of the thorax, which become bisected by the four primary ribs. Peristome irregularly denticulate.

Dimensions.—Cephalis 0.02 long, 0.06 broad; thorax 0.12 long, 0.32 broad.

Habitat.—North Pacific (off Japan), Stations 236 to 239, surface.

18. Sethophormis floscula, n. sp.

Cephalis small, hemispherical, with subregular, small hexagonal pores. Thorax flatly conical, with larger hexagonal meshes and twenty-four ribs; four of these are perradial and prolongations of the four collar bars; four interradial arise from the collar ring between the former, alternating with them. Each of these eight main ribs gives off two more or less irregular, lateral branches (one at each side), altogether sixteen. The thorax is similar to Cladarachnium ramosum (Pl. 55, fig. 5), whilst the cephalis is quite different. Peristome with twenty-four prominent triangular lobes.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.1 long, 0.4 broad.

Habitat.—South Atlantic, Station 325, surface.

19. Sethophormis leptoscenium, n. sp.

Cephalis very small, spherical, with few small, circular pores. Thorax flatly conical or tent-shaped, with concave lateral outlines, small hexagonal meshes, and numerous (thirty to forty or more) strong, little curved, simple radial ribs. Peristome nearly circular, with a corona of small, irregular, conical spines.

Dimensions.—Cephalis 0.015 diameter; thorax 0.07 long, 0.26 broad.

Habitat.—Indian Ocean, Madagascar (Rabbe), surface.

20. Sethophormis leptopilium, n. sp.

Cephalis very small, subspherical, hyaline, without pores. Thorax flatly conical or hat-shaped, with concave lateral outlines, and a very delicate network of small square meshes (similar to Litharachnium araneosum, Pl. 55, fig. 8). This is supported by thirty-two curved radial ribs, four of which are primary, four secondary, and the other twenty-four interpolated. Peristome horizontally expanded and little recurved, like the reflexed brim of a hat.

Dimensions.—Cephalis 0.12 diameter; thorax 0.08 long, 0.24 broad.

Habitat.—South Pacific, Station 291, depth 2250 fathoms.

Genus 559. Sethamphora,^[64] n. gen.

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) with numerous curved ribs in the wall of the ovate thorax, the small mouth of which is constricted. Cephalis without horn.

The genus Sethamphora differs from the preceding Sethophormis, and from the next following ribbed Sethophormida, mainly in the small, more or less constricted mouth; therefore the thorax is more or less ovate, and its ribs curved, with the convexity external. Sethophormis may be divided into two different subgenera, Dictyoprora and Cryptocephalus; in the former the cephalis is perfectly free and well developed, in the latter it is more or less hidden in the uppermost part of the thorax (like Carpocanium).

Subgenus 1. Dictyoprona, Haeckel, 1881, Prodromus, p. 430.

Definition.—Cephalis large, perfectly free, not hidden in the thorax.

1. Sethamphora hexapleura, n. sp.

Shell ovate, smooth, with distinct collar stricture. Length of the two joints = 3 : 11, breadth = 5 : 10. Cephalis large, free, hemispherical, with small circular pores. Thorax truncate, ovate, with six strong curved ribs, and six large triangular meshes between them in the upper half; five smaller pores between every two ribs in the lower half (in three tiers); therefore, together, thirty-six thoracic meshes. Mouth strongly constricted, smooth, only one-third as broad as the thorax.

Dimensions.—Cephalis 0.03 long, 0.05 broad; thorax, 0.11 long, 0.1 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Sethamphora enneapleura, n. sp.

Shell subovate, smooth, with slight collar stricture. Length of the two joints = 3 : 9, breadth = 4 : 8. Cephalis large, hemispherical, free, with small circular pores. Thorax inflated, ovate, with nine strong curved ribs, which are connected by five transverse circular rings at equal distances. Forty-five rounded, squarish, large meshes between them, in five transverse and nine longitudinal rows. Mouth constricted, smooth, half as broad as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.08 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

3. Sethamphora dodecapleura, n. sp.

Shell urceolate, smooth, with sharp collar stricture. Length of the two joints = 3 : 9, breadth = 5 : 9. Cephalis flat, cap-shaped, free, with twelve ribs, and very small pores between them. Thorax thick-walled, inflated, with subcylindrical cavity, and twelve prominent sharp ribs, alternating with twelve longitudinal rows of very small circular pores (eight pores in each row). Mouth constricted, half as broad as the thorax.

Dimensions.—Cephalis 0.03 long, 0.05 broad; thorax 0.09 long, 0.09 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

4. Sethamphora mongolfieri, Haeckel.

Eucyrtidium mongolfieri, Ehrenberg, 1854, Mikrogeol., Taf. xxxiv. fig. 18; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 72, Taf. x. fig. 3.

Shell urceolate, smooth, with distinct collar stricture. Length of the two joints = 2 : 9, breadth = 3 : 7. Cephalis campanulate, with eighteen ribs and small pores. Thorax nearly ellipsoidal, with eighteen prominent ribs, and eighteen longitudinal rows of regular circular pores between them (eight pores in each row; therefore 144 pores altogether). Mouth constricted, only one-third as broad as the thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.09 long, 0.07 broad.

Habitat.—Fossil in Barbados.

5. Sethamphora costata, n. sp. Pl. 62, fig. 3.

Shell urceolate, smooth, very similar to the preceding species; also with eighteen longitudinal ribs, but differing in the larger size of the cephalis and its pores, and in the more slender and ovate form of the thorax. Length of the two joints = 5 : 10, breadth = 5 : 8. Pores of the cephalis more numerous. Mouth half as broad as the thorax.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.1 long, 0.08 broad.

Habitat.—Central Pacific, Stations 265 to 274, depth 2350 to 2925 fathoms.

6. Sethamphora serrata, n. sp.

Shell ovate, spinulate, without external collar stricture. Length of the two joints = 1 : 6, breadth = 2 : 4. Cephalis flat, cap-shaped, with small circular pores. Thorax ovate, truncate, with eighteen serrate longitudinal ribs, alternating with eighteen longitudinal rows of short and broad rather oblong pores (twenty to thirty pores in each row). Mouth strongly constricted, only one-fourth as broad as the thorax.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.12 long, 0.08 broad.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

7. Sethamphora ampulla, Haeckel.

Eucyrtidium ampulla, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 15; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 72, Taf. x. figs. 11, 12.

Shell broad, urceolate, spiny, with sharp collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 5. Cephalis subspherical, with few small pores (in figs. 12a and 12b of Ehrenberg, loc. cit., broken off, so that the four pores of the cortinar septum appear). Thorax inflated, bottle-shaped, with twenty prominent, sharply dentate ribs, alternating with twenty longitudinal rows of circular pores (about eight pores in each row). Mouth flat, constricted, one-third as broad as the thorax.

Dimensions.—Cephalis 0.025 long, 0.03 broad; thorax 0.1 long, 0.14 broad.

Habitat.—Fossil in Barbados.

8. Sethamphora aërostatica, Haeckel.

Podocyrtis aërostatica, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 4.

Shell broad, urceolate, smooth, with sharp collar stricture. Length of the two joints = 2 : 6, breadth = 3 : 8. Cephalis hemispherical, large, with few pores (broken off in fig. 4a of Ehrenberg, so that the six collar pores appear). Thorax inflated, bottle-shaped, with twenty-two to twenty-four smooth prominent ribs, alternating with the some number of longitudinal rows of small circular pores. Mouth very small, strongly constricted, scarcely as broad as the cephalis, with three short teeth.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.08 broad.

Habitat.—Fossil in Barbados.

Subgenus 2. Cryptocephalus, Haeckel, 1881, Prodromus, p. 430.

Definition.—Cephalis more or less hidden in thorax, being partly enveloped by its uppermost part.

9. Sethamphora microstoma, n. sp. (Pl. 57, fig. 5).

Cryptoprora microstoma, Haeckel, Atlas, pl. lvii., fig. 5.

Shell ovate, smooth, without external collar stricture. Length of the two joints = 1 : 6, breadth = 2 : 4. Cephalis flat, cap-shaped, without ribs, with small circular pores. Thorax ovate, with twenty-four prominent ribs, alternating with deep longitudinal furrows, each of which contains a series of about fifteen small circular pores. Mouth very small, representing a short cylindrical tube, which is only one-eighth as broad as the thorax.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.12 long, 0.08 broad.

Habitat.—Western Tropical Pacific, Station 220, depth 1100 fathoms.

10. Sethamphora favosa, n. sp, (Pl. 57, fig. 4).

Cryptocephalus favosus, Haeckel, 1881, Prodromus, p. 430.

Shell ovate, dimply. Length of the two joints = 1 : 5, breadth = 1 : 5. Cephalis subspherical, small, completely hidden in the thickened top of the thorax (but very distinct in the longitudinal section). Thorax ovate, with twenty-five to thirty longitudinal ribs, alternating with the same number of longitudinal furrows, each of which contains ten to twelve circular, hexagonally framed pores. In the smooth wall of the peristome only twelve triangular ribs are visible. Mouth constricted, one-third as broad as the thorax.

Dimensions.—Cephalis 0.02 diameter; thorax 0.1 long, 0.09 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 560. Sethopyramis,^[65] Haeckel, 1881, Prodromus, p. 432 (sensu emendato !)

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) with numerous straight or slightly curved radial ribs in the wall of the pyramidal thorax. Network simple. Cephalis commonly without horn.

The genus Sethopyramis and the four following genera form together a peculiar small group (Sethopyramida), characterised by the slender pyramidal shell, in the wall of which numerous (six to nine or more) radial ribs are enclosed. These ribs may be regarded as the terminal feet of a Calpophæna or Halicalyptra, which become connected by transverse bars. Sethopyramis may be derived also directly from Patagospyris by loss of the primary sagittal ring and reduction of the cephalis.

Subgenus 1. Sestropyramis, Haeckel.

Definition.—Pyramidal shell with six radial main beams (sometimes also five or seven, as individual varieties).

1. Sethopyramis scalaris, Haeckel.

Cornutella scalaris, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 1.

Shell smooth, slenderly pyramidal, hexagonal. Cephalis large, subglobular, hyaline, without pores (or with very small and scarce pores). Thorax with six straight (or little curved) stout longitudinal ribs or radial beams, which are connected by twenty to thirty complete, hexagonal, horizontal rings. The large meshes so produced are regular, square, their length and breadth equally and gradually increasing towards the mouth.

Dimensions.—Cephalis 0.04 diameter; thorax (with twenty-four transverse rings) 0.4 long, 0.15 broad at the mouth.

Habitat.—Fossil in Barbados.

2. Sethopyramis hexalactis, n. sp.

Shell thorny, of the same form as, and similar structure to, the preceding species, but differing in the spiny surface and the smaller subglobular cephalis, which bears small circular pores and an oblique conical horn twice the length. The whole surface is covered with short conical thorns.

Dimensions.—Cephalis 0.02 diameter; thorax (with twenty transverse rings) 0.25 long, 0.1 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Subgenus 2. Cephalopyramis, Haeckel, 1881, Prodromus, p. 432.

Definition.—Pyramidal shell with nine radial main beams (sometimes also eight or ten, as individual varieties).

3. Sethopyramis enneactis, n. sp. (Pl. 56, fig. 7).

Cephalopyramis enneactis, Haeckel, 1881, Prodromus et Atlas, pl. lvi. fig. 7.

Shell smooth, slender, pyramidal. Cephalis large, ovate, with pointed apex, nearly hyaline, with very few and small scattered pores. Thorax very slenderly pyramidal, with straight lateral outlines, and nine stout and straight radial beams, which are connected by fifteen to twenty horizontal complete rings. Meshes subregular, square, simple, without secondary network; their length and breadth equally increasing towards the mouth.

Dimensions.—Cephalis 0.05 long, 0.03 broad; thorax (with twenty transverse rings) 0.24 long, 0.1 broad at the mouth.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms.

4. Sethopyramis quadrata, n. sp. (Pl. 54, fig. 2).

Shell smooth, slenderly pyramidal, very similar in form and structure to the preceding species; differing from it in the rudimentary cephalis, which is very small, hemispherical, with few small porules. The three internal cortinar bars of the collar stricture are present; when they become lost this species passes over into Bathropyramis quadrata (Pl. 54, fig. 1).

Dimensions.—Cephalis 0.01 long, 0.02 broad; thorax (with ten transverse rings) 0.15 long, 0.1 broad at the mouth.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

5. Sethopyramis quadratella, Haeckel.

Cornutella quadratella, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 2. Litharachnium quadratella, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol, xxxvi. p. 540, Taf. xxxiii. fig. 37.

Shell smooth, broadly pyramidal. Cephalis ovate, small, blunt, hyaline, with very few and small pores (in the figure of Ehrenberg broken off). Thorax broadly pyramidal, with straight lateral outlines, and nine stout and straight radial beams, which are connected by eight to twelve horizontal complete rings. Meshes in the upper half regular, square, in the lower half broad, rectangular (in the tenth transverse row twice as broad as long).

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax (with ten transverse rings) 0.15 long, 0.15 broad.

Habitat.—Fossil in Barbados.

6. Sethopyramis trapezoides, n. sp.

Shell smooth, broadly pyramidal. Cephalis large, ovate, hyaline, without pores; its collar septum exhibits distinctly the four collar pores (two larger cardinal and two smaller jugular pores). Thorax broad, pyramidal, with slightly concave lateral outlines and nine (sometimes eight or ten) curved ribs, which are connected by eighteen to twenty-four complete transverse rings. The large meshes, so produced, have the form of a parallel trapezoid, and are in the eighth transverse row three times as broad as long. (Differs from Bathropyramis trapezoides, Pl. 54, fig. 3, mainly by the possession of a well developed cephalis).

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax (with eighteen rings) 0.32 long, 0.24 broad.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

7. Sethopyramis spinosa, n. sp.

Shell thorny, slender, pyramidal. Cephalis small, subspherical, with few small pores and a straight, vertical, conical horn twice the length. Thorax with nine straight ribs, which are connected by sixteen to twenty complete transverse nine-angled rings. The large meshes so produced are subregular, square. From each nodal point a short conical spine arises. (Differs from the similar Bathropyramis spinosa, Pl. 54, fig. 4, by the development of the cephalis and the simple pointed, unforked spines.)

Dimensions.—Cephalis 0.03 diameter; thorax (with sixteen rings) 0.2 long, 0.12 broad.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

8. Sethopyramis hexagonalis, n. sp.

Shell papillate, slender, pyramidal. Cephalis small, hemispherical, with a straight conical horn twice the length, and small circular pores. Thorax conical, with slightly convex outlines and nine stout, somewhat curved ribs in zig-zag form, which are connected by ten to twelve interrupted transverse bars. From each nodal point a small conical papilla arises. The large meshes so produced are regular, hexagonal, gradually increasing in size towards the mouth.

Dimensions.—Cephalis 0.03 diameter; thorax (with twelve transverse rows of meshes) 0.18 long, 0.12 broad.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms.

9. Sethopyramis cyclomma, n. sp.

Shell thorny, slender, pyramidal. Cephalis large, subspherical, with numerous very small circular pores, and a small conical horn of the same length. Thorax similar in form and structure to that of the preceding species; but each hexagonal mesh is provided with a very thin circular hyaline ring (like a diaphragm), so that the openings are not hexagonal, but circular. From each nodal point a short pointed conical or slightly forked spine arises.

Dimensions.—Cephalis 0.02 diameter; thorax (with ten transverse rows of meshes) 0.18 long, 0.14 broad.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

Subgenus 3. Actinopyramis, Haeckel.

Definition.—Pyramidal shell with twelve or more radial beams (commonly twelve to twenty-four, sometimes forty or more).

10. Sethopyramis dodecalactis, n. sp.

Shell smooth, slender, pyramidal. Cephalis small, spherical, hyaline, with a short conical horn. Thorax with twelve radial ribs in the upper half, between which twelve others are interpolated in the lower half. These are connected by twenty to twenty-four complete transverse rings. The meshes so produced are subregular, rectangular.

Dimensions.—Cephalis 0.03 diameter; thorax 0.6 long, 0.2 broad.

Habitat.—Indian Ocean, Madagascar (Rabbe), surface.

11. Sethopyramis bicornis, n. sp.

Shell spiny, slender, pyramidal. Cephalis small, spherical, hyaline, with two divergent conical horns, the major (occipital) three times and the minor (frontal) twice as long. Thorax slender, pyramidal, campanulate, thorny, with twenty to thirty radial beams, which are little curved, convex in the upper, concave in the lower half, and connected by numerous interrupted transverse bars. Meshes in the upper third rounded, in the lower two-thirds quadrangular, of very different sizes. Surface covered with spinules.

Dimensions.—Cephalis 0.02 diameter; thorns 0.9 long, 0.4 broad.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

12. Sethopyramis maxima, n. sp.

Shell smooth, slender, pyramidal. Cephalis small, spherical, with few small pores, and a stout, vertical, conical horn twice the length. Thorax very prolonged, conical, with straight lateral outlines and numerous (twenty to fifty) radial beams (in the upper third twelve, in the middle third twenty-four, in the lower third forty to fifty, by interpolation); they are connected by very numerous interrupted transverse bars. Meshes subregular, quadrangular. Surface smooth.

Dimensions.—Cephalis 0.02 diameter; thorax 1.05 long, 0.45 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 561. Plectopyramis,^[66] Haeckel, 1881, Prodromus, p. 432.

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) with numerous straight or slightly curved radial ribs in the wall of the pyramidal thorax. Network double, the large primary meshes being fenestrated by fine secondary network. Cephalis commonly without horn.

The genus Plectopyramis differs from the preceding Sethopyramis, its ancestral form, only in the peculiar double fenestration of the shell, the large primary meshes of which are separated by strong bars, and filled up by a very delicate arachnoidal network, composed of small pores and very thin threads between them. This double lattice-work often exhibits a very remarkable regularity. As in the preceding genus, the number of radial ribs is commonly six or nine, rarely twelve to twenty or more.

Subgenus 1. Hexapleuris, Haeckel.

Definition.—Pyramidal shell with six radial main beams (sometimes five or seven in individual varieties).

1. Plectopyramis magnifica, Haeckel.

Polycystina magnifica, Bury, 1862, Polycystins of Barbados, pl. xi. fig.

Shell smooth, slender, pyramidal. Cephalis large, ovate, pointed, separated from the thorax by a very deep collar stricture, with few irregular pores. Thorax with six strong and straight radial beams, which are connected by about twenty horizontal, hexagonal rings. The large meshes so produced are regular, square, and filled up by an extremely delicate secondary arachnoidal network, composed of regular square pores (as in Pl. 54, figs. 7, 8).

Dimensions.—Cephalis 0.06 long, 0.04 broad; thorax (with twenty transverse rings) 0.4 long, 0.12 broad.

Habitat.—Fossil in Barbados.

2. Plectopyramis hexapleura, n. sp.

Shell thorny, slender, pyramidal. Cephalis large, ovate, blunt, with deep collar stricture. Thorax with six strong and straight radial beams, which are connected by numerous (twenty to thirty) interrupted transverse bars. The large meshes so produced are irregular, quadrangular, and filled up by irregular, delicate, secondary network, with small polygonal pores.

Dimensions.—Cephalis 0.05 long, 0.03 broad; thorax 0.3 long, 0.1 broad.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 2. Enneapleuris, Haeckel.

Definition.—Pyramidal shell with nine radial main beams (sometimes eight or ten in individual varieties).

3. Plectopyramis dodecomma, n. sp. (Pl. 54, fig. 6).

Shell smooth, slenderly pyramidal, with straight outlines. Cephalis conical, obtuse, with thirty-six small square pores (in nine divergent longitudinal rows, each of four pores). Collar septum (between cephalis and thorax) with four distinct collar pores. Thorax pyramidal, with nine very stout and straight angular radial beams, which are connected by ten to fifteen broad horizontal nine-angled rings. Each of the large regular, square meshes so produced contains a very delicate fenestration, with twelve regular, square pores, separated by two transverse and three longitudinal crossed threads. A very regular and remarkable structure.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax (with ten rings) 0.2 long, 0.15 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

4. Plectopyramis quadratomma, n. sp.

Shell smooth, slenderly pyramidal. Cephalis large, ovate, hyaline, with few very small basal pores and deep collar stricture. Thorax pyramidal, with straight outline, and nine very stout and straight radial beams, which are connected by fifteen to twenty horizontal nine-angled rings. Each of the large regular, square meshes so produced is filled up by a very delicate arachnoidal network, with very numerous and small square pores (as in the similar Cinclopyramis infundibulum, Pl. 54, fig. 7, which differs in the loss of the cephalis).

Dimensions.—Cephalis 0.05 long, 0.03 broad; thorax (with fifteen rings) 0.32 long, 0.2 broad.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

5. Plectopyramis trapezomma, n. sp. (Pl. 54, fig. 8).

Shell smooth, broadly pyramidal, with concave lateral outlines. Cephalis hemispherical, small, with numerous small, circular pores. Thorax pyramidal, with nine stout, concavely curved radial beams, which are connected by twelve to sixteen horizontal nine-angled rings. The large meshes so produced are in the upper half square, in the lower half parallel trapezoid (in the fifteenth ring three times as broad as long), and filled up by a secondary arachnoidal network, with very numerous and small square pores.

Dimensions.—Cephalis 0.015 long, 0.025 broad; thorax (with fifteen rings) 0.22 long, 0.2 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

6. Plectopyramis polygonomma, n. sp.

Shell smooth, pyramidal, very similar to the preceding species; differing from it in the irregular shape of the delicate polygonal (not tetragonal) secondary network, filling up the large rectangular meshes. The cephalis is larger, hyaline, pear-shaped, pointed, without pores, with a deep collar stricture. The nine radial beams of the thorax are less concave.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax (with fifteen rings) 0.3 long, 0.22 broad.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

7. Plectopyramis heteromma, n. sp.

Shell smooth, slenderly pyramidal, with concave outlines. Cephalis very small, subspherical, with a small oblique, conical horn, and very small, scarce circular pores. Thorax with nine stout concavely curved radial beams, which are connected by numerous (thirty to fifty or more) interrupted transverse bars. The large irregular meshes so produced are filled up by irregular, polygonal, delicate lattice-work.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.6 long, 0.3 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

8. Plectopyramis serrata, n. sp.

Shell thorny, slenderly pyramidal, with straight outlines. Cephalis very small, spherical, with a long oblique, conical horn, and very small circular pores. Thorax with nine stout, straight, regularly serrate ribs or radial beams, which are connected by numerous (twenty to thirty or more) interrupted transverse bars. The latter, being crossed by intercalated and interrupted irregular radial beams, produce a subregular secondary network of rectangular meshes of different sizes.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax, 0.3 long, 0.2 broad.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

9. Plectopyramis fenestrata, Haeckel.

Pyramis fenestrata, Bury, 1862, Polycystins of Barbados, pl. xxi. fig. 8.

Shell thorny, broadly pyramidal, with straight outlines. Cephalis very small, spherical, hyaline. Thorax with nine stout, spinulate, straight ribs or radial beams, which are connected by ten to fifteen transverse bars, which in the upper half are complete rings, in the lower half interrupted, and crossed by irregularly intercalated radial beams. Meshes therefore irregular, quadrangular. All the bars are thorny.

Dimensions.—Cephalis 0.01 diameter; thorax 0.2 long, 0.16 broad.

Habitat.—Tropical Atlantic.

10. Plectopyramis furcata, n. sp.

Shell spiny, slenderly pyramidal, with straight outlines. Cephalis small, spherical, with few small pores. Thorax with nine stout and straight spinulate ribs, which are connected by a variable number of irregular interrupted transverse bars; the large quadrangular meshes so produced are filled up by irregular delicate network. The entire surface of the thorax is covered with short forked spines.

Dimensions.—Cephalis 0.02 diameter; thorax 0.3 long, 0.2 broad.

Habitat.—Indian Ocean (Zanzibar), Pullen, depth 2200 fathoms.

Subgenus 3. Polypleuris, Haeckel.

Definition.—Pyramidal shell with numerous (twelve or more) radial main beams (commonly twelve to eighteen, sometimes twenty to thirty or more).

11. Plectopyramis polypleura, n. sp. (Pl. 56, fig. 8).

Shell smooth, slenderly conical, with straight outlines. Cephalis small, subspherical, with very small dot-like pores, and an oblique conical horn twice the length. Thorax with numerous (twenty to thirty) divergent longitudinal ribs; usually twelve of these radial beams appear as stronger, primary main ribs, and twelve to eighteen other as secondary, feebler, interpolated ribs. They are crossed by numerous (twenty to forty or more) horizontal rings. The large meshes so produced are quadrangular, and partly filled up by a very delicate secondary network, with small square pores.

Dimensions.—Cephalis 0.03 diameter; thorax 0.36 long, 0.24 broad.

Habitat.—Central Pacific, Station 267, depth 2700 fathoms.

12. Plectopyramis lagena, n. sp.

Shell smooth, wine-bottle shaped, or slenderly conical-campanulate, with bent outlines, which are concave in the upper, convex in the lower half. Cephalis very small, spherical, hyaline, without pores. Thorax with twenty-four radial ribs, twelve stronger primary, alternating with twelve feebler secondary. They are crossed by interrupted transverse bars. The irregular quadrangular meshes so produced are filled up by a delicate, irregular, secondary network.

Dimensions.—Cephalis 0.02 diameter; thorax 0.5 long, 0.3 broad.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms.

Genus 562. Spongopyramis,^[67] n. sp.

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) with numerous straight or slightly curved radial ribs in the wall of the pyramidal thorax. Network spongy. Cephalis commonly without horn.

The genus Spongopyramis has arisen from Sethopyramis by development of an irregular spongy framework around the lattice-shell, and is one of the small number of Cyrtoidea in which the shell-wall exhibits a spongy structure. In both observed species the cephalis is small, but evident.

1. Spongopyramis spongiosa, n. sp. (Pl. 56, fig. 10).

Plectopyramis spongiosa, Haeckel, 1881, Prodromus et Atlas, loc. cit.

Shell partly or entirely enveloped by spongy framework, slender, pyramidal, with rather straight outlines. Cephalis very small, ovate, hyaline. Thorax with nine very stout and nearly straight ribs, which are connected by fifteen to twenty or more irregular, interrupted transverse bars. The irregular quadrangular meshes so produced are filled up by an irregular secondary network, with meshes of very different size and form. The dense spongy envelope, which in the specimen figured covered only half the shell, was complete in another older specimen.

Dimensions.—Cephalis 0.015 long, 0.01 broad; thorax 0.4 long, 0.25 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Spongopyramis spongoplecta, n. sp.

Shell entirely enveloped by spongy framework, pyramidal, with straight outlines. Cephalis ovate (twice as large as in the preceding species), with small circular pores. Thorax with twelve stout and straight ribs, which are connected by twenty to twenty-five annular, transverse bars. The subregular square meshes so produced are filled up by irregular, spongy network, which envelops the whole shell more loosely than in Spongopyramis spongiosa.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.5 long, 0.2 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Genus 563. Acanthocorys,^[68] Haeckel, 1881, Prodromus, p. 432.

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) with numerous radial ribs in the wall of the pyramidal thorax, prolonged into divergent terminal feet. Network simple. Cephalis commonly with several horns.

The genus Acanthocorys and the following nearly allied Arachnocorys possess a near relation to the three preceding pyramidal genera, but differ from them in the terminal prolongation of the radial ribs, which are commonly spiny and form a corona of free feet around the mouth of the thorax. The cephalis is usually much larger than in the three preceding genera, and bears a variable number of radial horns. Therefore these two genera are probably older and nearer to the common ancestral form of the Sethophormida than the preceding genera. It may be derived directly from Dictyophimus by interpolation of three secondary (interradial) ribs between the three primary (perradial) ribs.

Subgenus 1. Acanthocorallium, Haeckel.

Definition.—Thorax with six divergent ribs or radial beams (three primary or perradial alternating with three secondary or interradial).

1. Acanthocorys hexapodia, n. sp.

Cephalis large, ovate, with subregular hexagonal pores, and six strong, conical, simple, divergent horns of the same length. Thorax flat, conical, smooth, with six large triangular basal holes, separated by six strong, prismatic, smooth beams, which are connected only near the distal end by a hexagonal ring of delicate, irregular network. Collar septum with three meshes, separated by the three centripetal prolongations of the three primary ribs.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.12 long, 0.24 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

2. Acanthocorys pristipodia, n. sp.

Cephalis large, hemispherical, with irregular, polygonal pores, and numerous (ten to twenty) bristle-shaped, radiating horns, which are conical at the base, and twice as long. Thorax flatly campanulate, thorny, with six strong, serrate or spinulate, divergent, radial ribs, prolonged into six free conical feet of the same length. Meshes of the thorax irregular, polygonal, a corona of six larger ones at the base. Collar septum with four meshes, shaped as in Pl. 56, fig. 6.

Dimensions.—Cephalis 0.04 long, 0.06 broad; thorax 0.08 long, 0.18 broad.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

3. Acanthocorys macropodia, n. sp.

Cephalis small, subspherical, with irregular, roundish pores and numerous small, bristle-shaped horns. Length of the two joints = 1 : 2, breadth = 1 : 6. Thorax sexangular, pyramidal, with six very long and straight, widely divergent feet, which are prismatic and spiny, and three to five times as long as the breadth of the shell. Only the upper third of the six ribs is connected by irregular, roundish network, with six large triangular holes at the base. Collar septum with four meshes which have the same relation to the six ribs as in Sethophormis hexalactis (Pl. 56, fig. 6).

Dimensions.—Cephalis 0.025 diameter, thorax 0.05 long, 0.15 broad.

Habitat.—Central Pacific, Station 271, surface.

4. Acanthocorys bütschlii, Haeckel.

? Clathrocanium ehrenbergii, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. pp. 514, 539, Taf. xxxii. fig. 18, a, b.

Cephalis large, subspherical, with numerous small, circular pores and three to six divergent, slender, apical horns. Thorax flatly conical, smooth, not much larger than the cephalis, with six large, triangular or ovate basal holes between the six ribs. Three of these ribs are primary or perradial, and arise immediately from the collar septum, alternating with three secondary or interradial ribs, which arise more outside. The specimen observed by me exhibited six apical horns, and was more complete than that figured by Bütschli, the six ribs being prolonged over the connecting lattice-girdle into six short, divergent feet.

Dimensions.—Cephalis 0.06 long, 0.06 broad; thorax 0.08 long, 0.1 broad.

Habitat.—Fossil in Barbados.

Subgenus 2. Acanthocoronium, Haeckel.

Definition.—Thorax with nine divergent ribs or radial beams, three of which are primary or perradial, the other six secondary or interradial.

5. Acanthocorys umbellifera, Haeckel.

Arachnocorys umbellifera, Haeckel, 1862, Monogr. d. Radiol., p. 305, Taf. vi. fig. 12.

Cephalis large, ovate, with subregular, circular pores and numerous divergent, simple spines of different lengths. Thorax flatly conical, with nine strong, divergent ribs, which in the distal half are free, in the proximal half connected by numerous transverse beams, forming irregular polygonal meshes. Dorsal face of the thorax armed with scattered ascending spines.

Dimensions.—Cephalis 0.05 long, 0.035 broad; thorax 0.05 long, 0.12 broad.

Habitat.—Mediterranean (Messina); Atlantic, Station 354, surface.

6. Acanthocorys triloba, n. sp.

Cephalis large, campanulate, trilobed, with irregular, roundish pores, numerous spines, and a large pyramidal horn on the top, which is connected by three constricted arches with the base of the horizontal collar beams. From the latter arise as centrifugal prolongations three stout, curved, primary ribs of the flatly vaulted thorax, and each of these gives off at the base two opposite, lateral, secondary ribs. These nine ribs are spiny, and connected by irregular, arachnoidal network.

Dimensions.—Cephalis 0.05 long, 0.07 broad; thorax 0.08 long, 0.18 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

7. Acanthocorys enneapodia, n. sp.

Cephalis large, ovate, with irregular roundish pores, and numerous divergent, ascending spines. Thorax smooth, conical, little larger, with the same network, and nine larger, triangular holes at the base; with nine straight, equally-disposed ribs, which are prolonged into slender feet twice the length. With these latter alternate nine shorter radial spines, arising from the truncate peristome.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.05 long, 0.09 broad.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

8. Acanthocorys macroceras, n. sp. (Pl. 97, fig. 12).

Cephalis large, hemispherical, spiny, with regular, circular pores, and a very large, cylindrical, vertical horn five times as long as the whole shell. Thorax spiny, campanulate, with irregular, roundish pores and nine strong, curved ribs, prolonged into nine slender, divergent feet twice the length, which are curved, convex in the proximal half and concave in the distal half.

Dimensions.—Cephalis 0.05 long, 0.08 broad; thorax 0.12 long, 0.2 broad.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

9. Acanthocorys furcata, n. sp.

Cephalis large, subspherical, spiny, with irregular, roundish pores. Thorax flatly conical, thorny, with irregular, polygonal pores, decreasing in size toward the mouth, and with nine straight divergent ribs, which at the peristome are forked and prolonged into eighteen slender, very long, bristle-shaped feet.

Dimensions.—Cephalis 0.045 diameter, thorax 0.07 long, 0.13 broad.

Habitat.—South Atlantic, Station 323, depth 1900 fathoms.

Subgenus 3. Acanthocorythium, Haeckel.

Definition.—Thorax with a variable number (ten to twenty or more) radial ribs, prolonged into free terminal feet.

10. Acanthocorys dodecaster, n. sp.

Cephalis small, subspherical, with small circular pores and a large conical horn of twice the length, and some accessory spines. Thorax thorny, flatly campanulate, with twelve stout curved ribs, which at the peristome are prolonged into twelve slender, curved feet of twice the length; four of them are centrifugal prolongations of the four cortinar beams separating the four large meshes of the collar septum; eight other ribs are secondary, interpolated in pairs between the former. At the base of the thorax are twelve large triangular holes between the ribs; the other network is irregular, with polygonal meshes.

Dimensions.—Cephalis 0.03 diameter, thorax 0.05 long, 0.12 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

11. Acanthocorys polypodia, n. sp.

Cephalis small, hemispherical, with small, roundish pores and divergent radial spines. Thorax flatly conical, spiny, with twenty to twenty-four divergent, straight ribs, which in the proximal third are separated by the same number of large, triangular meshes, in the middle third connected by irregular network, in the distal third free.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.15 broad.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

Genus 564. Arachnocorys,^[69] Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 837.

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) with numerous radial ribs in the wall of the pyramidal thorax, prolonged into divergent terminal feet. Network double, with an arachnoidal outer mantle around the inner lattice-shell. Cephalis commonly with numerous horns.

The genus Arachnocorys has been derived from the preceding Acanthocorys, by development of numerous external siliceous threads which connect the radial horns of the cephalis with the secondary spines arising from the thoracic ribs. In this way there becomes formed an outer arachnoidal framework, enveloping loosely, like a delicate mantle, the inner primary lattice-shell.

Subgenus 1. Arachnocorallium, Haeckel.

Definition.—Thorax with six divergent ribs or radial beams (three primary or perradial, alternating with three secondary or interradial).

1. Arachnocorys hexaptera, n. sp.

Arachnocorys circumtexta (juv.?), R. Hertwig, 1879, Organism. d. Radiol., p. 79, Taf. viii. fig. 2a.

Cephalis large, subspherical, with irregular, polygonal pores, and numerous bristle-shaped spines twice the length; on the centre of the top a single larger vertical horn. Thorax flatly conical, with six strong and straight widely divergent ribs, which in the proximal half are separated by six large holes, in the distal half connected by a broad ring of irregular network. From each rib arises a perpendicular branch, and these branches are connected together, and with the spines of the cephalis, by arachnoidal network.

Dimensions.—Cephalis 0.04 diameter, thorax 0.08 long, 0.24 broad.

Habitat.—Central Pacific, Station 266; Mediterranean, surface.

2. Arachnocorys discoides, n. sp.

Cephalis small, pyramidal, with irregular, roundish pores and numerous thin spines, on the top a single larger vertical horn. Thorax very flat, nearly discoidal, with six strong and straight ribs, which by communication of few larger and numerous smaller branches form an irregular network with polygonal meshes. From each of the six ribs arise two or three larger, perpendicular branches of half the length, and from the network numerous smaller spines. All these dorsal spines of the shell are connected by a dense arachnoidal wicker-work.

Dimensions.—Cephalis 0.02 diameter, thorax 0.04 long, 0.3 broad.

Habitat.—Central Pacific, Station 271, surface.

Subgenus 2. Arachnocoronium, Haeckel.

Definition.—Thorax with nine divergent ribs or radial beams, three of which are primary or perradial, the other six secondary or interradial. (Sometimes eight or ten occur instead of the nine normal ribs.)

3. Arachnocorys circumtexta, Haeckel.

Arachnocorys circumtexta, Haeckel, 1862, Monogr. d. Radiol., p. 304, Taf. vi. figs. 9-11. Arachnocorys circumtexta, R. Hertwig, 1879, Organism. d. Radiol., p. 78, Taf. viii. fig. 2.

Cephalis large, subspherical, with numerous roundish pores, and eight to ten slender, conical horns twice the length. Thorax flatly conical, with nine strong, straight, widely divergent, conical feet, each of which bears in the middle of its outer side a perpendicular ascending branch of half the length. These branches and the horns of the cephalis are connected by very thin, parallel, arachnoidal threads. Network of the thorax irregular, with nine larger triangular holes at the base. Collar septum with numerous, irregular, roundish pores.

Dimensions.—Cephalis 0.04 to 0.05 diameter, thorax 0.08 to 0.12 long, 0.15 to 0.25 broad.

Habitat.—Mediterranean (Messina); Atlantic, Stations 347 to 354, surface.

4. Arachnocorys enneaptera, n. sp.

Cephalis large, campanulate, with irregular, polygonal pores, two larger stout pyramidal and numerous slender, bristle-shaped horns. Thorax of the same structure as in the preceding species, only the nine basal holes are of twice the size; the lower network denser (as in Clathrocanium diadema, Pl. 64, fig. 2). Collar septum with numerous, irregular, roundish pores.

Dimensions.—Cephalis 0.05 diameter, thorax 0.12 long, 0.22 broad.

Habitat.—Tropical Atlantic, Station 338, surface.

5. Arachnocorys araneosa, n. sp. (Pl. 56, fig. 11).

Cephalis large, subspherical, with circular, subregular, hexagonally framed pores, and twenty to thirty slender, cylindrical, straight radial spines. Thorax flatly conical, nearly of the same shape as in the two preceding species, but with nine longer ribs, and more irregular, broader network between them. From the middle of each rib arises, nearly horizontally, a strong branch, which is directed outwards. These branches are connected with the spines of the cephalis as well as with the distal half of the ribs, by dense and delicate arachnoidal network, composed of parallel, very thin, siliceous threads (in fig. 11 only partially represented). Collar septum with numerous irregular, roundish pores.

Dimensions.—Cephalis 0.04 diameter, thorax 0.1 long, 0.2 broad.

Habitat.—Central Pacific, Station 270 to 274, surface.

6. Arachnocorys arachnodiscus, n. sp.

Cephalis small, campanulate, conical, with a single very large conical central horn, and numerous smaller accessory spines. Thorax in form and structure similar to that of the three preceding species, but much flatter, being nearly discoidal. The meshes of the network are smaller and more numerous, irregularly polygonal, and the nine basal holes little larger. Collar septum with four large meshes (as in Pl. 60, fig. 6).

Dimensions.—Cephalis 0.25 long, 0.3 broad; thorax 0.04 long, 0.24 broad.

Habitat.—North Pacific, Station 248, surface.

7. Arachnocorys trifida, n. sp.

Cephalis large, campanulate, with irregular, roundish pores and numerous ramified spines; in the centre of the top a larger pyramidal oblique horn of twice the length. Thorax cap-shaped, flatly vaulted, with nine strong convex ribs, prolonged into slender free feet. Three of these nine ribs are the centrifugal prolongations of the three cortinar bars (united in the centre of the collar stricture, separating its three large cortinar meshes); the other six are diverging lateral branches of the former, arising in pairs at both sides of its base. All nine ribs are connected by delicate arachnoidal network with irregular polygonal meshes. From its surface arise thin bristles, and from the base of each main rib a stout, perpendicular branch. All these dorsal spines are connected by irregular, arachnoidal wicker-work, covering thorax and cephalis. (A remarkable primitive species?)

Dimensions.—Cephalis 0.05 long, 0.06 broad; thorax 0.07 long, 0.18 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subgenus 3. Arachnocorythium, Haeckel.

Definition.—Thorax with a variable number of radial ribs (twelve to twenty or more), prolonged into free terminal feet.

8. Arachnocorys polyptera, n. sp.

Cephalis large, subspherical, with irregular, roundish pores and numerous radial spines. Thorax flatly conical, with numerous radial ribs (twenty to thirty), which are in the distal half free, in the proximal half connected by delicate arachnoidal wicker-work, with polygonal, irregular meshes. From its dorsal face arise numerous radial spines, which are connected together, and with the cephalic spines, by very thin and numerous threads, parallel between every two spines. Similar to Arachnocorys araneosa (Pl. 56, fig. 11), but differing in the structure of the cephalis, and in the greater number of the ribs and spines.

Dimensions.—Cephalis 0.04 diameter, thorax 0.12 long, 0.24 broad.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

Genus 565. Anthocyrtoma,^[70] n. gen.

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) without thoracic ribs, with six terminal feet around the mouth. Cephalis free, with an apical horn.

The genus Anthocyrtoma and the four following genera form together the peculiar group of Carpocanida, comprising all those Sethophormida in which the original thoracic ribs are lost, and only the terminal feet remain. Anthocyrtoma is the simplest form of this group, possessing only six terminal feet, three primary perradial, and three alternating, secondary, interradial. It may be directly derived either from Lychnocanium, by interpolation of three interradial feet, or from Hexaspyris by loss of the sagittal ring.

1. Anthocyrtoma serrulata, Haeckel.

Anthocyrtis serrulata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. vi. fig. 7.

Shell pear-shaped, rough, with obliterated collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 3. Cephalis ovate, with very small pores, and a stout conical horn of the same length. Abdomen inflated, truncate, with larger, regular, circular pores, twice as broad as the constricted mouth. Six feet vertical, parallel, serrate, all of the same size, about as long as the cephalis.

Dimensions.—Cephalis 0.06 long, 0.05 broad; thorax 0.2 long, 0.17 broad.

Habitat.—Fossil in Barbados.

2. Anthocyrtoma alterna, n. sp.

Shell pear-shaped, smooth, with distinct collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 6. Cephalis hemispherical, with a slender conical horn of twice the length. Abdomen inflated, subglobular, with regular, circular, hexagonally framed pores, three times as broad as the narrow, constricted mouth. Six feet conical, smooth, somewhat divergent, alternating, of different sizes; the three larger (perradial) half as long as the shell, and twice as long as the three smaller (interradial). (Similar to Anthocyrtis ventricosa.)

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.15 long, 0.18 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 566. Anthocyrtis,^[71] Ehrenberg, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1847, p. 54.

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) without thoracic ribs, with nine terminal feet around the mouth. Cephalis free, with an apical horn.

The genus Anthocyrtis (in the original definition of Ehrenberg) contained all Dicyrtida without thoracic ribs, with terminal feet. We here restrict the definition to those Sethophormida in which the number of free terminal feet is constantly nine (three primary perradial and three alternate pairs of secondary interradial feet). Anthocyrtis may be derived either directly from Patagospyris by loss of the sagittal ring, or from Lychnocanium by interpolation of three secondary feet.

Subgenus 1. Anthocyrtella, Haeckel.

Definition.—Feet of the peristome-corona divergent, their basal distance less than their terminal distance.

1. Anthocyrtis mespilus, Ehrenberg.

Anthocyrtis mespilus, Ehrenberg, 1854, Taf. xxxvi. fig. 13; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 66, Taf. vi. fig. 4 (not 5).

Shell smooth, with distinct collar stricture. Length of the two joints = 1 : 5, breadth = 2 : 6. Cephalis hemispherical, with a stout pyramidal horn of twice the length. Thorax nearly hemispherical, with regular, circular, quincuncial pores. Mouth scarcely constricted, with nine divergent, triangular, lamellar feet, about as long as the thorax.

Dimensions.—Cephalis 0.012 long, 0.02 broad; thorax 0.05 long, 0.06 broad.

Habitat.—Fossil in Barbados.

2. Anthocyrtis furcata, Ehrenberg.

Anthocyrtis furcata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 64, Taf. vi. fig. 2.

Shell smooth, with deep collar stricture. Length of the two joints = 1 : 5, breadth = 2 : 6. Cephalis hemispherical, with a short pyramidal horn of half the length. Thorax hemispherical, with large, irregular, roundish pores. Mouth scarcely constricted, with nine divergent, curved, slender feet, which are about as long as the shell, and forked at the distal end.

Dimensions.—Cephalis 0.01 long, 0.02 broad; thorax 0.05 long, 0.06 broad.

Habitat.—Fossil in Barbados.

3. Anthocyrtis butomus, n. sp.

Shell thorny, with obliterated collar stricture. Length of the two joints = 2 : 6, breadth = 2 : 7. Cephalis ovate, with very small and scarce pores, and a conical horn of the same length. Thorax inflated, pear-shaped, with regular, circular, quincuncial pores. Mouth about half as broad, constricted, with nine divergent, broad, nearly square, lamellar feet, half as long as the thorax (similar to Anthocyrtis serrulata, Ehrenberg, loc. cit., Taf. vi. fig. 7).

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.12 long, 0.14 broad.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

4. Anthocyrtis ventricosa, Ehrenberg.

Anthocyrtis ventricosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. viii. fig. 1.

Shell thorny, with obliterated collar stricture. Length of the two joints = 1 : 7, breadth = 2 : 7. Cephalis hemispherical, hyaline, without pores, with a slender, conical horn, of about the same length. Thorax inflated, pear-shaped or subspherical, with regular, circular, quincuncial pores. Mouth only one-third as broad, much constricted, with nine divergent, slender, conical feet, about one-fifth as long as the diameter of the shell (partly broken off in Ehrenberg's figure).

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.14 long, 0.14 broad.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms; also fossil in Barbados.

Subgenus 2. Anthocyrtissa, Haeckel.

Definition.—Feet of the peristome-corona parallel, vertical; their basal and terminal distances equal.

5. Anthocyrtis ophirensis, Ehrenberg.

Anthocyrtis ophirensis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 285, Taf. ix. fig. 13.

Shell smooth, with slight collar stricture. Length of the two joints = 2 : 4, breadth = 1 : 5. Cephalis ovate, with irregular, roundish pores, and a pyramidal, excentric, vertical horn of the same length. Thorax campanulate, with delicate network of large, regular, hexagonal pores. Mouth scarcely constricted, with nine parallel, vertical, conical feet, about as long as the cephalis. (In the specimen figured by Ehrenberg only seven feet are represented, two being broken off; two other specimens of this species, captured by Rabbe, exhibited nine regularly disposed feet.)

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.08 long, 0.1 broad.

Habitat.—Indian Ocean, Zanzibar (Pullen); Madagascar (Rabbe), surface.

6. Anthocyrtis lauranthus, n. sp.

Shell smooth with slight collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 4. Cephalis ovate, with large, roundish pores, and a conical horn of twice the length. Thorax inflated, campanulate, with regular, circular, hexagonally framed pores. Mouth two-thirds as broad, little constricted, with nine parallel, vertical, broad, lamellar, triangular feet, half as long as the cephalis.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.1 long, 0.12 broad.

Habitat.—Central Pacific, Station 266 to 270, depth 2550 to 2925 fathoms.

7. Anthocyrtis grossularia, Ehrenberg.

Anthocyrtis grossularia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 64, Taf. vi. fig. 6.

Shell spiny, with deep collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 4. Cephalis subspherical, thorny, with a conical horn of the same length. Thorax ovate, spiny, with numerous densely-crowded, subregular, circular pores. Mouth about half as broad, constricted, with nine parallel, vertical, slender, conical feet, about as long as the cephalis.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.2 long, 0.18 broad.

Habitat.—Fossil in Barbados.

8. Anthocyrtis subglobosa, n. sp.

Shell spiny, with deep collar stricture. Length of the two joints = 1 : 7, breadth = 1 : 7. Cephalis subspherical, with a conical horn twice the length. Thorax nearly spherical, with small and very numerous, regular, circular pores. Mouth only one-third as broad, constricted, with nine parallel, vertical, square, lamellar feet, about twice as long as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.035 broad; thorax 0.2 long, 0.2 broad.

Habitat.—South Pacific, Station 297, depth 1775 fathoms.

Subgenus 3. Anthocyrtura, Haeckel.

Definition.—Feet of the peristome-corona convergent, their basal distance greater than their terminal distance.

9. Anthocyrtis enneaphylla, n. sp.

Shell smooth, with sharp collar stricture. Length of the two joints = 1 : 6, breadth = 1 : 5. Cephalis subspherical, with a conical horn twice the length, nearly hyaline, with very small and scarce pores. Thorax nearly spherical, with regular, circular, quincuncial pores. Mouth only half as broad, with nine broad, triangular feet, twice as long as the cephalis, and curved inwards, convergent towards the main axis.

Dimensions.—Cephalis 0.02 long, 0.025 broad; thorax 0.11 long, 0.12 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

10. Anthocyrtis ovata, n. sp. (Pl. 62, fig. 13).

Shell smooth, with slight collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 3. Cephalis ovate, with numerous small pores, and an excentric conical horn of the same length. Thorax ovate, with regular, circular, quincuncial pores. Mouth nearly of the same breadth, scarcely constricted, with nine triangular, widely-separated feet, about as long as the cephalis, and convergent towards the main axis.

Dimensions.—Cephalis 0.035 long, 0.03 broad; thorax 0.15 long, 0.1 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Genus 567. Anthocyrtium,^[72] n. gen.

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) without thoracic ribs, with numerous terminal feet around the mouth (twelve to fifteen or more). Cephalis free, with an apical horn.

The genus Anthocyrtium has been derived from the two preceding genera by further multiplication of the terminal feet, the number of which is at least twelve to fifteen, often twenty or more. It may be that some species have arisen directly from Patagospyris by loss of the sagittal ring.

Subgenus 1. Anthocyrtarium, Haeckel.

Definition.—Feet of the peristome-corona divergent, their basal distance less than their terminal distance.

1. Anthocyrtium chrysanthemum, n. sp. (Pl. 62, fig. 14).

Shell smooth, with distinct collar stricture. Length of the two joints = 3 : 7, breadth = 4 : 9. Cephalis hemispherical, with small, circular pores, and a large, straight, cylindro-conical horn, about as long as the shell. Thorax campanulate, hemispherical, with six to eight transverse rows of squarish pores, increasing in size downwards. Mouth little constricted, with twelve to fifteen divergent, curved, slender feet, about as long as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.07 long, 0.09 broad.

Habitat.—Central Pacific, Station 270 to 274, depth 2350 to 2925 fathoms.

2. Anthocyrtium centaurea, Haeckel.

Anthocyrtis mespilus, var. major, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. vi. fig. 5.

Shell smooth, with sharp collar stricture. Length of the two joints = 2 : 6, breadth = 3 : 7. Cephalis hemispherical, with irregular, roundish pores, and a very large pyramidal horn, longer than the shell, with contorted edges. Thorax hemispherical, with six to eight transverse rows of regular, circular pores of equal size. Mouth little constricted, with fifteen to twenty divergent, curved, slender feet, about as long as the shell.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.07 broad.

Habitat.—Fossil in Barbados.

3. Anthocyrtium anthemis, n. sp.

Shell papillate, with obliterated collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis hemispherical, with very small and scarce pores, and a conical horn of the same length. Thorax conical, as long as broad, with conical papillæ, and eight to ten transverse rows of roundish pores, gradually increasing in size downwards. Mouth scarcely constricted, with fifteen to twenty divergent, straight, conical feet, half as long as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.09 broad.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

4. Anthocyrtium collare, Haeckel.

Anthocyrtis collaris, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 64, Taf. vi. fig. 8.

Shell rough, conical, with obliterated collar stricture. Length of the two joints = 3 : 5, breadth = 4 : 7. Cephalis conical, with a pyramidal horn of the same length, and with two transverse rows of rather oblong, narrow pores. Thorax truncate, conical, in the lower part thorny, with six to eight transverse rows of regular, circular pores, increasing in size downwards.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.05 long, 0.07 broad.

Habitat.—Fossil in Barbados.

5. Anthocyrtium adonis, n. sp. (Pl. 62 fig. 20).

Shell rough, with sharp collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 12. Cephalis subspherical, with very small circular pores, and a very long, straight cylindrical, horn, twice to three times as long as the shell. Thorax inflated, ovate, or subspherical, with small regular, circular, hexagonally-framed pores. Mouth strongly constricted, half as broad as the thorax, with fifteen to twenty divergent, broad, lamellar, rectangular feet, as long as the thorax, and so densely placed that their margins come in contact with one another.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.12 broad.

Habitat.—Central Pacific, Station 263 to 268, depth 2650 to 3000 fathoms.

6. Anthocyrtium anemone, n. sp.

Shell spiny, with sharp collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 4. Cephalis subspherical, with a conical horn of half the length, hyaline, without pores. Thorax spiny, pear-shaped, inflated, with small and numerous, regular, circular pores. Mouth constricted, half as broad as the thorax, with twelve to fifteen divergent, slender, conical, denticulate feet, half as long as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.14 long, 0.12 broad.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms; also fossil in Barbados.

Subgenus 2. Anthocyrtonium, Haeckel.

Definition.—Feet of the peristome-corona parallel, vertical; their basal and apical distances equal.

7. Anthocyrtium campanula, n. sp. (Pl. 62, fig. 17).

Shell smooth, with deep collar stricture. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis spherical, with a conical horn of the same length. Thorax campanulate, thin-walled, with delicate network of regular, hexagonal pores and thin bars. Mouth little constricted, with twenty to twenty-four parallel, vertical, lanceolate feet, about as long as the cephalis.

Dimensions.—Cephalis 0.03 diameter, thorax 0.09 long, 0.1 broad.

Habitat.—South Pacific, Station 302, depth 1450 fathoms.

8. Anthocyrtium reticulatum, Haeckel.

Thyrsocyrtis reticulata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 10.

Shell rough, with sharp collar stricture. Length of the two joints = 1 : 2, breadth = 1 : 3. Cephalis hemispherical, with a prismatic, denticulate horn of the same length, and small, irregular pores. Thorax campanulate, thorny, thin-walled, with delicate network of irregular, polygonal pores. Mouth little constricted, with twelve (or more) small, parallel, vertical, triangular feet, shorter than the cephalis.

Dimensions.—Cephalis 0.015 long, 0.02 broad; thorax 0.04 long, 0.06 broad.

Habitat.—Fossil in Barbados.

9. Anthocyrtium leptostylum, Haeckel.

Anthocyrtis leptostyla, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 64, Taf. vi. fig. 1.

Shell thorny, with slight collar stricture. Length of the two joints = 1 : 5, breadth = 2 : 4. Cephalis hemispherical, with small, scarce pores and a slender conical horn of the same length. Thorax spiny, with regular, circular, quincuncial pores. Mouth constricted, half as broad, with twelve to eighteen slender, parallel, vertical feet, about as long as the cephalis.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.1 long, 0.08 broad.

Habitat.—Central Pacific, Stations 266 to 270, depth 2550 to 2925 fathoms; also fossil in Barbados.

10. Anthocyrtium hispidum, Haeckel.

Anthocyrtis hispida, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 64, Taf. viii. fig. 2. Anthocyrtis hispida, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 30.

Shell thorny, with sharp collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 5. Cephalis hemispherical, hyaline, with few very small pores, or without any; with a stout conical horn of twice the length. Thorax spiny, with regular, circular, hexagonally-framed pores (half as broad as the bars between them). Mouth wide open, scarcely constricted, with twelve to fifteen parallel, vertical, broad, lamellar, rectangular feet, reaching nearly the length of the thorax.

Dimensions.—Cephalis 0.02 to 0.03 long, 0.03 to 0.05 broad; thorax 0.07 to 0.09 long, 0.1 to 0.12 broad.

Habitat.—Central Pacific, Stations 263 to 265, depth 2650 to 3000 fathoms; also fossil in Barbados.

11. Anthocyrtium turris, n. sp.

Shell thorny, very similar to Calocyclas turris, Ehrenberg (1875, loc. cit., Taf. xviii. fig. 7), but without fenestrated abdomen. Collar stricture deep. Length of the two joints = 1 : 3, breadth = 1 : 3. Cephalis subspherical, hyaline, without pores, with a stout conical horn of twice the length. Thorax nearly spherical, spiny, with regular, circular, quincuncial pores. Mouth little constricted, with fifteen to twenty parallel, vertical, broad, lamellar, rectangular feet, about as long as the thorax.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.1 long, 0.1 broad.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

12. Anthocyrtium doronicum, n. sp. (Pl. 62, fig. 18).

Shell rough, with sharp collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 3. Cephalis hemispherical, with small, circular pores and a stout conical horn of twice the length. Thorax campanulate, subcylindrical, with regular, circular, quincuncial pores, three to four times as broad as the bars. Mouth scarcely constricted, with twenty-four to thirty vertical, nearly parallel, little curved feet, which are about half as long as the shell, broad, lamellar, rectangular, and in close contact with their edges.

Dimensions.—Cephalis 0.025 long, 0.035 broad, thorax 0.12 long, 0.1 broad.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

Subgenus 3. Anthocyrturium, Haeckel.

Definition.—Feet of the peristome-corona convergent, their basal distance greater than their apical distance.

13. Anthocyrtium pyrum, n. sp. (Pl. 62, fig. 12).

Shell smooth, with obliterated collar stricture. Length of the two joints = 2 : 7, breadth = 3 : 8. Cephalis hemispherical, with a small, bristle-shaped horn of half the length. Thorax inflated, subglobose, with regular, circular, quincuncial pores and thin bars. Mouth constricted, only half as broad, with fifteen to twenty small, triangular, convergent feet, shorter than the cephalis. (In another specimen the feet were twice as long, stronger and more convergent, than in the one figured.)

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.07 long, 0.8 broad.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

14. Anthocyrtium setosum, Haeckel.

Anthocyrtis setosa, Haeckel, 1862, Monogr. d. Radiol., p. 311. ? Lithopera setosa, Ehrenberg, 1854, Mikrogeol., Taf. xxxv. B., B. iv. fig. 23.

Shell spiny, with sharp collar stricture. Length of the two joints = 1 : 2, breadth = 1 : 3. Cephalis hemispherical, with a conical horn of the same length and some accessory spines. Thorax campanulate, with subregular, circular pores. Mouth little constricted, with twenty to thirty small, triangular, convergent feet, about as long as the cephalis. (In Ehrenberg's incomplete figure they are mostly broken off.)

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.04 long, 0.06 broad.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

15. Anthocyrtium ehrenbergii, Haeckel.

Anthocyrtis ehrenbergii, Stöhr, 1880, Palæontogr., vol. xxvi. p. 100, Taf. iii. fig. 21, a, b.

Shell smooth, with obliterated collar stricture. Length of the two joints = 3 : 10, breadth = 2 : 8. Cephalis subcylindrical, with an excentric, stout, pyramidal horn of the same length. Thorax bottle-shaped, with small, regular, circular pores of equal size. Mouth little constricted, with twenty to thirty small, triangular, convergent feet, about half as long as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.1 long, 0.08 broad.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte), Stöhr.

16. Anthocyrtium zanguebaricum, Haeckel.

Anthocyrtis zanguebarica, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 285, Taf. ix. fig. 12.

Shell smooth, with slight collar stricture. Length of the two joints = 3 : 10, breadth = 2 : 7. Cephalis subspherical, with an excentric conical horn of the same length. Thorax slender, ovate or bottle-shaped, with irregular, roundish pores increasing in size downwards. Mouth little constricted, with twelve to fifteen small, triangular, convergent feet, about half as long as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.1 long, 0.07 broad.

Habitat.—Indian Ocean (Zanzibar), depth 2200 fathoms, Pullen.

17. Anthocyrtium ficus, Haeckel.

Anthocyrtis ficus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 64, Taf. vi. fig. 3.

Shell rough, with obliterated collar stricture. Length of the two joints = 2 : 12, breadth = 3 : 10. Cephalis conical, with a large, cylindrical horn, pyramidal at the base, about as long as the thorax. Thorax subovate, truncate, papillate, with small, regular, circular, quincuncial pores of the same breadth as the bars. Mouth constricted, two-thirds as broad as the thorax, with fifteen to twenty strongly convergent, lamellar, rectangular or sword-shaped feet, nearly as long as the thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.12 long, 0.1 broad.

Habitat.—Fossil in Barbados.

18. Anthocyrtium flosculus, n. sp. (Pl. 62, fig. 19).

Anthocyrtis flosculus, Haeckel, 1881, Prodromus et Atlas, pl. lxii. fig. 19.

Shell ribbed, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 4. Cephalis hemispherical, with small, circular pores and a large cylindrical horn, twice as long as the thorax and half as broad at the base as the cephalis. Thorax subovate, truncate, with twenty-four to thirty longitudinal ribs and alternating rows of circular pores. Mouth constricted, two-thirds as broad as the thorax, with twenty-four to thirty slender, convergent feet, which are as long as the entire shell, with their edges in close contact and their distal ends pointed.

Dimensions.—Cephalis 0.03 long, 0.05 broad; thorax 0.12 long, 0.12 broad.

Habitat.—Central Pacific, Stations 265 to 274, depth 2350 to 2925 fathoms.

Genus 568. Anthocyrtidium,^[73] Haeckel, 1881, Prodromus, p. 431.

Definition.—Sethophormida, (vel Dicyrtida multiradiata aperta) without thoracic ribs, with numerous (twelve to fifteen or more) subterminal feet, which are separated from the constricted mouth by a ring of lattice-work. Cephalis free, with an apical horn.

The genus Anthocyrtidium has been derived from the preceding Anthocyrtium by further growth and constriction of the peristome, which becomes separated from the subterminal corona of feet by a more or less broad ring of lattice-work.

1. Anthocyrtidium cineraria, n. sp. (Pl. 62, fig. 16).

Shell campanulate, smooth, with obliterated collar stricture. Length of the two joints = 5 : 11, breadth = 3 : 13. Cephalis subcylindrical-ovate, with a conical straight horn of half the length. Thorax hemispherical, inflated, nearly twice as broad as the constricted mouth. Pores subregular, circular, double-contoured. Above the mouth, separated from it by two rows of pores, a corona of twelve to fifteen short conical feet, which are directed downwards, slightly curved, and as long as the cephalic horn.

Dimensions.—Cephalis 0.05 long, 0.03 broad; thorax 0.11 long, 0.13 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Anthocyrtidium ligularia, n. sp. (Pl. 62, fig. 15).

Shell campanulate, rough, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 6. Cephalis hemispherical, with a slender, conical, slightly curved horn, about as long as the shell. Thorax hemispherical, three times as broad as the cephalis, nearly twice as broad as the constricted mouth, which is prolonged into a prominent smooth ring. Above the mouth, separated from it by one row of pores, a corona of twelve to fifteen slender linear feet, which are slightly curved, divergent, and emarginate at the truncated distal end.

Dimensions.—Cephalis 0.015 long, 0.03 broad; thorax 0.06 long, 0.09 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Anthocyrtidium matricaria, n. sp.

Shell campanulate, rough, very similar to the preceding species, but differing in the straight, large, pyramidal horn of the cephalis (as long as the shell), and in the longer feet, which are twelve to fifteen in number, little curved at the distal end, pointed, and about as long as the shell. Length of the two joints = 2 : 6, breadth = 3 : 8. Differs from the similar Anthocyrtium centaurea, Ehrenberg (1875, loc. cit., Taf. vi. fig. 5), mainly in the prominent ring of the peristome.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.06 long, 0.08 broad.

Habitat.—Fossil in Barbados.

Genus 569. Carpocanium,^[74] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) without thoracic ribs, with numerous terminal feet around the mouth (six to twelve or more). Cephalis hidden in the thorax, without apical horn.

The genus Carpocanium, very common, and rich in numerous living and fossil species, was formerly placed by me among the true Monocyrtida, since an external constriction is not visible (Monogr., 1862, p. 290). Afterwards (in 1879) Richard Hertwig demonstrated that the cavity of the ovate shell, externally simple, is divided by an internal transverse septum into two joints, the upper of which is the flat rudimentary cephalis (Organism. d. Radiol., p. 79; compare also Bütschli, 1882, loc. cit., p. 535). Indeed this septum, with four central crossed cortinar beams, is a true collar septum, and Carpocanium has been derived from Anthocyrtis or Desmospyris by reduction of the cephalis, which is very flat and perfectly hidden in the uppermost part of the thorax. The apical horn is lost. If the internal septum were to become lost, the genus would pass over into Carpocanistrum.

Subgenus 1. Carpocanarium, Haeckel.

Definition.—Peristome-corona composed of six feet (three primary perradial alternating with three secondary interradial).

1. Carpocanium calycodes, Stöhr.

Carpocanium calycodes, Stöhr, 1880, Palæontogr., vol. xxvi. p. 96, Taf. iii. fig. 8.

Shell urceolate, smooth, nearly twice as long as broad, with hemispherical vaulted cephalis. Length of the two joints = 3 : 16, breadth = 5 : 10. Pores regular, circular, as broad as the bars, quincuncially disposed in about five longitudinal series at each side. Mouth constricted, half as broad as the thorax. Peristome with six vertical, equilateral, triangular feet.

Dimensions.—Cephalis 0.015 long, 0.025 broad; thorax 0.08 long, 0.05 broad.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte, Caltanisetta).

2. Carpocanium setosum, Haeckel.

Halicalyptra setosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 160, Taf. ii. fig. 12.

Shell ovate, truncate at the mouth, thorny, exactly as long as broad. Length of the two joints = 1 : 8, breadth = 3 : 9. Cephalis hidden, with very small pores. Thorax inflated, with regular, circular pores, twice as broad as the bars, in about ten longitudinal series at each side. Mouth constricted, half as broad as the thorax. Peristome with six vertical, parallel, broad, lamellar, rectangular feet, separated by equal internals, half as long as the shell.

Dimensions.—Cephalis 0.01 long, 0.03 broad; thorax 0.08 long, 0.09 broad.

Habitat.—Fossil in Barbados.

3. Carpocanium laeve, Ehrenberg.

Carpocanium laeve, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287.

Shell subspherical, smooth, equal in length and breadth, with little vaulted, cap-shaped cephalis. Length of the two joints = 1 : 6, breadth = 4 : 7. Pores regular, circular, twice as broad as the bars, in nine longitudinal rows. Mouth constricted, only one-third as broad as the thorax. Peristome with six strong conical feet, which are slightly curved and convergent.

Dimensions.—Cephalis 0.01 long, 0.04 broad; thorax 0.06 long, 0.07 broad.

Habitat.—Mediterranean (Greece); Tropical Atlantic, Station 348, depth 2450 fathoms.

4. Carpocanium lanceolatum, n. sp.

Shell subspherical, thorny, with perfectly hidden cephalis. Length of the two joints = 1 : 3, breadth = 1 : 3. Pores regular, circular, hexagonally framed, half as broad as the bars, in about sixteen longitudinal rows at each side. Mouth constricted, half as broad as the thorax. Peristome with six large lanceolate, vertical, lamellar feet, half as long as the shell.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.09 long, 0.09 broad.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

Subgenus 2. Carpocanidium, Haeckel.

Definition.—Peristome-corona composed of nine feet (three primary perradial and six secondary interradial).

{nop}} 5. Carpocanium diadema, Haeckel.

Carpocanium diadema, Haeckel, 1862, Monogr. d. Radiol., p. 290, Taf. v. fig. 1. Carpocanium diadema, R. Hertwig, 1879, Organism. d. Radiol., p. 79, Taf. viii. figs. 7, 7a, 8, 8a, 8b.

Shell ovate, with little vaulted cephalis. Length of the two joints = 1 : 8, breadth = 3 : 6. Pores regular, circular, in about twelve longitudinal rows, twice as broad as the bars. Mouth constricted, half as broad as the thorax. Peristome with nine vertical, equilateral, triangular feet.

Dimensions.—Cephalis 0.01 long, 0.03 broad; thorax 0.08 long, 0.06 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific; many stations, surface.

6. Carpocanium cylindricum, n. sp.

Shell cylindrical, with hemispherical, flatly vaulted cephalis. Length of the two joints = 1 : 4, breadth = 3 : 3. Pores regular, circular, double-contoured, as broad as the bars, in about fifteen longitudinal series. Mouth constricted, two-thirds as broad as the thorax. Peristome with nine vertical, slender, triangular, pointed feet.

Dimensions.—Cephalis 0.02 long, 0.06 broad; thorax 0.08 long, 0.06 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

7. Carpocanium enneaphyllum, n. sp.

Shell slenderly ovate, at the mouth truncate, thorny, with hemispherical, vaulted cephalis. Length of the two joints = 1 : 6, breadth = 2 : 4. Pores regular, circular, hexagonally framed, as broad as the bars, in about thirteen longitudinal rows. Mouth constricted, about two-thirds as broad as the thorax. Peristome with nine broad, lamellar, vertical, nearly square feet, half as long as the shell, with small intervals.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.12 long, 0.09 broad.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

8. Carpocanium solitarium, Ehrenberg.

Carpocanium solarium, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 28. Lithocampe solitaria, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 65.

Shell slenderly ovate, twice as long as broad, with hidden spherical cephalis, completely enclosed in the summit of the thorax. Length of the two joints = 1 : 6, breadth = 1 : 4. Pores small, regular, circular, as broad as the bars, in about eleven longitudinal rows. Mouth gradually constricted, half as broad as the thorax. Peristome with nine ovate blunt feet, which are as long as the cephalis, little curved and convergent.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.12 long, 0.07 broad.

Habitat.—Fossil in Tertiary rocks of Sicily (Caltanisetta).

9. Carpocanium gemmula, n. sp.

Shell subspherical, smooth, equal in length and breadth, with hemispherical vaulted cephalis. Length of the two joints = 2 : 7, breadth = 4 : 9. Pores small, regular, circular, twice as broad as the bars, in about twenty longitudinal rows. Mouth strongly constricted, only one-fourth as broad as the thorax. Peristome with nine conical feet, which are twice as long as the cephalis, curved, and so convergent that their distal ends come nearly in contact.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.07 long, 0.09 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

10. Carpocanium microdon, Ehrenberg.

Carpocanium microdon, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 30.

Shell broad, ovate, rough, with perfectly hidden cephalis. Length of the two joints = 2 : 9, breadth = 4 : 7. Pores very small and scarce, smaller than the bars between them, irregularly scattered. Mouth constricted, one-third as broad as the thorax. Peristome with nine short, triangular, pointed, convergent feet.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.09 long, 0.07 broad.

Habitat.—Mediterranean (Crete), Atlantic (Canary Islands), Station 354, surface.

Subgenus 3. Carpocanobium, Haeckel.

Definition.—Peristome-corona composed of twelve or more feet.

11. Carpocanium trepanium, n. sp. (Pl. 52, fig. 18).

Shell subcylindrical, with flatly vaulted cephalis. Length of the two joints = 1 : 6, breadth = 3 : 4. Pores regular, hexagonal, four to six times as broad as the bars. Mouth little constricted, two-thirds as broad as the thorax. Peristome with eighteen to twenty-four large, slender, triangular, vertical feet.

Dimensions.—Cephalis 0.02 long, 0.06 broad; thorax 0.12 long, 0.08 broad.

Habitat.—Indian Ocean, Madagascar (Rabbe), surface.

12. Carpocanium hexagonale, n. sp. (Pl. 52, fig. 15).

Shell broadly ovate or subconical, with vaulted, cap-shaped cephalis. Length of the two joints = 2 : 7, breadth = 6 : 9. Thorax subglobular, truncate. Pores subregular, hexagonal, three to four times as broad as the bars. Mouth constricted, two-thirds as broad as the thorax. Peristome with twenty to twenty-five small, triangular, vertical feet.

Dimensions.—Cephalis 0.02 long, 0.05 broad; thorax 0.07 long, 0.09 broad.

Habitat.—Tropical Atlantic, Station 347, surface.

13. Carpocanium petalospyris, n. sp. (Pl. 52, fig. 19).

Shell subspherical, smooth, with perfectly hidden cephalis. Length of the two joints = 1 : 6, breadth = 3 : 6. Pores regular, circular, hexagonally framed, twice as broad as the bars, in about sixteen longitudinal rows. Mouth slightly constricted, little narrower than the thorax. Peristome with twenty to twenty-four vertical, broad, lamellar feet, which are nearly as long as the shell, at the distal end truncate, and almost in contact at their edges.

Dimensions.—Cephalis 0.02 long, 0.05 broad; thorax 0.11 long, 0.12 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

14. Carpocanium polypterum, Haeckel.

Cryptoprora polyptera, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ix. fig. 17. Carpocanium macropterum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 302.

Shell campanulate-conical, smooth, with perfectly hidden cephalis. Length of the two joints = 1 : 6, breadth = 4 : 6. Pores regular, circular, twice as broad as the bars, in about sixteen longitudinal rows. Mouth wide open, not constricted. Peristome with twenty to thirty vertical, slender, conical feet, about as long as the shell.

Dimensions.—Cephalis 0.01 long, 0.04 broad; thorax 0.06 long, 0.06 broad.

Habitat.—Indian Ocean (Zanzibar), depth 2200 fathoms (Pullen).

15. Carpocanium palmipes, n. sp.

Shell ovate, very thick-walled, smooth. Lower half of the subspherical cephalis hidden in the summit of the thorax, upper half free, with few small pores. Length of the two joints = 3 : 10, breadth = 3 : 10. Thorax foveolate, with oblong dimples, each of which encloses a small, circular, double-contoured pore, half as broad as the bars. Mouth little constricted, nearly as broad as the thorax. Peristome prolonged into a solid, cylindrical tube, nearly as long and as broad as the shell; the upper half of the tube is solid, the lower divided into from twelve to fifteen vertical, lamellar, pointed feet.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.1 long, 0.1 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

16. Carpocanium peristomium, n. sp. (Pl. 52, figs. 16, 17).

Shell ovate, smooth, with perfectly hidden, flat cephalis (fig. 17). Length of the two joints = 2 : 10, breadth = 5 : 9. Pores small and very numerous, regular, circular, as broad as the bars, in about twenty longitudinal rows. Mouth little constricted. Peristome broad; in the upper half a hyaline, circular ring, in the lower half divided into from eighteen to twenty-four triangular, curved, little convergent feet.

Dimensions.—Cephalis 0.02 long, 0.05 broad; thorax 0.1 long, 0.09 broad.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific; many stations, at various depths.

17. Carpocanium coronatum, Ehrenberg.

Carpocanium coronatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. v. fig. 7.

Shell ovate, smooth, with perfectly hidden, subspherical cephalis. Length of the two joints = 2 : 9, breadth = 2 : 8. Pores small and very numerous, twice as broad as the bars, regular, circular, in about twenty longitudinal rows. Mouth little constricted, two-thirds as broad as the thorax. Peristome with twenty-five to thirty short, bristle-shaped feet, which are slightly curved, convergent, and in the upper half connected by a solid ring.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Fossil in Barbados.

18. Carpocanium dactylus, n. sp.

Shell slenderly ovate, twice as long as broad, with flat, perfectly hidden cephalis. Length of the two joints = 1 : 12, breadth = 4 : 8. Pores subregular, circular, as broad as the bars, in about twelve longitudinal rows, separated by prominent longitudinal ribs. Mouth constricted, two-thirds as broad as the thorax. Peristome with twelve large, lanceolate, lamellar, convergent feet.

Dimensions.—Cephalis 0.01 long, 0.04 broad; thorax 0.12 long, 0.08 broad.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

19. Carpocanium irregulare, n. sp. (Pl. 52, fig. 14).

Shell irregular, roundish, subovate, with flat and oblique, perfectly hidden cephalis. Length of the two joints = 1 : 10, breadth = 3 : 9. Pores irregularly scattered, roundish, about as broad as the bars. Mouth wide open, not at all or little constricted. Peristome with twenty to thirty long, lamellar, pointed feet, which are irregularly curved and convergent.

Dimensions.—Cephalis 0.01 to 0.02 long, 0.03 to 0.04 broad; thorax 0.09 to 0.11 long, 0.08 to 0.09 broad.

Habitat.—Central Pacific, Station 263 to 274, surface, and at various depths.

20. Carpocanium verecundum, n. sp. (Pl. 52, figs. 12, 13).

Shell ovate, smooth, with flat, perfectly hidden cephalis (fig. 12). Length of the two joints = 1 : 9, breadth = 4 : 9. Pores subregular, circular, twice as broad as the bars, in about eighteen, partly interrupted, longitudinal rows, separated by prominent crests. Mouth little constricted. Peristome with twenty to twenty-four broad, lamellar, pointed feet, which are about as long as the shell, little curved, and convergent.

Dimensions.—Cephalis 0.01 long, 0.04 broad; thorax 0.09 long, 0.09 broad.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

21. Carpocanium virgineum, n. sp. (Pl. 52, fig. 20).

Shell ovate, smooth, with flat perfectly hidden cephalis. Length of the two joints = 1 : 8, breadth = 3 : 9. Pores regular, circular, hexagonally framed, as broad as the bars, in about sixteen longitudinal rows on each side. Mouth little constricted. Peristome with eighteen to twenty-four very large, lamellar, pointed feet, which are longer than the shell, and so curved and convergent that their distal points come nearly in contact.

Dimensions.—Cephalis 0.01 long, 0.03 broad; thorax 0.08 long, 0.09 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Subfamily 2. Sethophænida, Haeckel, 1881, Prodromus, p. 433.

Definition.—Anthocyrtida with the basal mouth of the shell fenestrated (vel Dicyrtida multiradiata clausa).

Genus 570. Sethophæna,^[75] Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethophænida (vel Dicyrtida multiradiata clausa) with lateral apophyses. Cephalis with a horn.

The genus Sethophæna and the following Clistophæna form together the small subfamily of Sethophænida, comprising those Dicyrtida in which the thorax bears numerous radial appendages (four to six or more), and the mouth is closed by a lattice-plate. In Sethophæna the apophyses are lateral wings, as in Micromelissa, from which it may be derived by development of secondary wings, interpolated between the three primary wings.

1. Sethophæna tetraptera, n. sp.

Shell smooth, with deep collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 9. Cephalis subspherical, without horn. Thorax ovate, with rounded hemispherical base, and subregular, hexagonal pores. From its upper half (below the collar stricture) arise four divergent, conical, straight wings, of half the length, opposite in pairs in two meridional planes, perpendicular to one another (compare Tetralacorys, Pl. 65, figs. 4, 5).

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.09 broad.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

2. Sethophæna hexaptera, n. sp. (Pl. 97, fig. 13).

Shell rough, pear-shaped, with distinct collar stricture. Length of the two joints = 1 : 4, breadth = 2 : 4. Cephalis hemispherical, with a conical horn of the same length. Thorax inflate, inversely ovate, nearly pear-shaped, with subregular, circular pores. From its upper half arise, by a broad base, six divergent, strong, conical wings, which are horn-like, curved downwards, and half as long as the thorax.

Dimensions.—Cephalis 0.025 long, 0.04 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Sethophæna enneaptera, n. sp.

Shell rough, with sharp collar stricture. Length of the two joints = 1 : 6, breadth = 1 : 3. Cephalis subspherical, with a stout conical horn of twice the length. Thorax inversely ovate, with pointed, conical, basal part, and irregular, roundish pores. From its middle part arise, by a broad triangular base, nine compressed, divergent wings, which are a little curved, slender, and about as long as the thorax.

Dimensions.—Cephalis 0.025 long, 0.03 broad; thorax 0.17 long, 0.1 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

4. Sethophæna polyptera, n. sp.

Shell thorny, with slight collar stricture. Length of the two joints = 1 : 10, breadth = 3 : 8. Cephalis flat, cap-shaped, without horn. Thorax pear-shaped, with hemispherical base and regular, circular pores. From its lower half (beyond the equator) arises a corona of numerous short conical wings (eighteen to twenty-four), which are a little curved, and divergent downwards, scarcely one-third as long as the thorax.

Dimensions.—Cephalis 0.015 long, 0.04 broad; thorax 0.15 long, 0.12 broad.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

Genus 571. Clistophæna,^[76] Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethophænida (vel Dicyrtida multiradiata clausa) with terminal apophyses. Cephalis with a horn.

The genus Clistophæna agrees with the preceding Sethophæna in the mouth of the thorax being closed by a lattice-plate. But the appendages of the thorax are terminal feet, not lateral wings; their number is commonly six or nine, rarely more. Clistophæna may be derived either from Tetrahedrina by interpolation of secondary feet between the three primary, or from Sethamphora by development of a basal lattice-plate closing the mouth.

1. Clistophæna rüstiana, n. sp. (Pl. 57, fig. 6).

Shell rough, with distinct collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 11. Cephalis hemispherical, with small, circular pores and a stout oblique horn three times the length, which is three-sided prismatic, and at the top denticulate. Thorax subconical, inflate, with regular, circular, quincuncial pores, increasing in size towards the base. Margin of the flat base, with six divergent, stout feet of the same prismatic form as the cephalic horn, with denticulate distal ends, about as long as the thorax. This elegant species is dedicated to Dr. Rüst of Freiburg, the discoverer of numerous fossil Radiolaria in the Liassic and Jurassic formations.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.11 broad.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Clistophæna hexolena, n. sp.

Shell smooth, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 5. Cephalis subspherical, small, with a large, vertical, cylindrical horn, about as long as the shell, and small, circular pores. Thorax nearly three-sided pyramidal or tetrahedral, with three rounded edges and sub-regular, circular pores. Margin of the flat base with six conical, divergent, straight feet, somewhat shorter than the thorax. (Three on the corners, one on the middle of each side of the triangular base.)

Dimensions.—Cephalis 0.03 diameter, thorax 0.12 long, 0.14 broad.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

3. Clistophæna pyramidalis, n. sp.

Shell smooth, with slight collar stricture. Length of the two joints = 2 : 8, breadth = 3 : 10. Cephalis hemispherical, with a stout pyramidal horn of twice the length. Thorax six-sided pyramidal, with regular, circular pores of equal size, and six prominent, straight edges, which are prolonged into six divergent, pyramidal feet of half the length.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.1 broad.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

4. Clistophæna armata, n. sp. (Pl. 57, fig. 7).

Shell spiny, with deep collar stricture. Length of the two joints = 4 : 18, breadth = 5 : 15. Cephalis subspherical, with small, circular, hexagonally-framed pores, and a stout, three-sided prismatic, cuspidate horn of the same length. Thorax pear-shaped, with regular, circular pores and three pairs of stout pyramidal wings, placed in the three primary meridional planes of the collar beams; three of them lie in the upper, and three in the lower third of the thorax. Margin of the flat base with nine cylindrical, somewhat club-shaped, divergent feet.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.18 long, 0.15 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

5. Clistophæna enneolena, n. sp.

Shell spiny, with sharp collar stricture. Length of the two joints = 4 : 20, breadth 5 : 16. Cephalis hemispherical, hyaline, with a stout conical horn of the same length and some small accessory horns. Thorax ovate, spiny, with subregular, circular pores. Margin of the vaulted base with nine divergent, conical feet, half as long as the thorax.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.2 long, 0.16 broad.

Habitat.—South Pacific, Station 296, depth 1825 fathoms.

6. Clistophæna polyolena, n. sp.

Shell smooth, conical, with obliterated collar stricture. Length of the two joints = 1 : 5, breadth = 2 : 5. Cephalis hemispherical, with small, circular pores and two divergent conical horns (a major occipital and a smaller frontal horn). Thorax obtusely conical, with regular, hexagonal pores at the mantle, and circular pores in the basal plate, the margin of which bears eighteen vertical, parallel, conical feet, as long as the cephalis.

Dimensions.—Cephalis 0.015 long, 0.025 broad; thorax 0.08 long, 0.08 broad.

Habitat.—Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

Family LXIV.—Sethocyrtida, n. fam.

Sethocorida et Sethocapsida, Haeckel, 1881, Prodromus, pp. 439, 433.

Definition.—Dicyrtida eradiata. (Cyrtoidea with a two-jointed shell, divided by a transverse constriction into cephalis and thorax, without radial apophyses).

The family Sethocyrtida, composed of the Sethocorida and Sethocapsida of my Prodromus, comprises those Cyrtoidea in which the shell is two-jointed and bears no radial apophyses. The two subfamilies differ in the shape of the mouth, which in the Sethocorida is a simple wide opening, and in the Sethocapsida is closed by a lattice-plate. The former are here divided into eight, the latter into three genera.

Numerous living and fossil forms of Sethocyrtida were previously described by Ehrenberg, partly in his genera Dictyocephalus and Lophophæna, partly (intermingled with three-jointed and many-jointed forms) in the genera Eucyrtidium and Lithocampe. A larger number of new forms has been found in the Radiolarian ooze collected by the Challenger, and others fossil in Barbados. Many of these Sethocyrtida are common and widely distributed. When a new third joint is formed on their basal mouth, they pass over into Theocyrtida.

The cephalis is usually subspherical or hemispherical, and much smaller than the thorax, the form of which exhibits all possible intermediate stages between flat, discoidal, conical, cylindrical, and ovate forms. The wide open mouth becomes more and more constricted, and finally closed in the Sethocapsida. The majority of the Sethocyrtida may have been derived either from the Tripocyrtida, or from the Anthocyrtida by reduction and loss of the radial apophyses.

Synopsis of the Genera of Sethocyrtida.

I. Subfamily Sethocorida. Terminal mouth of the thorax a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Thorax conical or campanulate, gradually dilated.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Shell simple, without mantle,			572. Sethoconus.
				Shell double, with an arachnoid mantle,			573. Periarachnium.
		Thorax discoidal, flatly expanded.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Cephalis very large, without horn,			574. Sethocephalus.
		Thorax cylindrical or ovate, with truncate, constricted or tubular mouth.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Cephalis with a single horn.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth simple,	575. Sethocyrtis.
						Mouth tubular,	576. Sethocorys.
				Cephalis with two horns or a bunch of horns,			577. Lophophæna.
				Cephalis without horn,			578. Dictyocephalus.
II. Subfamily Sethocapsida. Terminal mouth closed by a lattice-plate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Cephalis free, not hidden in the thorax.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	One horn,			579. Sethocapsa.
				No horn,			580. Dicolocapsa.
		Cephalis hidden in the upper part of the thorax.		No horn,			581. Cryptocapsa.

Subfamily 1. Sethocorida, Haeckel, Prodromus, p. 430.

Definition.—Sethocyrtida with the basal mouth of the shell open (vel Dicyrtida eradiata aperta).

Genus 572. Sethoconus,^[77] Haeckel, 1881, Prodromus, p. 430.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with conical or campanulate, gradually dilated thorax and wide open mouth. Cephalis with one or more horns.

The genus Sethoconus is the oldest and simplest form of the Sethocorida, or of those Dicyrtida in which the simple thorax bears no apophyses and has the mouth open and not closed by a basal lattice-plate. Probably all those eradiate Sethocorida have been derived either from triradiate Sethopilida (Lychnocanium), or from multiradiate Sethophormida (Sethophormis, Anthocyrtis ?) by loss of the radial ribs and feet. In Sethoconus the thorax is more or less conical, sometimes more campanulate, commonly smooth, in some species covered with spines. The cephalis is usually small, with rudimentary collar septum, at other times large, with distinct cortinar septum. Correspondingly, the genus may be divided into different groups, which here are enumerated as subgenera.

Subgenus 1. Conarachnium, Haeckel, 1881, Prodromus, p. 430. (= Ceratocyrtis, Bütschli), 1882, loc. cit., p. 536.

Definition.—Cephalis relatively large, with distinct collar septum and numerous pores. Thorax smooth.

1. Sethoconus trochus, Haeckel.

Eucyrtidium trochus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii, fig. 17. Conarachnium trochus, Haeckel, 1881, Prodromus, p. 430.

Cephalis ovate, relatively large, with a pyramidal horn of the same length, and three pairs of large opposite pores, on each side of a vertical septum. Thorax wide, conical, about as long as broad, with nearly straight outlines; its pores regular, circular, hexagonally framed, of the same size as the cephalic pores.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.06 long, 0.06 broad.

Habitat.—Tropical Pacific, Stations 200 to 281, surface.

2. Sethoconus cucullaris, Haeckel.

Cornutella cucullaris, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 7. Ceratocyrtis cucullaris, Bütschli, 1882, Zeitschr. f. wiss Zool., Bd. xxvi. p. 536, Taf. xxxiii. fig. 36, a., b.

Cephalis subspherical, thorny, relatively large, with a conical horn of the same length, and small circular pores. Thorax wide, conical, enveloping the lower hidden half of the cephalis, about as long as broad, with slightly convex outlines; its pores subregular, circular, half as broad as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.15 long, 0.14 broad.

Habitat.—Fossil in Barbados.

3. Sethoconus pileus, n. sp.

Cephalis subspherical, free, with distinct collar stricture, a conical oblique horn of the same length, and small, irregular, roundish pores. Thorax flatly conical, about half as long as broad, with straight outlines; its pores subregular, hexagonal, half as broad as the cephalis, with very thin bars.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.08 long, 0.16 broad.

Habitat.—Central Pacific, Stations 262 to 274, surface.

4. Sethoconus ampliatus, Haeckel.

Cornutella ampliata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 5. Ceratocyrtis ampliata, Bütschli, 1882, Zeitschr. f. wiss. Zool., Bd. xxxvi. p. 536.

Cephalis, hemispherical, thorny, with a conical horn of twice the length; it is separated from the thorax by a complete internal collar septum, but without external collar stricture. Thorax flatly conical, about half as long as broad, with straight outlines; its pores subregular, hexagonal, about as large as the cephalis, with thin bars.

Dimensions.—Cephalis 0.015 long, 0.03 broad; thorax 0.08 long, 0.18 broad.

Habitat.—Fossil in Barbados.

5. Sethoconus mitra, Haeckel.

Cornutella mitra, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 8. Ceratocyrtis mitra, Bütschli, 1882, Zeitschr. f. wiss. Zool., Bd. xxxvi. p. 536.

Cephalis ovate, with slight collar stricture (not distinct enough in Ehrenberg's figure), with few large pores, and a conical stout horn of the same length. Thorax campanulate, conical, twice as long as broad, with slightly convex outlines; its pores subregular, roundish, increasing in size towards the mouth, the largest as broad as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.12 long, 0.07 broad.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms; fossil in Barbados.

6. Sethoconus rayianus, n. sp. (Pl. 58, fig. 6).

Conarachnium rayianum, Haeckel, 1881, Prodromus, p. 430.

Cephalis ovate, with obliterated collar stricture (but distinct internal septum), with small, irregular pores, and two to four divergent horns, which are longer than the cephalis, and two or three of which are forked. Thorax tent-shaped, conical, two-thirds as long as broad, with slightly concave outlines, and subregular, hexagonal pores, gradually increasing towards the mouth, the largest half as broad as the cephalis. This elegant species is dedicated to Dr. Ray, the discoverer of many rare Radiolarians in the Challenger collection.

Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax 0.08 long, 0.12 broad.

Habitat.—Central Pacific, Stations 266 to 272, surface.

7. Sethoconus cervus, Haeckel.

? Eucyrtidium cervus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ix. fig. 21. Conarachnium cervus, Haeckel, 1881, Prodromus, p. 430.

Cephalis subspherical, with slight collar stricture, small circular pores, and two to four divergent horns, one or two of which are forked. Thorax wide, conical, about as long as broad, with straight outlines and irregular, polygonal pores, gradually increasing towards the mouth; the largest as broad as the cephalis.

Dimensions.—Cephalis 0.015 long, 0.02 broad; thorax 0.08 long, 0.08 broad.

Habitat.—Indian Ocean; Maldive Islands, surface (Haeckel); Zanzibar, depth 2200 fathoms (Pullen).

8. Sethoconus lophophæna, n. sp.

Conarachnium lophophæna, Haeckel, 1881, Prodromus, p. 430.

Cephalis subspherical, with distinct collar stricture, small circular pores, and numerous (twelve to sixteen) radial, bristle-shaped horns of different lengths. Thorax wide, conical, somewhat longer than broad, with slightly convex outlines, and subregular, hexagonal pores, increasing gradually in size towards the mouth; the largest twice as broad as the cephalis.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.2 long, 0.16 broad.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

9. Sethoconus larvatus, Haeckel.

Lophophæna larvata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 10. Dictyocephalus larvatus, Bütschli, 1882, Zeitschr. f. wiss. Zool., Bd. xxxvi. p. 535.

Cephalis subspherical, large, with sharp collar stricture, and numerous (five to ten or more) radial, conical (partly forked) horns of different lengths. Thorax wide, conical, somewhat broader than long, with straight outlines. Pores of both joints very irregular, roundish, of very different sizes and form.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.1 long, 0.12 broad.

Habitat.—Fossil in Barbados.

10. Sethoconus nassa, Haeckel.

Eucyrtidium nassa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 9.

Cephalis slenderly ovate, with sharp collar stricture, few scattered pores, and a very stout, pyramidal horn of the same length, which is surrounded at the base by three short, divergent, ascending spines (perhaps the remnants of the three cortinar rods of Eucecryphalus, &c. ?). Thorax slender, conical, with straight outlines, and small, dense, regular, circular pores of equal size.

Dimensions.—Cephalis 0.04 long, 0.02 broad; thorax 0.12 long, 0.08 broad.

Habitat.—Fossil in Barbados.

11. Sethoconus tabulatus, Haeckel.

Cycladophora tabulata, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 289, Taf. iv. fig. 18.

Cephalis subspherical, with slight collar stricture, and numerous small, irregular pores, without horn, or with a small conical horn. Thorax slenderly conical, with straight outlines, and large, regular, hexagonal pores. Mouth truncate. (In the specimen I examined the thorax was longer and more conically dilated; the cephalis had a distinct small horn.)

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.06 broad.

Habitat.—North Atlantic, Antilles, depth 1600 fathoms (Ehrenberg); Station 347, depth 2250 fathoms.

Subgenus 2. Cornutellium (vel Ceratarachnium), Haeckel, 1881, Prodromus, p. 430.

Definition.—Cephalis very small, rudimentary, hyaline, without distinct collar septum, and without pores (or with scarce, rudimentary pores). Thorax smooth.

12. Sethoconus hexagonalis, Haeckel.

Cornutella trochus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ix. fig. 14.

Cephalis very small, subspherical, hyaline, without pores, with a rudimentary horn of half the length. Thorax slenderly conical, or bottle-shaped, twice to three times as long as broad; in the lower half nearly cylindrical, with very thin, thread-like bars, and regular, hexagonal pores, increasing in size towards the mouth.

Dimensions.—Cephalis 0.005 diameter, thorax 0.12 long, 0.05 broad.

Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).

13. Sethoconus verrucosus, Haeckel.

Cornutella verrucosa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ix. fig. 16.

Cephalis very small, subspherical, hyaline, without pores, with a rudimentary horn of half the length. Thorax slenderly conical, or bottle-shaped, with little convex outlines; three to four times as long as broad, papillate, with regular, circular pores, which are included by rhombic frames, and increase in size towards the mouth.

Dimensions.—Cephalis 0.004 diameter, thorax 0.12 long, 0.035 broad.

Habitat.—Indian Ocean (Zanzibar), depth 2200 fathoms (Pullen).

14. Sethoconus orthoceras, n. sp. (Pl. 54, fig. 11).

Cornutella orthoceras, Haeckel, 1879, Atlas, loc. cit.

Cephalis very small, conical, hyaline, without pores, with a double internal stricture, and a very short, rudimentary horn. Thorax slenderly conical, with undulate outlines, three to four times as long as broad, with subregular, roundish pores, gradually increasing in size towards the mouth.

Dimensions.—Cephalis 0.02 long, 0.01 broad; thorax 0.16 long, 0.04 to 0.08 broad.

Habitat.—South Atlantic, Station 325, surface.

15. Sethoconus profundus, Haeckel.

Cornutella profunda, Ehrenberg, 1854, Mikrogeol., Taf. xxxv. B, Nr. B. iv. fig. 21.

Cornutella profunda, Bailey, 1856, Amer. Jour., vol. xxii. pl. i. fig. 23.

Cornutella profunda, Haeckel, 1862 Monogr. d. Radiol., p. 284.

Cephalis very small, spherical, hyaline without pores and internal stricture, with a very short, rudimentary horn. Thorax slenderly conical with straight outlines, three to four times as long as broad, with subregular, circular pores, gradually increasing in size towards the mouth.

Dimensions.—Cephalis 0.004 to 0.008 diameter, thorax 0.08 to 0.12 long, 0.03 to 0.04 broad.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific; at various depths.

16. Sethoconus trichostylus, Haeckel.

Cornutella trichostyla, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. vi. fig. 2.

Cephalis very small, conical, hyaline, without pores, with a very long, bristle-shaped, spirally twisted horn, longer than the whole shell. Thorax slenderly conical, with straight outlines, and very small, regular, circular pores of nearly equal size, which are separated by broader bars and spirally ascending oblique crests (according to the figure).

Dimensions.—Cephalis 0.004 long, 0.002 broad; thorax 0.06 long, 0.04 broad.

Habitat.—North Pacific (California), depth 2600 fathoms.

17. Sethoconus longisetus, Haeckel.

Cornutella longiseta, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ix. fig. 15.

Cephalis very small, spherical, hyaline, without pores, with a very long, bristle-shaped horn, nearly as long as the shell. Thorax slenderly conical, rough, with straight outlines, and irregular, roundish pores, gradually increasing in size towards the mouth.

Dimensions.—Cephalis 0.01 diameter, thorax 0.09 long, 0.03 broad.

Habitat.—Indian Ocean (Zanzibar), depth 2200 fathoms (Pullen).

18. Sethoconus gracilis, Haeckel.

Eucyrtidium gracile, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 15.

Cephalis small, subspherical, with few scarce pores, and a stout, pyramidal horn, of the same length. Thorax slenderly conical, three to four times as long as broad, with straight outlines, and very small and numerous circular pores of equal size.

Dimensions.—Cephalis 0.015 diameter, thorax 0.12 long, 0.04 broad.

Habitat.—Fossil in Barbados.

19. Sethoconus bimarginatus, n. sp. (Pl. 54, fig. 12).

Cornutella bimarginata, Haeckel, 1879, Atlas, loc. cit.

Cephalis very small, subspherical, hyaline, without pores, with a rudimentary, conical horn of the same length. Thorax slenderly conical, three times as long as broad, with undulated, little convex outlines, and irregular, roundish, double-contoured pores, arranged in nine longitudinal series, markedly increasing in size towards the mouth.

Dimensions.—Cephalis 0.01 diameter, thorax 0.16 long, 0.05 broad.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

20. Sethoconus clathratus, Haeckel.

Cornutella clathrata, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 39a, b, c.

Cephalis very small, subspherical, hyaline, without pores, with a rudimentary horn of half the length. Thorax slenderly conical, three to four times as long as broad, smooth, with curved axis and small, regular, circular pores, nearly equal in size. This common species differs from all others of the genus by the curvation of the axis of the shell, which is more or less crescentic, or curved like a cowherd's horn; it may, therefore, represent a peculiar genus, Sethodrepanum.

Dimensions.—Cephalis 0.003 to 0.006 diameter, thorax 0.08 to 0.16 long, 0.03 to 0.05 broad.

Habitat.—Cosmopolitan; Atlantic, Pacific, many stations; fossil in Barbados and Sicily.

Subgenus 3. Phlebarachnium, Haeckel (et Cladarachnium, Haeckel), 1881,

Prodromus, p. 430.

Definition.—Cephalis small, with very small pores, and internal collar septum. Thorax spiny or thorny.

21. Sethoconus facetus, n. sp. (Pl. 55, fig. 1).

Phlebarachnium facetum, Haeckel, 1881, Prodromus, p. 430.

Cephalis small, hemispherical, with distinct collar septum, the same network as the thorax, and numerous bristle-shaped horns of the same length. Thorax wide, conical, about as long as broad, with slightly convex outlines; its network extremity delicate, with very small and numerous, regular, hexagonal pores, disposed in numerous divergent, longitudinal series, which are convoluted somewhat spirally around the shell axis. Surface covered with thin, scattered, bristle-shaped spines, about as long as the cephalis.

Dimensions.—Cephalis 0.02 diameter, thorax 0.2 long, 0.22 broad.

Habitat.—Central Pacific, Stations 271 to 274, surface.

22. Sethoconus anthocyrtis, n. sp. (Pl. 62, fig. 21).

Anthocyrtis sethoconus, Haeckel, 1879, Atlas, loc. cit.

Cephalis small, subspherical, with very small pores and numerous radial, bristle-shaped spines of the same length. Thorax wide, conical, about as long as broad, with parabolic outlines, its network very delicate, with subregular, hexagonal meshes. Surface with scarce, bristle-shaped spines (not represented in the figure). Mouth with a corona of numerous small, vertical spines.

Dimensions.—Cephalis 0.025 diameter, thorax 0.26 long, 0.24 broad.

Habitat.—North Pacific, Station 248, surface.

23. Sethoconus virgultus, n. sp.

Cladarachnium virgultum, Haeckel, 1881, Prodromus, p. 430.

Cephalis and thorax nearly of the same form and stricture as in Sethoconus facetus, but larger and wider, with the same delicate, hexagonal network (Pl. 55, fig. 1); it differs from the latter by the wider, more convex and campanulate form, but mainly by the armature of the surface, which is densely covered with thin, arborescent, bristle-shaped spines, irregularly branched, and four to eight times as large as the cephalis.

Dimensions.—Cephalis 0.02 diameter, thorax 0.32 long, 0.4 broad.

Habitat.—South Pacific, Station 288, surface.

24. Sethoconus setosus, n. sp.

Phlebarachnium setosum, Haeckel, 1881, Prodromus, p. 430.

Cephalis small, subspherical, with distinct collar septum, and the same network as the thorax, with numerous bristle-shaped horns of the same length. Thorax slenderly conical, twice as long as broad, with irregular, polygonal pores of little different sizes, and very thin bars. Surface covered with perpendicular, simple, bristle-shaped spines, about as long as the cephalis.

Dimensions.—Cephalis 0.02 diameter, thorax 0.12 long, 0.22 broad.

Habitat.—Central Pacific, Stations 266 to 272, surface.

25. Sethoconus venosus, n. sp. (Pl. 55, fig. 2).

Phlebarachnium venosum, Haeckel, 1881, Prodromus, p. 430, et Atlas, loc. cit.

Cephalis subspherical, with a stout prismatic horn twice the length, bearing three denticulate edges. The uppermost part of the thorax is supported by three diverging, radial beams arising from the deep collar stricture. Thorax wide, conical, nearly twice as long as broad, with slightly convex, thorny outlines; its delicate network is composed of very irregular, polygonal meshes of different sizes, separated by stronger bars, and of numerous very small polygonal pores separated by very thin bars inside the former. The central capsule of the figured specimen exhibited in the upper third of the thorax four large club-shaped lobes, which arose from a very small sphere enclosed in the cephalis and containing the nucleus.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.4 long, 0.3 broad.

Habitat.—Central Pacific, Station 271, surface.

Genus 573. Periarachnium,^[78] Haeckel, 1881, Prodromus, p. 430.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with conical or campanulate, gradually dilated thorax, and widely open mouth. Primary lattice-shell enveloped by an external arachnoidal mantle. Cephalis with one or more horns.

The genus Periarachnium has been derived from those forms of the preceding Sethoconus, in which the conical thorax is covered with simple spines (Phlebarachnium) or branched spines (Cladarachnium). By communication of the branches of these spines a second outer shell is formed, which, like an arachnoidal mantle, envelops the inner primary shell.

1. Periarachnium periplectum, n. sp. (Pl. 55, fig. 11).

Cephalis hemispherical, separated from the thorax by a sharp collar stricture, from which arise three internal, diverging beams supporting its upper third. Thorax campanulate, conical, about as long as broad, with slightly convex outlines. The delicate lattice-work of the entire shell is double; the inner composed of subregular, hexagonal meshes; the outer of larger, irregular, polygonal meshes. The bars of the inner are much thicker than the thin threads of the outer. Both shells are connected by numerous bristle-shaped beams. The central capsule of the figured specimen exhibited in the upper part of the thorax three club-shaped lobes, which arose from a sphere enclosed in the cephalis and containing the nucleus.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.15 long, 0.12 broad.

Habitat.—Central Pacific, Station 271, surface.

Genus 574. Sethocephalus,^[79] Haeckel, 1881, Prodromus, p. 430.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with discoidal, flatly expanded thorax. Cephalis large, without horn.

The genus Sethocephalus (formerly proposed under the name Platycryphalus) contains some few and rare Sethocorida, distinguished by the very large cephalis, the collar opening of which is wide open, not closed by cortinar beams, and surrounded by a very flat, nearly discoidal thorax, like the brim of a hat. It is possible that this peculiar genus has been derived from a Tricyrtid (Theocalyptra?) by loss of the original cephalis, and that the apparent large cephalis is the original thorax.

1. Sethocephalus eucecryphalus, n. sp. (Pl. 56, fig. 13).

Cephalis very large, campanulate-conical, with irregular, polygonal pores and thin bars. Thorax short, scarcely broader than the cephalis, beyond the sharp collar stricture expanded like the brim of a hat, with few rows of irregular, polygonal pores. (In the specimen figured the thorax was only half as broad as in another specimen found afterwards.)

Dimensions.—Cephalis 0.12 long, 0.09 broad; thorax 0.02 long, 0.12 broad.

Habitat.—South Pacific, Station 285, surface.

2. Sethocephalus platycryphalus, n. sp.

Platycryphalus sethodiscus, Haeckel, 1881, Prodromus, p. 430.

Cephalis large, hemispherical, with irregular square pores and thin bars. Thorax flatly conical, three to four times as broad as the cephalis, beyond the collar stricture expanded nearly discoidally, with a delicate network of small, subregular, hexagonal pores. (Similar in general form to Sethophormis aurelia, Pl. 55, fig. 3, but without any trace of collar beams or radial ribs.)

Dimensions.—Cephalis 0.04 long, 0.08 broad; thorax 0.04 long, 0.3 broad.

Habitat.—South Pacific, Station 289, surface.

Genus 575. Sethocyrtis,^[80] n. gen.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with ovate or subcylindrical thorax, the mouth of which is constricted, simple, without prominent hyaline peristome. Cephalis with an apical horn.

The genus Sethocyrtis and the three following nearly allied genera differ from the three preceding genera of Sethocorida in the form of the thorax, which is not gradually dilated, conical, but cylindrical or ovate, with more or less constricted mouth. Sethocyrtis may be derived from Anthocyrtis by loss of the terminal feet. Its mouth is quite simple, without tubular or annular peristome.

1. Sethocyrtis oxycephalis, n. sp. (Pl. 62, fig. 9).

Shell rough, subconical, with slight collar stricture. Length of the two joints = 4 : 9, breadth = 3 : 8. Cephalis ovate, with a pyramidal horn of half the length. Thorax campanulate, with regular, circular pores, twice as broad as those of the cephalis. Mouth constricted, scarcely half as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 3000 fathoms.

2. Sethocyrtis cancrina, Haeckel.

Eucyrtidium cancrinum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 4.

Shell smooth, bottle-shaped, with obliterated collar stricture. Length of the two joints = 4 : 9, breadth = 2 : 7. Cephalis subcylindrical, with a stout conical horn of the same length, and sometimes a smaller accessory horn at its base. Thorax ovate, truncate, with regular, circular, quincuncial pores, twice as broad as those of the cephalis. Mouth little constricted, flat, nearly as broad as the thorax.

Dimensions.—Cephalis 0.04 long, 0.02 broad; thorax 0.09 long, 0.07 broad.

Habitat.—Fossil in Barbados.

3. Sethocyrtis diomedis, n. sp.

Shell thorny, pear-shaped, with slight collar stricture. Length of the two joints = 3 : 16, breadth = 4 : 20. Cephalis hemispherical, with a conical horn of twice the length. Thorax inflate, ovate, truncate at both poles, with regular, circular pores, twice as broad as those of the thorax. Mouth constricted, flat, half as broad as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.12 to 0.16 long, 0.16 to 0.2 broad.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; also fossil in Barbados.

4. Sethocyrtis menelai, n. sp.

Shell spiny, pear-shaped, with sharp collar stricture. Length of the two joints = 3 : 15, breadth = 4 : 18. Cephalis subspherical, with a large, cylindro-conical horn, about as long as the whole shell. Thorax inflate, subspherical, truncate, with large, irregular, roundish pores, four to six times as large as those of the cephalis. Mouth constricted, flat, one-third as broad as the thorax.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.15 long, 0.18 broad.

Habitat.—Fossil in Barbados.

5. Sethocyrtis subacuta, Haeckel.

Eucyrtidium subacutum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 18.

Shell smooth, pear-shaped, with sharp collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 3. Cephalis subspherical, with small, irregular pores and a rudimentary horn of half the length. Thorax ovate, with large, subregular, hexagonal pores and thin bars between them. Mouth constricted, flat, half as broad as the thorax, without prominent peristome.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.08 long, 0.06 broad.

Habitat.—Philippine Sea, depth 3300 fathoms (Ehrenberg).

6. Sethocyrtis pleuracantha, Haeckel.

Eucyrtidium pleuracanthum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 21.

Shell smooth, bottle-shaped, with distinct collar stricture. Length of the two joints = 2 : 4, breadth = 1 : 3. Cephalis slenderly ovate, with an excentric pyramidal horn of the same length. Thorax inflate, ovate, with irregular, roundish pores and thin bars between them. Mouth constricted, flat, half as broad as the thorax, without prominent peristome.

Dimensions.—Cephalis 0.04 long, 0.02 broad; thorax 0.08 long, 0.06 broad.

Habitat.—Tropical Pacific, Stations 200, 225, 266, 274, &c., at various depths.

7. Sethocyrtis agamemnonis, n. sp. (Pl. 62, figs. 11, a, b).

Shell pear-shaped, rough, with sharp collar stricture. Length of the two joints = 2 : 10, breadth = 3 : 8. Cephalis subspherical, with very small pores and a small, pyramidal horn of half the length. Thorax inflate, ovate; in the uppermost part (beyond the collar stricture) with a ring of six to nine very large roundish pores, which are twice to four times as broad as the other irregular, roundish pores. (The shell is seen in fig. 11 from the apical pole, in fig. 11a with the cephalis, in fig. 11b without it, exhibiting the four central collar pores of the cortinar septum.) Mouth truncate, without prominent peristome.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.1 long, 0.08 broad.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

8. Sethocyrtis cassis, Haeckel.

Cornutella cassis, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 38. Cyrtocalpis cassis, Haeckel, 1862, Monogr. d. Radiol., p. 287.

Shell pear-shaped, smooth, with obliterated collar stricture. Length of the two joints = 4 : 13, breadth = 3 : 12. Cephalis ovate, with a conical horn of half the length. Thorax inflate, ovate, with subregular, circular, quincuncial pores, twice to three times as broad as the bars. Mouth constricted, truncate, two-thirds as broad as the thorax, without prominent peristome.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.13 long, 0.12 broad.

Habitat.—Fossil in Tertiary rocks of Sicily (Caltanisetta).

Genus 576. Sethocorys,^[81] Haeckel, 1881, Prodromus, p. 430.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with ovate or sub-cylindrical thorax, the mouth of which is constricted and prolonged into a ring-like peristome. Cephalis with an apical horn.

The genus Sethocorys differs from the preceding Sethocyrtis, its ancestral form, in the form of the constricted mouth, which is prolonged into a prominent, hyaline, tubular, or annular peristome.

1. Sethocorys achillis, n. sp. (Pl. 62, fig. 8).

Shell rough, pear-shaped, with distinct collar stricture. Length of the two joints = 4 : 8, breadth = 3 : 8. Cephalis ovate, with a stout pyramidal horn of half the length. Thorax nearly spherical, with regular, circular, quincuncial pores of the same breadth as the cephalic pores. Mouth constricted, half as broad as the thorax, with a broad, smooth, striated peristome.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.08 long, 0.08 broad.

Habitat.—Cosmopolitan; Mediterranean (Corfu), Atlantic, Indian, Pacific; many stations, at various depths.

2. Sethocorys patrocli, n. sp.

Shell thorny, pear-shaped, with slight collar stricture. Length of the two joints = 4 : 12, breadth = 3 : 10. Cephalis ovate, with a pyramidal horn of twice the length. Thorax ovate, truncate at both poles, with regular, circular pores, twice as broad as the cephalic pores. Mouth constricted, half as broad as the thorax, with a broad, smooth, prominent peristome.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.12 long, 0.1 broad.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 3000 fathoms.

3. Sethocorys armadillo, Haeckel.

Eucyrtidium armadillo, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf ix. fig. 10.

Shell slenderly ovate, smooth, with deep collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 6. Cephalis ovate, at the apex thorny, with a conical horn of the same length. Thorax smooth, ovate, truncate, with small, regular, circular pores, disposed in from twelve to fifteen transverse rows of the same breadth as the cephalic pores. Mouth constricted, half as broad as the thorax, with a broad, hyaline, prominent peristome.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.06 broad.

Habitat.—Fossil in Barbados.

4. Sethocorys odysseus, n. sp. (Pl. 62, fig. 10).

Shell ovate, smooth, with obliterated collar stricture. Length of the two joints = 2 : 9, breadth = 4 : 8. Cephalis hemispherical, with a slender, conical horn of the same length. Thorax nearly spherical, with regular, circular pores, of the same breadth as the cephalic pores, quincuncially disposed. Mouth constricted, only one-third as broad as the thorax, with a broad, hyaline, prominent peristome.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

5. Sethocorys amphora, Haeckel.

Lophophæna amphora, Stöhr, 1880, Palæontogr., vol. xxvi. p. 99, Taf. iii. fig. 11.

Shell ovate, mouth with distinct collar stricture. Length of the two joints = 1 : 5, breadth = 2 : 4. Cephalis hemispherical, with a short conical horn of half the length. Thorax ovate, truncate, with small, regular, circular, quincuncial pores. Mouth constricted, half as broad as the thorax, with a narrow, prominent, hyaline peristome.

Dimensions.—Cephalis 0.015 long, 0.03 broad; thorax 0.07 long, 0.06 broad.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte (Stöhr).

6. Sethocorys ajacis, n. sp.

Shell slenderly ovate, smooth, without external collar stricture, but with an internal septum. Length of the two joints = 1 : 3, breadth = 1 : 2. Cephalis conical, with a large pyramidal horn of twice the length, and sometimes with a smaller accessory horn at its base; its pores scarce, irregular. Thorax ovate, truncate, hyaline, in the greater part without pores, in the smaller part with from two to four transverse rows of small, circular pores only. Mouth constricted, with a large cylindrical, tubular, hyaline peristome, half as long as the shell.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.07 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 577. Lophophæna,^[82] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with ovate or subcylindrical thorax, the mouth of which is either truncate or constricted. Cephalis armed with several large horns.

The genus Lophophæna differs from the nearly allied Sethocorys and Dictyocephalus only in the armature of the large cephalis, which bears a group of large horns, often arranged in a corona of radial spines. Sometimes these spines are connected by anastomosing branches (like Arachnocorys).

Subgenus 1. Lophophænula, Haeckel.

Definition.—Horns of the cephalis simple, free, radial spines, neither branched nor connected.

1. Lophophæna galea, Ehrenberg.

Lophophæna galea orci, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin p. 245.

Lophophæna apiculata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 11.

? Cornutella spiniceps, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. ii. fig. 6.

Shell with slight collar stricture. Length of the two joints = 5 : 4, breadth = 5 : 6. Cephalis subglobular, with numerous bristle-shaped, radial spines, about as long as its radius. Thorax about the same size, truncate, conical, smooth, with wide open mouth. Pores in both joints of equal size, small, regular, circular.

Dimensions.—Cephalis 0.05 long, 0.05 broad; thorax 0.04 long, 0.06 broad.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms; also fossil in Barbados.

3. Lophophæna radians, Ehrenberg.

Lophophæna radians, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 9. ? Lophophæna lynx, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. fig. 13.

Shell with slight collar stricture. Length of the two joints = 4 : 6, breadth = 4 : 5. Cephalis subglobular, with numerous, stout, conical, radial spines, about as long as its diameter. Thorax of about the same size, subcylindrical, smooth, truncate, with wide open mouth. Pores in both joints of equal size, small, regular, circular.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.06 long, 0.05 broad.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific; also fossil in Barbados.

3. Lophophæna liothorax, n. sp.

Shell with distinct collar stricture. Length of the two joints = 4 : 10, breadth = 4 : 8. Cephalis subglobular, with large, circular, hexagonally-framed pores, and with numerous stout, conical, radial spines, about as long as its diameter. Thorax twice as long, ovate, smooth, truncate, with little constricted mouth, and with irregular, roundish pores, of very different sizes.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.1 long, 0.08 broad.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

4. Lophophæna echinocephala, n. sp.

Shell with deep collar stricture. Length of the two joints = 4 : 8, breadth = 4 : 9. Cephalis subglobular, of the same shape as in the preceding species. Thorax thorny, inflate, nearly spherical, with a constricted mouth of half the breadth, and with irregular, roundish, double-contoured pores.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.08 long, 0.09 broad.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

Subgenus 2. Lophophænoma, Haeckel.

Definition.—Horns of the cephalis connected by anastomosing branches.

5. Lophophæna circumtexta, Haeckel.

Lophophæna radians, var., Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. viii. figs. 7, 8.

Shell with slight collar stricture. Length of the two joints = 4 : 5, breadth = 4 : 5. Cephalis subglobular, with numerous conical, radial spines, about as long as its diameter, and at equal distances from the surface, connected by anastomosing branches. Thorax nearly cylindrical, smooth, little dilated towards the truncate, wide open mouth. Pores subregular, circular.

Dimensions.—Cephalis 0.04 long, 0.04 broad; thorax 0.05 long, 0.05 broad.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; also fossil in Barbados.

Genus 578. Dictyocephalus,^[83] Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 830.

Definition.—Sethocorida (vel Dicyrtida eradiata aperta) with ovate or subcylindrical thorax, the mouth of which is more or less constricted, either truncate or with a ring-like peristome. Cephalis rounded, without horn.

The genus Dictyocephalus has originated probably from Sethocorys by reduction and loss of the apical horn. The mouth is more or less constricted, either simple, truncate (Dictyocryphalus), or provided with a prominent, broad, hyaline, annular peristome (Dictyoprora).

Subgenus 1. Dictyoprora, Haeckel, 1881, Prodromus, p. 430.

Definition.—Mouth of the thorax constricted, with a prominent, ring-like or tubular, hyaline peristome.

1. Dictyocephalus amphora, n. sp. (Pl. 62, fig. 4).

Shell smooth, thick-walled, subovate, with slight collar stricture. Length of the two joints = 5 : 9, breadth = 6 : 8. Cephalis large, obtusely conical, with numerous oblique pore-canals. Thorax inflate, with six to eight transverse rows of roundish pores, increasing in size towards the base. Mouth constricted, one-third as broad as the thorax, with an internal diaphragm and a narrow hyaline peristome.

Dimensions.—Cephalis 0.05 long, 0.06 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Central Pacific, Stations 265 to 272, depth 2425 to 2925 fathoms.

2. Dictyocephalus urceolus, n. sp.

? Eucyrtidium Mongolfieri, Bury, 1862, Polycystins of Barbados, pl. v. fig. 2.

Shell smooth, thick-walled, urceolate, with obliterated collar stricture. Length of the two joints = 5 : 12, breadth = 4 : 10. Cephalis campanulate, with numerous oblique pore-canals. Thorax inflate, with five or six transverse rows of roundish pores of equal size. Mouth constricted, nearly half as broad as the thorax, with a broad hyaline peristome.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.12 long, 0.1 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

3. Dictyocephalus excellens, Haeckel.

Eucyrtidium excellens, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 2.

Shell annulate, thick-walled, urceolate, with slight collar stricture. Length of the two joints = 5 : 10, breadth = 4 : 7. Cephalis large, ovate-conical, with numerous oblique pore-canals. Thorax ovate, with ten to twelve transverse rows of regular, roundish pores, which are separated by prominent annular ribs. Mouth constricted, about half as broad as the thorax, with a broad hyaline peristome.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.1 long, 0.07 broad.

Habitat.—Fossil in Barbados.

4. Dictyocephalus ocellatus, Haeckel.

Dictyocephalus ocellatus, Haeckel, 1862, Monogr. d. Radiol., p. 297. ? Eucyrtidium ocellatum, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 299.

Shell smooth, thick-walled, with deep collar stricture. Length of the two joints = 3 : 9, breadth = 4 : 7. Cephalis subspherical, with numerous oblique pore-canals. Thorax inflate, campanulate, hyaline, only with three or four remote transverse rows of circular, double-contoured pores of equal size. Mouth constricted, one-third as broad as the thorax, with a narrow hyaline annular peristome.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.09 long, 0.07 broad.

Habitat.—North Atlantic, Greenland; Færöe Channel (Gulf Stream), John Murray.

5. Dictyocephalus crassiceps, Haeckel.

Eucyrtidium crassiceps, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 4.

Shell smooth, thick-walled, with sharp collar stricture. Length of the two joints = 4 : 6, breadth = 3 : 4. Cephalis ovate, in the upper part with scattered pores, in the lower part with one transverse row of pores. Thorax hyaline, subcylindrical, only with four or five remote transverse rows of small, circular pores. Mouth constricted, half as broad as the thorax, with a short hyaline peristome.

Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax 0.06 long, 0.04 broad.

Habitat.—Fossil in Barbados.

6. Dictyocephalus australis, n. sp. (Pl. 62, fig. 1).

Shell smooth, thick-walled, with slight collar stricture. Length of the two joints = 2 : 9, breadth = 3 : 6. Cephalis hemispherical, with few small pores. Thorax subcylindrical, with large, roundish, double-contoured pores, irregularly disposed. Mouth constricted, two-thirds as broad as the thorax, with a broad, hyaline peristome.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.09 long, 0.06 broad.

Habitat.—East coast of Australia, Station 164, surface.

7. Dictyocephalus mediterraneus, n. sp. (Pl. 62, fig. 2).

Shell rough, thin-walled, with slight collar stricture. Length of the two joints = 3 : 10, breadth = 4 : 8. Cephalis hemispherical, with small, circular pores. Thorax ovate, truncate, with much larger circular pores of different sizes and thin bars between them. Mouth little constricted, two-thirds as broad as the thorax, with a narrow, hyaline peristome.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.1 long, 0.08 broad.

Habitat.—Mediterranean, Smyrna (Haeckel), surface.

8. Dictyocephalus papillosus, Haeckel.

Eucyrtidium papillosum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 10.

Shell thin-walled, papillate, with obliterated collar stricture. Length of the two joints = 2 : 7, breadth = 3 : 5. Cephalis hemispherical, with small, circular pores. Thorax slenderly ovate, with larger, subregular, circular pores, separated by oblique series of conical papillæ. Mouth with a broad, hyaline peristome (the "third articulus" of Ehrenberg), separated by a stricture from the little broader thorax.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.07 long, 0.05 broad.

Habitat.—Western Tropical Pacific (Philippine Sea), depth 3300 fathoms.

9. Dictyocephalus tabulatus, n. sp.

Shell thin-walled, papillate, with obliterated collar stricture. Length of the two joints = 2 : 10, breadth = 3 : 7. Cephalis hemispherical, with small, circular pores. Thorax slenderly ovate, truncate, with large, subregular, circular, hexagonally-framed pores. Mouth little constricted, nearly as broad as the thorax, with a broad, hyaline peristome.

Dimensions.—Cephalis 0.02 long, 0.03 broad, thorax 0.1 long, 0.07 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

10. Dictyocephalus reticulum, Haeckel.

Dictyocephalus reticulum, Haeckel, 1862, Monogr. d. Radiol., p. 297. Eucyrtidium reticulum, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 300.

Shell thin-walled, smooth, with deep collar stricture. Length of the two joints = 2 : 8, breadth = 3 : 5. Cephalis subspherical, with small, circular pores. Thorax campanulate, with transverse rows of alternating square pores. Mouth little constricted, nearly as long as the thorax, with a narrow, prominent peristome.

Dimensions.—Cephalis 0.02 long, 0.03 broad; thorax 0.08 long, 0.05 broad.

Habitat.—Arctic Ocean, Greenland (Schaffner); Iceland (Krabbe).

11. Dictyocephalus ampulla, n. sp.

Shell thin-walled, smooth, with slight collar stricture. Length of the two joints = 1 : 4, breadth = 1 : 3. Cephalis subspherical, without pores, hyaline. Thorax inflate, subspherical, with scarce and small, widely-scattered, circular pores. Mouth constricted, only one-third as broad as the thorax, with a narrow, prominent peristome.

Dimensions.—Cephalis 0.02 long, 0.02 broad; thorax 0.08 long, 0.07 broad.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Subgenus 2. Dictyocryphalus, Haeckel, 1881, Prodromus, p. 430.

Definition.—Mouth of the thorax flat or truncate, without prominent ring-like peristome.

12. Dictyocephalus obtusus, Ehrenberg.

Dictyocephalus obtusus, Ehrenberg, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 830.

Lophophæna obtusa, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 40.

Cornutella obtusa, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 877.

Dictyocephalus obtusus, Haeckel, 1862, Monogr. d. Radiol., p. 296.

Shell smooth, thick-walled, with distinct collar stricture. Length of the two joints = 5 : 6, breadth = 4 : 5. Cephalis ovate, little smaller than the subcylindrical thorax. Pores subregular, circular, of little different sizes. Mouth truncate, without ring-like peristome.

Dimensions.—Cephalis 0.05 long, 0.04 broad; thorax 0.06 long, 0.05 broad.

Habitat.—Fossil in Tertiary rocks of Sicily (Caltanisetta), Grotte, &c.

13. Dictyocephalus globiceps, n. sp. (Pl. 62, fig. 7).

Shell rough, thin-walled, with distinct collar stricture. Length of the two joints = 6 : 8, breadth = 6 : 7. Cephalis subspherical, large, with circular, double-contoured pores. Thorax cylindrical, with irregular, roundish pores, the size of which, like the thickness of the wall, decreases gradually towards the truncate mouth, which has no ring-like peristome.

Dimensions.—Cephalis 0.06 long, 0.06 broad; thorax 0.08 long, 0.07 broad.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

14. Dictyocephalus cavea, n. sp.

Shell rough, thin-walled, with slight collar stricture. Length of the two joints = 3 : 10, breadth = 5 : 7. Cephalis hemispherical, thorny, with numerous regular, circular pores. Thorax subcylindrical, with very large, circular, hexagonally-framed pores (in nine longitudinal alternating rows), three to five times as broad as the cephalic pores. Mouth truncate, wide open, without ring-like peristome.

Dimensions.—Cephalis 0.06 long, 0.1 broad; thorax 0.2 long, 0.14 broad.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

15. Dictyocephalus capito, Ehrenberg.

Dictyocephalus capito, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 289, Taf. vii. fig. 24.

Shell smooth, thin-walled, with sharp collar stricture. Length of the two joints = 7 : 9, breadth = 6 : 8. Cephalis ovate, with numerous irregular, roundish, densely-crowded pores. Thorax ovate, with very few widely-scattered, irregular, roundish pores (broken off in Ehrenberg's figure). Mouth truncate, little constricted, without ring-like peristome.

Dimensions.—Cephalis 0.07 long, 0.06 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Western Tropical Pacific (Philippine Sea) Station 206, depth 2100 fathoms.

16. Dictyocephalus hispidus, Ehrenberg.

Dictyocephalus hispidus, Ehrenberg, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin; Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, p. 289, Taf. v. fig. 18.

Shell rough, thin-walled, with deep collar stricture. Length of the two joints = 3 : 4, breadth = 3 : 5. Cephalis subspherical, spiny, with the same irregular, roundish pores as the funnel-shaped or nearly ovate thorax. Mouth truncate, little narrower than the thorax, without ring-like peristome.

Dimensions.—Cephalis 0.03 long, 0.03 broad; thorax 0.04 long, 0.05 broad.

Habitat.—Tropical Atlantic, Mexican Gulf (Ehrenberg); Station 338, depth 1990 fathoms.

Subfamily 2. Sethocapsida, Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethocyrtida with the basal mouth of the shell fenestrated (vel Dicyrtida eradiata clausa).

Genus 579. Sethocapsa,^[84] Haeckel, 1881, Prodromus, p. 433 (sensu emendato).

Definition.—Sethocapsida (vel Dicyrtida eradiata clausa) with a free cephalis bearing an apical horn.

The genus Sethocapsa and the two following genera represent together the small subfamily of Sethocapsida, or those Dicyrtida in which the mouth of the thorax is closed, and no radial apophyses are present. Sethocapsa may be derived either from Lithopera by loss of the three radial rods, or from Sethocyrtis by closure of the mouth.

1. Sethocapsa pyriformis, n. sp. (Pl. 57, fig. 2).

Shell rough, pear-shaped, with slight collar stricture. Length of the two joints = 3 : 10, breadth = 3 : 8. Cephalis subspherical, with numerous small pores, and a short pyramidal or conical horn of half the length. Thorax ovate, with subregular, circular, quincuncial pores.

Dimensions.—Cephalis 0.03 diameter, thorax 0.1 long, 0.08 broad.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 3000 fathoms.

2. Sethocapsa lagena, Haeckel.

Lithopera lagena, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 4.

Shell smooth, pear-shaped, with sharp collar stricture. Length of the two joints = 3 : 8, breadth = 3 : 6. Cephalis pear-shaped, with few scarce pores, and a small conical horn of half the length. Thorax pear-shaped, with irregular, roundish pores. This species differs from the similar Lithopera lagena almost only in the complete absence of the three internal radial collar beams inside the thorax, and may be derived from it by their retrograde metamorphosis.

Dimensions.—Cephalis 0.03 diameter, thorax 0.08 long, 0.06 broad.

Habitat.—Fossil in Barbados.

3. Sethocapsa macroceros, n. sp.

Shell smooth, pear-shaped, with slight collar stricture. Length of the two joints = 2 : 11, breadth = 2 : 9. Cephalis subspherical, with small circular pores, and a very large, straight, pyramidal horn, of about the same length as the shell. Thorax ovate, with large, irregular, roundish pores, which are surrounded by polygonal frames.

Dimensions.—Cephalis 0.02 diameter, thorax 0.11 long, 0.09 broad.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

4. Sethocapsa nidus, Haeckel.

Lithopera nidus pendulus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 7.

Shell smooth, pear-shaped, with distinct collar stricture. Length of the two joints = 3 : 6, breadth = 3 : 5. Cephalis subspherical, with a large, straight, pyramidal horn of twice the length, and scarce small pores. Thorax ovate, also with very small and scarce pores.

Dimensions.—Cephalis 0.03 diameter, thorax 0.06 long, 0.05 broad.

Habitat.—Fossil in Barbados.

5. Sethocapsa bulla, n. sp.

Shell spiny, with slight collar stricture. Length of the two joints = 3 : 12, breadth = 4 : 12. Cephalis hemispherical, with small, scarce pores, and a conical horn of the same length. Thorax nearly spherical, with large, subregular, circular, quincuncial pores, twice as broad as the bars.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.12 long, 0.12 broad.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; fossil in Barbados.

6. Sethocapsa ampulla, n. sp.

Shell papillate, with slight collar stricture. Length of the two joints = 1 : 5, breadth = 1 : 5. Cephalis hemispherical, hyaline, without pores, with a large pyramidal horn of twice the length. Thorax nearly spherical, with large, irregular, roundish, lobulated pores.

Dimensions.—Cephalis 0.03 long, 0.04 broad; thorax 0.15 long, 0.15 broad.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

7. Sethocapsa staurocephala, Haeckel.

? Lithopera oxystauros, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 6. ? Lithopera amblystauros, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iii. fig. 5.

Shell smooth, with slight collar stricture. Length of the two joints = 3 : 4, breadth = 3 : 4. Cephalis large, ovate, with a conical horn of the same length, small scarce pores, and an internal frontal septum, composed of two crossed beams, a vertical and a horizontal. Thorax little larger than the cephalis, ovate, with irregular, small and scarce pores. (The two figures of Ehrenberg are either incomplete—in Lithopera amblystauros, the cephalic horn, and in Lithopera oxystauros, the basal part of the thorax, being broken off—or they belong to different Botryodea).

Dimensions.—Cephalis 0.03 diameter, thorax 0.04 diameter.

Habitat.—Fossil in Barbados.

Genus 580. Dicolocapsa,^[85] Haeckel, 1881, Prodromus, p. 433 (sensu emendato).

Definition.—Sethocapsida (vel Dicyrtida eradiata clausa) with a free cephalis, without apical horn.

The genus Dicolocapsa differs from the preceding Sethocapsa in the loss of the apical horn, and therefore bears to it the same relation that Dictyocephalus does to Sethocyrtis.

1. Dicolocapsa microcephala, n. sp. (Pl. 57, fig. 1).

Shell smooth, thin-walled, with distinct collar stricture. Cephalis small, subspherical, with small, crowded pores. Length of the two joints = 1 : 3, breadth = 1 : 3. Thorax also nearly spherical, three times as large as the cephalis, with small, irregularly scattered, circular pores, and much broader bars.

Dimensions.—Cephalis 0.03 diameter, thorax 0.09 diameter.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Dicolocapsa megacephala, n. sp.

Shell smooth, thin-walled, with sharp collar stricture. Cephalis large, conical, obtuse. Length of the two joints = 5 : 9, breadth = 6 : 8. Thorax ovate, truncate, with hemispherical base. Pores of both joints equal, subregular, circular, about as broad as the bars.

Dimensions.—Cephalis 0.05 long, 0.06 broad; thorax 0.09 long, 0.08 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Dicolocapsa platycephala, n. sp.

Shell papillate, thick-walled, with slight collar stricture. Cephalis flat, hemispherical, hyaline, without pores (or with few small pores). Length of the two joints = 2 : 11, breadth = 4 : 9. Thorax ovate, with small, regular, circular pores, half as broad as the bars.

Dimensions.—Cephalis 0.02 long, 0.04 broad; thorax 0.11 long, 0.09 broad.

Habitat.—Fossil in Barbados.

Genus 581. Cryptocapsa,^[86] Haeckel, 1881, Prodromus, p. 433.

Definition.—Sethocapsida (vel Dicyrtida eradiata clausa) with a cephalis hidden in the thorax, without apical horn.

The genus Cryptocapsa differs from the preceding Dicolocapsa, its ancestral form, in the peculiar shape of the cephalis, which is nearly perfectly enclosed in the upper part of the inflated thorax. It has, therefore, to the latter the same relation as Carpocanium bears to Anthocyrtis.

1. Cryptocapsa bacca, n. sp.

Cephalis spherical, with small circular pores enclosed in the upper part of the thorax, which is ovate, smooth, and exhibits regular, circular pores, about as broad as the bars.

Dimensions.—Cephalis 0.03 diameter, thorax 0.15 long, 0.12 broad.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Cryptocapsa pila, n. sp.

Cephalis spherical, with few small pores, enclosed in the upper part of the thorax, which is pear-shaped, spiny, and exhibits subregular, hexagonal pores, three times as broad as the bars. From each hexagon corner a small thorn arises.

Dimensions.—Cephalis 0.04 diameter, thorax 0.25 long, 0.17 broad.

Habitat.—Central Pacific, Station 269, depth 2900 fathoms.

Section III. TRICYRTIDA, Haeckel, 1881, Prodromus, p. 426, 434.

Definition.—Cyrtoidea trithalamia, with three-jointed shell, composed of cephalis, thorax, and abdomen, with two separating transverse constrictions, an upper collar, and a lower lumbar constriction.

Synopsis of the Families and Subfamilies of Tricyrtida.

Family LXV. Podocyrtida. Three radial apophyses.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth open,	Theopilida.
		Mouth closed,	Theoperida.
Family LXVI. Phormocyrtida. Numerous radial apophyses.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth open,	Theophormida.
		Mouth closed,	Theophænida.
Family LXVII. Theocyrtida. No radial apophyses.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth open,	Theocorida.
		Mouth closed,	Theocapsida.

Family LXV. Podocyrtida, n. fam. (Pl. 67, 68, 71-73).

Theopilida et Theoperida, Haeckel, 1881, Prodromus, p. 435, 436.

Definition.—Tricyrtida triradiata. (Cyrtoidea with a three-jointed shell, divided by two transverse constrictions into cephalis, thorax, and abdomen, and bearing three radial apophyses.)

The family Podocyrtida, composed of the Theopilida and Theoperida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is three-jointed and triradial, bearing three external apophyses. The two subfamilies differ in the shape of the basal mouth, which in the Theopilida is a simple wide opening, in the Theoperida closed by a lattice-plate. The latter are derived from the former by development of this closing plate. The phylogenetic origin of the Podocyrtida may be found in the Tripocyrtida, from which they are derived by development of an abdomen. But there are also some forms, which may be derived directly from the Plectoidea, and the origin of some other forms seems to be doubtful.

The Podocyrtida represent one of the largest groups of Cyrtoidea, very rich in numerous species, which are partly very common and widely distributed. A large number of living and fossil species has already been described and figured by Ehrenberg, (1872, 1879, loc. cit.). These mainly belong to his genera Podocyrtis, Pterocanium, Rhopalocanium, Lithornithium, &c., and many of them are very characteristic and common forms, in which the triradial structure of the three-jointed shell is visible at first view. We distinguish here twenty genera and one hundred and fifty species. The majority have a shell with a simple wide open mouth (Theopilida, fourteen genera and one hundred and eighteen species), in the minority the mouth is closed by lattice-work (Theoperida, six genera and thirty-two species).

The three joints of the shell have in the majority of Podocyrtida such a proportion that the cephalis is the smallest, the abdomen the largest, and the thorax between them intermediate in size. The cephalis bears almost constantly an apical horn; this is rarely reduced or lost; sometimes two or more horns are developed. The three radial apophyses arise originally from the base of the cephalis, and may from this point run along the shell-wall embedded in the lattice-plate of the thorax and the abdomen. They leave the latter at very different points, and form either lateral wings or terminal feet, sometimes both together. They are either solid or latticed, sometimes also branched, and of very various shape. Often only the three terminal feet surrounding the mouth have remained, whilst the ribs have disappeared.

Many species of this large family are very variable and connected with other different species by numerous transitional forms; the distinction of the genera described is also often very difficult.

Synopsis of the Genera of Podocyrtida.

I. Subfamily Theopilida. (Podocyrtida aperta.) Terminal mouth of the shell a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	A. Three free limbs or wings on the thorax (partly also on the abdomen).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	No free external appendages on the abdomen.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Three wings of the thorax solid.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Wings arising from the thorax,	582. Pterocorys.
								Three ribs enclosed in the wall of the thorax,	583. Theopilium.
								Wings arising free from the collar stricture,	584. Corocalyptra.
						Three wings of the thorax latticed.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Wings not prolonged into the cephalis,	585. Dictyoceras.
								Wings prolonged into the cephalis,	586. Pteropilium.
				Free appendages on the abdomen.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Three ribs prolonged into three terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Ribs and feet solid,	587. Theopodium.
								Ribs and feet latticed,	588. Pterocanium.
						Three free wings on the thorax. Numerous terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Wings and feet solid,	589. Pterocodon.
								Wings and feet latticed,	590. Dictyocodon.
		B. Free appendages not on the thorax, only on the abdomen.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Abdomen with three ribs and three feet,					591. Pleuropodium.
				Abdomen without lateral ribs, with three terminal feet.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Three feet solid, simple,	592. Podocyrtis.
								Three feet solid, ramified,	593. Thyrsocyrtis.
								Three feet latticed,	594. Dictyopodium.
II. Subfamily Theoperida. (Podocyrtida clausa.) Terminal mouth of the shell closed by a lattice-plate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Three lateral wings only on the thorax,					$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Wings solid,	595. Lithornithium.
								Wings latticed,	596. Sethornithium.
		Three lateral wings beginning from the thorax and prolonged into the abdomen,							597. Theopera.
		Three wings only on the abdomen.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Spell spindle-shaped, with three lateral wings on the abdomen.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	No horn on the basal pole,	598. Rhopalocanium.
								Basal pole of the shell with a horn,	599. Rhopalatractus.
				Shell three-sided pyramidal, with three terminal-feet on the basal corners,					600. Lithochytris.

Subfamily 1. Theopilida, Haeckel, Prodromus, p. 435.

Definition.—Podocyrtida with the terminal mouth of the shell open (vel Tricyrtida triradiata aperta).

Genus 582. Pterocorys,^[87] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three simple, free lateral wings arising from the sides of the thorax.

The genus Pterocorys, comprising numerous and some very common species, may be one of the oldest and most primitive Theopilida, and is perhaps the common ancestral form of all Tricyrtida. It exhibits three free lateral wings, arising from the sides of the thorax, like Lithomelissa among the Dicyrtida, and may be derived directly from this genus by development of an abdomen. The latter is commonly cylindrical or ovate, with a wide open mouth, whilst the thorax is either campanulate or three-sided and pyramidal.

Subgenus 1. Pterocyrtidium, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 531.

Definition.—Horn of the cephalis simple. Abdomen not prolonged into a narrow tube.

1. Pterocorys campanula, n. sp. (Pl. 71, fig. 3).

Shell campanulate, with two distinct strictures. Length of the three joints = 2 : 3 : 2, breadth = 2 : 4 : 6. Cephalis subovate, with a pyramidal horn of the same length. Thorax subconical, in the middle zone with three conical, horizontal wings, shorter than the cephalis, from which three thin ribs are decurrent to the mouth. Abdomen short and much dilated, with wide, truncate mouth. Pores nearly equal, small, subregular, circular.

Dimensions.—Length of the three joints, a 0.04, b 0.06, c 0.04; breadth, a 0.03, b 0.08, c 0.12.

Habitat.—Central Pacific, Stations 266 to 274, surface.

2. Pterocorys carinata, Haeckel.

Eucyrtidium carinatum, Haeckel, 1862, Monogr. d. Radiol., p. 322, Taf. vii. figs. 4-7.

Shell subovate, with two distinct strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis ovate, with a pyramidal horn of twice the length. Thorax campanulate, with three decurrent crests, from which in the lower part three small conical wings arise, shorter than the cephalis. Abdomen barrel-shaped, inflated, with wide, truncate mouth. Pores everywhere equal, small, regular, circular, quincuncial.

Dimensions.—Length of the three joints, a 0.25, b 0.05, c 0.075; breadth, a 0.25, b 0.09, c 0.1.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific; many stations, surface.

3. Pterocorys sabæ, Haeckel.

Pterocanium sabæ, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 299, Taf. x. fig. 17.

Shell campanulate or subconical, with two sharp strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, with a conical horn of the same length. Thorax subconical, in the lower third with three small, conical, little curved wings, shorter than the cephalis. Abdomen dilated towards the wide, truncate mouth. Pores subregular, circular, gradually increasing in size from the collar towards the mouth.

Dimensions.—Length of the three joints, a 0.025, b 0.06, c 0.08; breadth, a 0.02, b 0.08, c 0.09.

Habitat.—Indian Ocean, Zanzibar, 2200 fathoms (Pullen).

4. Pterocorys columba, n. sp. (Pl. 71, fig. 2).

Shell subovate, with two deep strictures. Length of the three joints = 2 : 5 : 4, breadth = 3 : 7 : 7. Cephalis hemispherical, with a curved conical horn of the same length. Thorax inflate, in the middle zone with three pyramidal downwardly divergent wings of nearly the same length. Abdomen short, inflate, little constricted towards the wide, truncate mouth. Pores all nearly equal, subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.04; breadth, a 0.03, b 0.07, c 0.07.

Habitat.—North Pacific, Station 237, surface.

5. Pterocorys falcifera, Haeckel.

Pterocanium falciferum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 107, Taf. iv. fig. 15. ? Pterocanium bibrachiatum, Stöhr, 1880, Palæontogr., vol xxvi. p. 106, Taf. iv. fig. 14.

Shell subovate, with two distinct strictures. Length of the three joints = 2 : 6 : 5, breadth = 3 : 9 : 10. Cephalis subspherical, with a conical horn of the same length. Thorax hemispherical, thick-walled, rough, with three stout triangular wings, which are about as long as the shell, and curved downwards, with upper convexity. Abdomen ovate, cylindrical, with wide, truncate mouth. Pores irregular, roundish, large and small intermingled; at the base of the abdomen (below the lumbar girdle) a circle of somewhat oblong, quadrangular pores.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.05; breadth, a 0.03, b 0.09, c 0.1.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte (Stöhr); Caltanisetta (Haeckel).

6. Pterocorys aquila, n. sp. (Pl. 71, fig. 5).

Shell ovate, with two deep strictures. Length of the three joints = 1 : 4 : 4, breadth = 1 : 8 : 6. Cephalis hemispherical, with a slender curved horn of three times the length. Thorax hemispherical, campanulate, spiny, prolonged above the lumbar girdle into three stout, three-sided prismatic wings, which are longer than the shell, fenestrated at the base, and S-shaped, curved. Abdomen barrel-shaped, with wide, truncate mouth. Pores irregular, roundish, of very different sizes.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.08; breadth, a 0.03, b 0.16, c 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

7. Pterocorys hirundo, n. sp. (Pl. 71, fig. 4).

Shell slender, ovate, with two deep strictures. Length of the three joints = 1 : 4 : 4, breadth = 2 : 5 : 5. Cephalis hemispherical, with a large pyramidal horn longer than the half shell. Thorax conical, spiny, prolonged above the lumbar girdle into three slender, triangular, prismatic wings, which are about as long as the shell, and slightly curved downwards, with lower convexity. Abdomen inflated, with wide, truncate mouth. Pores irregular, roundish, of very different sizes.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.08; breadth, a 0.04, b 0.1, c 0.1.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

8. Pterocorys barbadensis, Haeckel.

Pterocanium barbadense, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvii. fig. 6. Pterocyrtidium barbadense, Bütschli, 1882, Zeitschr. f. wiss. Zool., Bd. xxxvi., Taf. xxxiii. fig. 29, a, b.

Shell slender, smooth, with two slight strictures. Length of the three joints = 1 : 3 : 4, breadth = 2 : 4 : 4. Cephalis hemispherical, with a stout pyramidal horn of twice the length. Thorax campanulate-conical, in the lower half with three divergent, angular wings, which are slightly curved downwards, and as long as the thorax. Abdomen cylindrical, with wide, truncate mouth. Pores small, subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.07; breadth, a 0.04, b 0.07, c 0.07.

Habitat.—Fossil in Barbados.

9. Pterocorys apis, Haeckel.

Pterocodon apis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xix. fig. 3.

Shell slender, smooth, with two distinct strictures. Length of the three joints = 1 : 2 : 6, breadth = 2 : 3 : 4. Cephalis hemispherical, with a curved, conical horn of three times the length. Thorax very small, with three nearly horizontal, conical wings, which are slightly curved downwards, and twice as long as the thorax. Abdomen cylindrical, three times as long as the thorax, with wide, truncate mouth. Pores small, subregular, circular. Differs from all other species in the very small size of the thorax; the abdomen is broken off in Ehrenberg's figure.

Dimensions.—Length of the three joints, a 0.15, b 0.02, c 0.06; breadth, a 0.02, b 0.03, c 0.04.

Habitat.—Cosmopolitan; Atlantic, Pacific, many stations; also fossil in Barbados.

10. Pterocorys melitta, Haeckel.

Rhopalocanium ornatum, Bury, 1862, Polycystins of Barbados, Taf. vi. fig. 4.

Shell slender, smooth, with two deep strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 2. Cephalis subspherical, with a pyramidal horn of twice the length. Thorax broad and short, loaf-shaped, with three conical wings, which are horizontally expanded, and half as long as the shell. Abdomen cylindrical, with wide, truncate mouth. Pores small, subregular, circular.

Dimensions.—Length of the three joints, a 0.025, b 0.03, c 0.09; breadth, a 0.03, b 0.06, c 0.06.

Habitat.—Fossil in Barbados.

11. Pterocorys turgida, Haeckel.

Lychnocanium turgidum, Ehrenberg, 1885, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. vii. fig. 6.

Shell thick-walled, pear-shaped, smooth, with sharp collar stricture. The lumbar stricture is not distinct externally, but is represented by a broad, internal, annular septum. Length of the three joints = 1 : 6 : 3, breadth = 2 : 7 : 6. Cephalis hemispherical, with a stout pyramidal horn of the same length. Thorax and abdomen together pear-shaped, inflated. Immediately above the lumbar stricture three stout, conical, lateral wings, as long as the cephalis, arise. Mouth very small, about as broad as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.12, c 0.06; breadth, a 0.03, b 0.13, c 0.12.

Habitat.—Fossil in Barbados.

Subgenus 2. Pterosyringium, Haeckel.

Definition.—Horn of the cephalis simple. Abdomen prolonged into a narrow cylindrical tube.

12. Pterocorys tubulosa, n. sp. (Pl. 68, fig. 6).

Pterosyringium tubulosum, Haeckel, 1879, Atlas, loc. cit.

Shell thick-walled, rough, with two slight strictures. Length of the three joints = 1 : 4 : 4, breadth = 1 : 3 : 1. Cephalis hemispherical, with a conical horn of the same length. Thorax ovate, in the upper half with three ribs, arising into short, triangular, slightly prominent wings. Abdomen prolonged into a cylindrical, narrow tube of the same length as the thorax. Terminal mouth very narrow. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.03, b 0.12, c 0.12; breadth, a 0.03, b 0.09, c 0.03.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

13. Pterocorys pipetta, n. sp.

Shell thin-walled, smooth, with two slight strictures. Length of the three joints = 1 : 6 : 3, breadth = 1 : 3 : 1. Cephalis ovate, with a conical horn of twice the length. Thorax ovate, in the middle zone with three conical wings of the same length, curved slightly downwards (like those of Pterocorys columba, Pl. 71, fig. 2). Abdomen constricted into a cylindrical tube half as long as the thorax, with narrow mouth. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.12, c 0.06; breadth, a 0.02, b 0.06, c 0.02.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

Subgenus 3. Pterocorythium, Haeckel.

Definition.—Horn of the cephalis double or multiple. Abdomen not prolonged into a narrow tube.

14. Pterocorys rhinoceros, n. sp. (Pl. 71, fig. 1).

Shell very delicate and thin-walled, with two sharp strictures. Length of the three joints = 2 : 10 : 3, breadth, 3 : 11 : 9. Cephalis obtuse, conical, with two divergent, conical horns of equal length. Thorax triangular, pyramidal; from its three edges there arise on the middle joint three conical descending wings (little larger than the horns), and from the base of each wing descend two divergent crests, forming at the sides of the pyramid three rounded lobes. Abdomen short, cylindrical, with wide, truncate mouth. Network of the whole shell very delicate, with very small and numerous, regular, circular, hexagonally-framed pores.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.03; breadth, a 0.03, b 0.11, c 0.09.

Habitat.—Central Pacific, Stations 270 to 274, surface, and in various depths.

15. Pterocorys prismatica, n. sp.

Shell very delicate and thin-walled throughout, with fine fenestration similar to that of the preceding species, but differing from it in the form of the abdomen, which is much larger, three-sided and prismatic; three edges of the prism decurrent from the bases of the three short wings. Length of the three joints = 1 : 4 : 5, breadth = 2 : 6 : 6. No lobes at the thorax. Mouth wide open, truncate, triangular.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.1; breadth, a 0.04, b 0.12, c 0.12.

Habitat.—South Pacific, Station 288, surface.

16. Pterocorys tricornis, n. sp.

Shell spiny, with two deep strictures. Length of the three joints = 1 : 5 : 3, breadth = 1 : 7 : 5. Cephalis subspherical, with three stout, pyramidal, divergent horns, which are three times as long, and bear three serrated edges. Thorax three-sided pyramidal, spiny; its three edges prolonged at the girdle into three stout, triangular, prismatic wings of the same length, little curved. Abdomen short, cylindrical, with wide open, truncate mouth. Pores irregular, polygonal, roundish.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.06; breadth, a 0.03, b 0.14, c 0.1.

Habitat.—North Pacific, Station 244, surface.

17. Pterocorys zittelii, Haeckel.

Pterocyrtidium zittelii, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. pp. 531, 540, Taf. xxxiii. figs. 28, a, b.

Shell thin-walled, rough, with two slight strictures. Length of the three joints = 2 : 5 : 7, breadth = 3 : 5 : 5. Cephalis hemispherical, armed with a very large, prismatic, vertical horn, which is half as long as the shell, and at its base surrounded by several (three to five) shorter, upwardly diverging horns. Thorax campanulate, in the upper half with three short, downwardly diverging, conical wings. Abdomen subcylindrical, with wide, truncate mouth. Pores small, subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.07; breadth, a 0.03, b 0.05, c 0.05.

Habitat.—Fossil in Barbados.

18. Pterocorys macroptera, n. sp.

Shell thin-walled, smooth, with two slight strictures. Length of the three joints = 1 : 3 : 2, breadth = 1 : 4 : 3. Cephalis hemispherical, armed with two larger and six to eight smaller, conical, divergent horns of different lengths. Thorax three-sided pyramidal; its three edges prolonged into three very large diverging wings, which are slender, three-sided, prismatic, and nearly twice as long as the shell. Abdomen short, cylindrical, with wide, truncate mouth. Pores irregular, roundish, in the middle part of the shell (on both sides of the girdle) much larger than in the upper and lower part.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.06; breadth, a 0.04, b 0.12. c 0.1.

Habitat.—South Atlantic, Station 335, surface.

Genus 583. Theopilium,^[88] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three lateral ribs enclosed in the wall of the thorax, without free lateral or terminal appendages.

The genus Theopilium differs from all the other Theopilida in the absence of free external appendages; it has neither lateral wings nor terminal feet, but three divergent ribs are enclosed in the wall of the thorax. It agrees in this character with the Dicyrtid Lamprodiscus, and may be derived directly from this by development of an abdomen.

1. Theopilium tricostatum, n. sp. (Pl. 70, fig. 6).

Shell flatly conical, smooth. Length of the three joints = 1 : 4 : 2, breadth = 2 : 6 : 10. Cephalis subspherical, with a thin oblique horn of the same length. Thorax with three stout ribs in its wall, and with subregular, hexagonal pores increasing in size towards the girdle. Abdomen flatter than the thorax, without ribs, nearly horizontal, with subregular, square pores, disposed in four to six concentric, subcircular series of different sizes; decreasing in size towards the wide open mouth. Seen from the side, this species resembles Corocalyptra agnesæ, (Pl. 59, fig. 3).

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.03, b 0.12, c 0.2.

Habitat.—Central Pacific, Stations 260 to 274, surface.

2. Theopilium triradiatum, n. sp.

Shell flatly conical, smooth, in general of the same form as, and with similar fenestration to, the preceding species, but different in the proportions. Length of the three joints = 1 : 4 : 2, breadth = 2 : 4 : 6. Cephalis hemispherical, with two divergent, thin horns of the same length. Thorax more elevated, about as high as broad. The three divergent ribs are not limited to the thorax, but prolonged through the whole abdomen, the outline of which is a prolongation of that of the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.1, c 0.05; breadth, a 0.05, b 0.1, c 0.15.

Habitat.—Tropical Atlantic, Station 347, surface.

3. Theopilium cranoides, Haeckel.

Eucyrtidium cranoides, Haeckel, 1862, Monogr. d. Radiol., p. 320, Taf. vii. figs. 1-3.

Shell campanulate-conical, smooth. Length of the three joints = 2 : 5 : 4, breadth = 3 : 9 : 10. Cephalis ovate, with a straight, excentric, prismatic horn of the same length. The campanulate thorax is separated from it by no external collar stricture, but by an internal septum. From the base of the horn arise three divergent radial ribs, running in the wall of the two first joints to the lumbar stricture (loc. cit., Taf. vii. fig. 3). Abdomen short and wide, without ribs. Pores rather large, regular, circular, quincuncial, in the cephalis smaller. Central capsule four-lobed.

Dimensions.—Length of the three joints, a 0.027, b 0.054, c 0.047; breadth, a 0.03, b 0.09, c 0.1.

Habitat.—Mediterranean (Messina), surface.

Genus 584. Corocalyptra,^[89] n. gen.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three simple, free, lateral wings, arising from the collar stricture between cephalis and thorax.

The genus Corocalyptra comprises a small number of very elegant hat-shaped Tricyrtida, which resemble greatly Eucecryphalus among the Dicyrtida. As in the latter, three free, radial spines, or simple wings, corresponding to the three basal feet of Cortina, arise from the collar stricture between the small hemispherical cephalis and the large, flatly conical thorax. Corocalyptra differs from Eucecryphalus, its ancestral form, in the development of a flat and broad abdomen, which is a prolongation of the thorax, and may be compared to the brim of a hat.

1. Corocalyptra agnesæ, n. sp. (Pl. 59, fig. 3).

Shell flatly conical or hat-shaped. Length of the three joints = 1 : 4 : 2, breadth = 2 : 8 : 12. Cephalis hemispherical, with an oblique, small, conical horn of the same length. From the slight collar stricture arise three slender, conical feet of equal length, twice as long as the apical horn, nearly horizontally divergent. Lateral outline of the conical thorax straight, of the flatter abdomen convex; the smooth margin of the abdomen turned inwards. Network delicate, with subregular, hexagonal pores.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.03, b 0.15, c 0.24.

Habitat.—Central Pacific, Station 270, surface.

2. Corocalyptra elisabethæ, n. sp. (Pl. 59, fig. 10).

Shell flatly conical, hat-shaped, very similar to the preceding species, but with different proportions. Length of the three joints = 1 : 4 : 2; breadth = 1 : 7 : 10. Cephalis very small, with an oblique horn of the same length. The three feet are of different sizes, the caudal odd foot being twice as long as the two lateral, which are equal to the horn. Lateral outline of the campanulate thorax convex, of the flatter abdomen less convex. Margin of the mouth flat.

Dimensions.—Length of the three joints, a 0.015, b 0.06, c 0.03; breadth a 0.02, b 0.14, c 0.2.

Habitat.—Tropical Atlantic, Station 347, surface.

3. Corocalyptra emmæ, n. sp. (Pl. 59, fig. 4).

Shell nearly conical, hat-shaped. Length of the three joints = 1 : 3 : 1, breadth = 1 : 5 : 7. Cephalis hemispherical, with a straight horn of the same length. Feet of the collar larger than in the preceding species, the two lateral smaller being directed upwards, the larger odd caudal downwards. Thorax slightly campanulate; its hexagonal meshes two to four times as large as those of the short, convex abdomen, which is turned inwards.

Dimensions.—Length of the three joints, a 0.02, b 0.09, c 0.03; breadth, a 0.025, b 0.13, c 0.17.

Habitat.—Central Pacific, Station 273, surface.

4. Corocalyptra margarethæ, n. sp.

Shell nearly conical, hat-shaped, very similar to the preceding species, but with much more delicate hexagonal network, with thread-like bars. Length of the three joints = 1 : 7 : 2, breadth = 1 : 10 : 12. Cephalis hemispherical, with six bristle-shaped spines of half the length of the shell; three horns divergent upwards, and three alternating feet divergent downwards. Thorax nearly conical. Abdomen flatter.

Dimensions.—Length of the three joints, a 0.015, b 0.1, c 0.03; breadth, a 0.02, b 0.15, c 0.18.

Habitat.—North Pacific, Station 236, surface.

5. Corocalyptra ludovicæ, n. sp.

Shell flatly campanulate or hat-shaped. Length of the three joints = 1 : 4 : 3, breadth = 2 : 7 : 10. Cephalis hemispherical, with six bristle-shaped spines, about one-fourth to one-third as long as the shell; three horns diverging upwards, and three alternate feet diverging downwards. Thorax nearly conical. Abdomen much larger than in all preceding species, inflated, with convex, lateral outline; its mouth-edge curved inwards. The network is much finer than in the similar Corocalyptra emmæ (Pl. 59, fig. 4), and the abdomen is relatively twice as long and broad.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.06; breadth, a 0.04, b 0.14, c 0.2.

Habitat.—Central Pacific, Station 271, surface.

Genus 585. Dictyoceras,^[90] Haeckel, 1862, Monogr. d. Radiol., p. 333.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three latticed free lateral wings on the sides of the thorax, which are not prolonged into the cephalis.

The genus Dictyoceras and the following Pteropilium agree with the two preceding genera in the possession of three lateral wings on the sides of the thorax; but whilst these in the latter are simple solid spines, they are in the former vertical fenestrated plates. Dictyoceras may be derived from Pterocorys by development of a vertical lattice-plate between the thorax and the three free lateral spines arising from it.

1. Dictyoceras insectum, n. sp. (Pl. 71, figs. 6, 7).

Shell with two distinct strictures. Length of the three joints = 1 : 3 : 2, breadth = 2 : 4 : 3. Cephalis hemispherical, with a slender pyramidal horn of twice the length. Thorax subspherical, in the upper half with three divergent lattice-wings of the same length, each of which represents a slender, fenestrated, three-sided pyramid. Abdomen subovate, with wide, truncate mouth (in the figured specimen broken off). Pores circular, small, of different sizes.

Dimensions.—Length of the three joints, a 0.025, b 0.055, c 0.04; breadth, a 0.035, b 0.08, c 0.06.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

2. Dictyoceras formica, n. sp. (Pl. 71, fig. 8).

Shell with obliterate collar, but deep lumbar stricture. Length of the three joints = 1 : 2 : 3, breadth = 2 : 5 : 4. Cephalis conical, with an oblique curved horn of the same length. Thorax with three vaulted swellings between the three prominent, diverging lattice-wings, the apex of which is prolonged downwards into a solid curved spine, half as long as the inflated abdomen. Mouth little constricted. Pores irregular, roundish, of different sizes.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.06; breadth, a 0.03, b 0.1, c 0.09.

Habitat.—North Atlantic, Station 353, surface.

3. Dictyoceras melitta, n. sp. (Pl. 71, fig. 9).

Shell with two deep strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 6 : 5. Cephalis subspherical, with two conical divergent horns of the same length. Thorax three-sided pyramidal, the three edges prolonged into three lattice-wings of the same form, with short, terminal spines. Abdomen inflated, subovate, with constricted mouth. Pores small, regular, circular, of equal size, with very thin bars.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.12; breadth, a 0.04, b 0.18, c 0.15.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

4. Dictyoceras bombus, n. sp. (Pl. 71, fig. 10).

Shell with deep collar, but evanescent lumbar stricture. Length of the three joints = 1 : 5 : 3, breadth = 1 : 6 : 7. Cephalis subspherical, with a conical horn of the same length. Thorax campanulate, with three short and broad, triangular lattice-wings, the upper edge of which is nearly horizontal, the lower nearly vertical and decurrent from the height of the collar to the lumbar stricture. Abdomen inflated, with constricted mouth of half the breadth. Pores small, subregular, circular, of nearly equal size.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.06; breadth, a 0.025, b 0.12, c 0.14.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

5. Dictyoceras virchowii, Haeckel.

Dictyoceras virchowii, Haeckel, 1862, Monogr. d. Radiol., p. 333, Taf. viii. figs. 1-5. Lithornithium dictyoceras, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 1860, p. 840.

Shell with two distinct strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 5 : 6. Cephalis subspherical, with an oblique curved horn of the same length. Thorax conical, with three broad, triangular lattice-wings different in size and direction, two of which are directed outwards, the third downwards—each terminated by a strong spine. Abdomen oblique, inflated, with wide open, truncate mouth. On the shell surface some few conical spines are scattered. Pores irregular, roundish, of different sizes. On the peculiar symmetry of this remarkable form, compare the detailed description in my Monograph.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.08; breadth, a 0.02, b 0.1, c 0.12.

Habitat.—Mediterranean, Messina, surface.

Genus 586. Pteropilium,^[91] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three latticed free lateral wings on the sides of the thorax, prolonged into the horn of the cephalis in the form of three vertical, free cephalic wings.

The genus Pteropilium differs from the preceding closely allied Dictyoceras in the development of three free, vertical, latticed cephalic wings, expanded between the apical horn of the cephalis and the three wings of the thorax; they may be direct prolongations of the latter. Pteropilium, however, may also be derived directly from the Dicyrtida Callimitra or Clathrocorys by development of an abdomen. All these interesting forms are closely allied to the Plectoidea.

Subgenus 1. Clathropilium, Haeckel, 1881, Prodromus, p. 435.

Definition.—Thorax completely latticed, without three larger lateral holes between the three wings.

1. Pteropilium stratiotes, n. sp. (Pl. 70, figs. 9, 10).

Shell thin-walled, with two deep strictures. Length of the three joints = 1 : 5 : 4, breadth = 2 : 6 : 9. Cephalis hemispherical, with a vertical, straight, prismatic horn of three times the length. Thorax inflated, oblique, with three slender, nearly straight, widely divergent ribs, beginning from the collar stricture and united in its centre with the centripetal prolongation of the horn. The basal half of the three ribs is enclosed in the thorax wall, whilst the distal half lies outside it, and is connected with its lower half only by two divergent, reticulated wings. The upper edge of the ribs is connected with the occipital horn by a vertical, loosely reticulated, triangular wing. Abdomen half as long as the thorax, also of irregular and oblique form, with knee-shaped outline and a wide, truncate mouth. Network with irregular polygonal, for the most part quadrangular, meshes, separated by thin bars and forming irregular transverse rows. Some stronger, vein-like ribs ramify in the wall, diverging towards the mouth.

Dimensions.—Length of the three joints, a 0.03, b 0.1, c 0.08; breadth, a 0.04, b 0.12, c 0.18.

Habitat.—Central Pacific, Station 271, surface.

2. Pteropilium hoplites, n. sp.

Shell in the general form and in the irregular, quadrangular fenestration similar to the preceding species, but more heavy and with different proportions. Length of the three joints = 1 : 6 : 4, breadth = 2 : 6 : 8. Cephalis twice as broad as in Pteropilium stratiotes. Thorax more slender and subovate. Abdomen truncate, conical, gradually dilated, with straight, non-geniculate outline. Network coarser, with larger square meshes and thicker bars.

Dimensions.—Length of the three joints, a 0.03, b 0.12, c 0.08; breadth, a 0.05, b 0.12, c 0.16.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Pteropilium eques, n. sp.

Shell in the general form and in the irregular, quadrangular fenestration similar to those of the two preceding species, but more slender and with different proportions. Length of the three joints = 1 : 3 : 2, breadth = 2 : 4 : 4. Cephalis flatter. Thorax subconical, also flatter. Abdomen short, cylindrical, with straight outline. Network looser than in the two preceding species, with larger square meshes and thinner bars.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.06; breadth a 0.06, b 0.12, c 0.12.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Subgenus 2. Arachnopilium, Haeckel, 1881, Prodromus, p. 435.

Definition.—Thorax with three large lateral holes between the three latticed wings.

4. Pteropilium clathrocanium, n. sp. (Pl. 64, fig. 7).

Arachnopilium clathrocanium, Haeckel, Prodromus, 1881, p. 435.

Shell very delicate, with two deep strictures. Length of the three joints = 2 : 4 : 2, breadth = 2 : 10 : 5. Cephalis subspherical, with circular, polygonally-framed pores, and a central, three-sided pyramidal, apical horn of twice the length. Thorax three-sided pyramidal, with three large, ovate holes between three prominent latticed wings. From its surface arises a very delicate, arachnoidal network with irregular, polygonal meshes, enveloping also the entire cephalis. Abdomen wide and short, as long as the cephalis, and half as broad as the distance of the wings, twice as broad as the constricted mouth.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.04; breadth, a 0.05, b 0.2, c 0.1.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 587. Theopodium,^[92] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three divergent solid ribs, which lie in the wall of the thorax and the abdomen, and are prolonged into three solid terminal feet.

The genus Theopodium and the following closely allied Pterocanium differ from the preceding four genera in the development of the three radial rods or the primary cortinar spines, which are not free lateral wings, but longitudinal ribs enclosed in the wall of the thorax and abdomen, and prolonged over the basal mouth into three free terminal feet. These are solid in Theopodium, which, therefore, corresponds to Lychnocanium among the Dicyrtida.

1. Theopodium tricostatum, n. sp. (Pl. 97, fig. 14).

Shell three-sided pyramidal, thorny, with two distinct strictures. Length of the three joints = 1 : 2 : 2, breadth = 1 : 3 : 4. Cephalis hemispherical, with a stout conical horn of the same length. Thorax with regular, circular, hexagonally-framed pores. Abdomen with irregular, roundish pores of very different sizes. From the middle part of the thorax arise the three prominent, wing-like edges of the pyramid, which are prolonged over its wide mouth into three stout, pyramidal, divergent feet about as long as the thorax, with dentate, lamellar edges.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.06; breadth, a 0.04, b 0.09, c 0.12.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

2. Theopodium pyramidale, n. sp.

Shell three-sided pyramidal, rough, without external strictures, but with two broad internal girdles. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 8. Cephalis with a thick horn of the same length, conical. Thorax with very small, regular, circular pores. Abdomen with irregular, roundish pores of very different sizes. From the collar stricture arise the three rectilinear edges of the pyramid, which are prolonged over its wide-open mouth into three stout, divergent, pyramidal feet, about as long as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.04, b 0.075, c 0.15.

Habitat.—Fossil in Barbados.

Genus 588. Pterocanium,^[93] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three divergent ribs, which run along the thorax and abdomen, and are prolonged into three latticed terminal feet.

The genus Pterocanium differs from the preceding Theopodium in the fenestration of the three terminal feet, which are basal prolongations of the three radial ribs, enclosed in the wall of the thorax and the abdomen. Often also these ribs are partly or wholly fenestrated. It corresponds to Lychnodictyum among the Dicyrtida, and may be derived from this by development of an abdomen. The latter forms sometimes three concave bays, at other times three convex lobes between the three latticed feet.

Subgenus 1. Pterocanarium, Haeckel.

Definition.—Free basal edge of the abdomen between the three feet concave, forming three shallower or deeper bays between them.

1. Pterocanium proserpinæ, Ehrenberg.

Pterocanium proserpinæ, Ehrenberg, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, p. 299, Taf. xi. fig. 22. Pterocanium proserpinæ, Haeckel, 1862, Monogr. d. Radiol., p. 332.

Shell campanulate, rough. Length of the three joints = 1 : 4 : 2, breadth 1 : 5 : 6. Cephalis subspherical, with a triangular-pyramidal vertical horn of thrice the length. Thorax hemispherical, without prominent swellings. Abdomen shorter, with three concave basal bays. Pores in the thorax and abdomen nearly equal, subregular, circular. Feet from the girdle (or the lumbar stricture) little divergent, nearly straight.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.3, b 0.1, c 0.12.

Habitat.—Mediterranean, Candia, Spratt, depth 1100 fathoms.

2. Pterocanium gravidum, n. sp., (Pl. 73, fig. 3).

Shell campanulate, nearly three-sided pyramidal, smooth. Length of the three joints = 1 : 4 : 3, breadth = 1 : 6 : 10. Cephalis subspherical, with a pyramidal straight horn of twice the length. Thorax hemispherical, without prominent swellings. Abdomen shorter, with three concave basal bays; its network prolonged to the ends of the feet. Pores in the thorax and abdomen of nearly equal size, irregular, roundish. Feet from the girdle strongly divergent, with convex back.

Dimensions.—Length of the three joints, a 0.015, b 0.075, c 0.06; breadth, a 0.02, b 0.12, c 0.2.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

3. Pterocanium orcinum, n. sp. (Pl. 73, fig. 2).

Shell campanulate, nearly three-sided pyramidal, covered with conical spines. Length of the three joints = 1 : 4 : 3, breadth = 1 : 5 : 6. Cephalis hemispherical, with a conical horn of the same length. Thorax without prominent swellings, with subregular, circular pores. Abdomen shorter, with three concave basal edges and irregular, polygonal pores. Feet from the girdle strongly divergent, nearly straight.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.06; breadth, a 0.03, b 0.1, c 0.12.

Habitat.—Central Pacific, Station 263 to 274, depth 2350 to 2925 fathoms.

4. Pterocanium contiguum, Ehrenberg.

Pterocanium contiguum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xvii. fig. 7.

Shell three-sided pyramidal, smooth. Length of the three joints = 1 : 3 : 2, breadth = 1 : 4 : 6. Cephalis small, subspherical, with a large conical horn three times the length. Thorax and abdomen with small, regular, circular pores of equal size, densely crowded together, with thin bars. Abdomen shorter, with three concave basal edges. Feet very thick, straight, from the girdle strongly divergent.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.025; breadth a 0.02, b 0.08, c 0.12.

Habitat.—Fossil in Barbados.

5. Pterocanium pyramis, n. sp. (Pl. 68, fig. 7).

Shell three-sided pyramidal, smooth. Length of the three joints = 1 : 4 : 3, breadth = 2 : 4 : 6. Cephalis hemispherical, with a conical horn of the same length. Thorax campanulate, with fifteen to twenty prominent longitudinal ribs, separating as many rows of regular, circular pores. Abdomen shorter, with three concave basal bays, and irregular, roundish pores. Feet very strong, pyramidal, straight, gradually divergent from the girdle.

Dimensions.—Length of the three joints, a 0.025, b 0.08, c 0.06; breadth, a 0.04, b 0.08, c 0.12.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

6. Pterocanium virgineum, n. sp. (Pl. 73, fig. 6).

Shell nearly three-sided pyramidal, smooth. Length of the three joints = 1 : 4 : 8, breadth 2 : 6 : 9. Cephalis hemispherical, with a conical straight horn three times the length. Thorax campanulate, with three slight swellings between the three knee-shaped ribs, and with regular circular pores. Abdomen longer, with three concave basal bays, and with very small and numerous pores (much smaller than those of the thorax). At both sides of the three prominent abdominal crests, two rows of larger, nearly square pores occur. Feet slender, nearly straight, divergent.

Dimensions.—Length of the three joints, a 0.15, b 0.06, c 0.12; breadth, a 0.03, b 0.09, c 0.14.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

7. Pterocanium prætextum, Haeckel.

Lychnocanium prætextum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. x. fig. 2.

Shell nearly three-sided prismatic, smooth. Length of the three joints = 1 : 2 : 1, breadth = 1 : 4 : 4. Cephalis subspherical, with a straight, conical horn of three times the length. Thorax campanulate with three slight swellings between the three knee-shaped ribs, and with regular, circular pores. Abdomen smaller, with three deep concave basal bays, and with irregular, roundish pores. Feet longer than the shell, slender, pyramidal, straight, parallel.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.02; breadth, a 0.02, b 0.07, c 0.07.

Habitat.—Indian Ocean, Ceylon (Haeckel); Zanzibar (Pullen).

8. Pterocanium depressum, Haeckel.

Lychnocanium depressum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. x. fig. 1.

Shell (including the feet) nearly three-sided prismatic, rough. Length of the three joints = 1 : 2 : 1, breadth = 1 : 6 : 6. Cephalis subspherical, with a conical horn of the same length. Thorax a very flat and broad triangular pyramid, three times as broad as long. Abdomen smaller, with three deep, parabolic, concave bays. Pores irregular, roundish. Feet longer than the shell, slender, pyramidal, straight, parallel.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.02; breadth, a 0.025, b 0.12, c 0.12.

Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).

9. Pterocanium campanella, Haeckel.

Lychnocanium campanella, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. viii. fig. 12 Podocyrtis campanella, Ehrenberg, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 769.

Shell campanulate, smooth, with three high fenestrated crests and deep collar stricture. Length of the three joints = 1 : 3;1, breadth = 1 : 4 : 3. Cephalis subspherical, with a slender horn of the same length. Thorax inflated, campanulate, with three vaulted swellings between the three curved ribs. Abdomen short, with three semicircular bays between the three feet. Pores of the whole shell regular, circular, small, and numerous. Feet broad, triangular, shorter than the thorax, with convex back and convergent ends.

Dimensions.—Length of the three joints, a 0.015, b 0.06, c 0.2; breadth a 0.02, b 0.08, c 0.07.

Habitat.—Western Tropical Pacific, Philippine Sea, 3300 fathoms (Brooke).

10. Pterocanium tricolpum, n. sp. (Pl. 73, fig. 1).

Shell nearly three-sided prismatic, smooth, with three high fenestrated crests and two deep strictures. Length of the three joints = 1 : 3 : 2, breadth = 1 : 5 : 5. Cephalis subspherical, with an oblique, conical horn of the same length. Thorax inflated, with three highly vaulted bosoms between the three high crests, and with subregular, circular pores. Abdomen shorter, with three concave (or nearly rectangular, square) basal bays between the three feet, and with irregular, roundish pores, three to four pairs of larger pores occurring at the sides of the base of the feet. Feet nearly as long as the shell, with fenestrated bases, nearly straight and parallel; somewhat convergent, with convex back. (Often the concave bays between the three feet are not square, as in the specimen figured, but semicircular.) The ends of the feet are sometimes strongly convergent. The vaultings of the three swellings and the reticulation are also variable; the whole form is often irregular.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.025, b 0.1, c 0.1.

Habitat.—Cosmopolitan; Atlantic, Pacific; many stations, surface.

Subgenus 2. Pterocanidium, Haeckel.

Definition.—Free basal edge of the abdomen between the three feet convex, forming three rounded or semicircular prominent lobes between them.

11. Pterocanium eucolpum, n. sp. (Pl. 73, fig. 4).

Dictyopodium eucolpum, Haeckel, 1881, Prodromus et Atlas.

Shell about triangular-prismatic, with two deep strictures, smooth. Length of the three joints = 1 : 3 : 3, breadth = 1 : 3 : 4. Cephalis subspherical, with a conical, oblique horn of the same length. Thorax inflated, with three hemispherical swellings between the three crests, and with subregular, hexagonal pores. Abdomen longer, with much smaller, irregular, roundish pores, forming three broad, convex lobes between the three feet. (In the figured specimen the lobes were not fully developed, and extremely thin below the line parallel to the edge. In another specimen, found afterwards in the same locality, the three lobes were much larger, semicircular, and reached almost to the basal plane of the ends of the feet by reason of their convexity.) Feet strong, with slightly convex back, divergent.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.1; breadth, a 0.03, b 0.09, c 0.12.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

12. Pterocanium bicorne, n. sp. (Pl. 73, fig. 5).

Dictyopodium bicorne, Haeckel, 1881, Prodromus et Atlas.

Shell nearly three-sided pyramidal, slender, smooth. Length of the three joints = 1 : 2 : 2, breadth = 1 : 4 : 4. Cephalis hemispherical, with two oblique, conical horns of nearly equal length. Thorax nearly hemispherical, with slightly prominent crests, and with subregular, hexagonal pores. Abdomen of about the same length, with much smaller, irregular, roundish pores, forming three convex, nearly circular lobes between the three large divergent feet. These are slender, three-sided pyramidal, longer than the shell, fenestrated at the thickened base, with some rows of larger pores; their back is slightly concave.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.04; breadth, a 0.02, b 0.08, c 0.09.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

13. Pterocanium trilobum, Haeckel.

Dictyopodium trilobum, Haeckel, 1882, Monogr. d. Radiol., p. 340, Taf. viii. figs. 6-10.

Shell three-sided pyramidal, nearly tetrahedral, covered with conical spines. Length of the three joints = 1 : 4 : 2, breadth = 1 : 6 : 10. Cephalis hemispherical, with a large conical horn (as long as the thorax). Thorax tetrahedral, with little prominent crests. Abdomen forming three semicircular, convex lobes between the three feet, half as long as the thorax, with the same irregular, roundish pores. Feet slender, about as long as the shell, triangular, with convex back, strongly divergent, fenestrated at the inflated and thickened base. (Compare the special description of the living form and its soft body in my Monograph.)

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.03, b 0.12, c 0.2.

Habitat.—Mediterranean, Messina, surface.

Genus 589 Pterocodon,^[94] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three solid free lateral wings on the thorax, and numerous solid terminal feet around the mouth of the abdomen.

The genus Pterocodon differs from the closely allied Pterocorys, its ancestral form, in the development of numerous solid feet around the terminal mouth, similar to the terminal corona of Calocyclas.

1. Pterocodon campana, Ehrenberg.

Pterocodon campana, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 10. Pterocodon campana, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xix. fig. 1.

Shell slender, campanulate, subconical, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 2 : 3 : 5. Cephalis hemispherical, with a conical horn of twice the length. Thorax hemispherical, in the upper part with three divergent, conical horns, as long as the cephalis, and curved downwards. Abdomen with four transverse rows of large circular pores, increasing in size towards the mouth; the largest (undermost), five times as broad as the circular thoracic pores. Mouth not constricted, with a corona of twelve to fifteen divergent, conical feet.

Dimensions.—Length of the three joints, a 0.015, b 0.03, c 0.06; breadth, a 0.02, b 0.05, c 0.08.

Habitat.—Fossil in Barbados.

2. Pterocodon ornatus, n. sp. (Pl. 70, fig. 11).

Shell nearly ovate, with two deep strictures. Length of the three joints = 1 : 3 : 5, breadth = 1 : 5 : 7. Cephalis hemispherical, with a large oblique horn reaching half the length of the shell; three edges of the horn wing-shaped and dentated. Thorax hemispherical, in the middle zone with three conical wings, which are half as long as the thorax, and curved downwards. Pores hexagonal, roundish, twice as broad in the inflated abdomen as in the thorax. Mouth constricted, with a corona of from fifteen to eighteen conical, divergent, curved feet, similar to the thoracic wings.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.1; breadth, a 0.025, b 0.1, c 0.14.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Pterocodon favosus, n. sp.

Shell ovate, with two slight strictures. Length of the three joints = 1 : 2 : 2, breadth = 2 : 4 : 4. Cephalis hemispherical, with a conical horn of twice the length. Three wings of the thorax equal to those of the preceding species. Pores regular, circular, hexagonally framed, of equal size in the thorax and abdomen. Mouth constricted, with a corona of nine straight, conical, nearly vertical feet.

Dimensions.—Length of the three joints, a 0.0025, b 0.05, c 0.05; breadth, a 0.05, b 0.09, c 0.1.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Genus 590. Dictyocodon,^[95] Haeckel, 1881, Prodromus, p. 435.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three latticed free lateral wings on the thorax, and numerous latticed terminal feet around the mouth of the abdomen.

The genus Dictyocodon, one of the most elegant among the Nassellaria, differs from the preceding Pterocodon in the fenestration of the three lateral wings of the thorax, and the numerous terminal feet of the abdomen. It may be derived from Dictyoceras by development of regular lattice-feet around the terminal mouth.

Subgenus 1. Dictyocodella, Haeckel.

Definition.—The three lateral lattice-wings arise from the thorax alone.

1. Dictyocodon annasethe, n. sp. (Pl. 71, fig. 11).

Shell with two deep strictures. Length of the three joints = 2 : 5 : 4, breadth = 1 : 5 : 6. Cephalis subspherical, with a very large, three-sided prismatic horn of three times the length, bearing at the base some smaller accessory spines. Thorax nearly conical, with three large, inflated, triangular lattice-wings, the upper edge of which (the cortinar rod) descends obliquely, and is larger than the thorax, ending in a spine. Abdomen inflated, subcylindrical, divided at the wide open mouth by nine deep incisions into nine large triangular feet. Network in the thorax and wings composed of small, regular, hexagonal pores, in the abdomen of three transverse rows of irregular, very large pores, which are surrounded and separated by bands of very small pores; in each foot one large pore and a marginal series of very small pores occur. I dedicate this wonderful species to the memory of my dear wife, Anna Sethe.

Dimensions.—Length of the three joints, a 0.04, b 0.1, c 0.08; breadth, a 0.03, b 0.1, c 0.12.

Habitat.—Indian Ocean; Cocos Islands (Rabbe), surface.

2. Dictyocodon carolotæ, n. sp. (Pl. 71, fig. 14).

Shell with two deep strictures. Length of the three joints = 1 : 3 : 7, breadth = 2 : 5 : 6. Cephalis hemispherical, with an oblique pyramidal horn of twice the length. Thorax subconical, in the upper half with three divergent, triangular wings of half the length, the upper edge of which is nearly horizontal, little curved. Abdomen nearly cylindrical; divided at the wide open mouth by nine deep incisions into nine triangular, vertical feet, about as large as the wings. Network very delicate, with regular, small, circular pores of equal size and very thin bars. I dedicate this elegant species to my dear mother, Charlotte Sethe.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.14; breadth, a 0.04, b 0.1, c 0.12.

Habitat.—Cape of Good Hope (Bleek), surface.

Subgenus 2. Dictyocodoma, Haeckel.

Definition.—The three lateral wings are prolonged from the thorax to the abdomen.

3. Dictyocodon palladius, n. sp. (Pl. 71, figs. 12, 13).

Shell with distinct collar, but evanescent lumbar stricture. Length of the three joints = 1 : 2 : 7, breadth = 1 : 3 : 8. Cephalis very small, with a large pyramidal horn of twice the length, bearing at its base some small, often branched, accessory spines. Thorax three-sided pyramidal, without external boundary prolonged into the large, inflated, gradually dilated abdomen. The internal boundary between the two is marked by a fenestrated, horizontal ring (not indicated in the figure). Three prominent, triangular, fenestrated wings arise from the base of the cephalic horn, and are prolonged nearly through the whole shell almost to the edge of the mouth; in its lower half they form three elevated fenestrated apophyses, the upper edge of which is nearly horizontal. Mouth divided by about twenty incisions into as many triangular, vertical, fenestrated feet. The network of the whole shell is very delicate, like fine gauze, composed of very small, regular, hexagonal pores.

Dimensions.—Length of the three joints, a 0.03, b 0.055, c 0.21; breadth, a 0.03, b 0.09, c 0.25.

Habitat.—Central Pacific, Station 271, surface.

4. Dictyocodon prometheus, n. sp.

Shell tower-shaped, very similar to the preceding species in form and fenestration, but more slender and different in the longer and three-sided prismatic abdomen. Length of the three joints = 1 : 1 : 8, breadth = 1 : 3 : 7. Cephalis with two large divergent horns of three times the length, which are united by interior prolongations with the basal central point, from which arise the upper edges of the three divergent wings; the ends of the latter are directed downwards. Mouth with a corona of about thirty irregular, triangular feet.

Dimensions.—Length of the three joints, a 0.03, b 0.03, c 0.025; breadth, a 0.03, b 0.08, c 0.2.

Habitat.—Tropical Atlantic, Station 347, surface.

Genus 591. Pleuropodium,^[96] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) without ribs in the thorax, but with three ribs enclosed in the abdomen, which are prolonged into three terminal feet.

The genus Pleuropodium, formerly confounded with Theopodium and Pterocanium, differs from these two closely allied ancestral genera in the localisation of the three lateral ribs, which have disappeared in the thorax and become limited to the abdomen. It is therefore intermediate between the former and the following Podocyrtis.

1. Pleuropodium charybdeum, Haeckel.

Pterocanium charybdeum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 43, Taf. vi. figs. 7-10. Podocyrtis charybdea, J. Müller, 1856, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 492.

Shell campanulate, armed with scattered, bristle-shaped spines, with sharp collar and slight lumbar stricture. Length of the three joints = 1 : 3 : 1, breadth = 1 : 4 : 5. Cephalis cupola-shaped, with a large prismatic, somewhat curved horn, half as long as the shell. Thorax hemispherical, spiny. Abdomen short and wide, three-sided prismatic, with three stout longitudinal ribs, which are prolonged into three slender, prismatic, nearly vertical, slightly curved feet, about as long as the shell. Pores irregular, roundish, of variable size.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.03; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Mediterranean (Messina, Nice, &c.), surface.

2. Pleuropodium cortina, n. sp.

Shell campanulate, smooth, with two distinct strictures. Length of the three joints = 1 : 4 : 2, breadth = 1 : 3 : 4. Cephalis subspherical, with a small, pyramidal, straight horn of the same length. Thorax pear-shaped, with regular, circular, hexagonally-framed pores. Abdomen three-sided pyramidal, with irregular, roundish pores and three prominent, stout, prismatic ribs, which are prolonged into three straight, divergent feet of the same length.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth a 0.025, b 0.06, c 0.08.

Habitat.—North Atlantic, Station 354, surface.

Genus 592. Podocyrtis,^[97] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three simple, terminal feet on the mouth of the abdomen, without lateral ribs or wings. Apex with a horn, which usually is simple.

The genus Podocyrtis, and the two following closely allied genera, differ from all the preceding Theopilida in the absence of lateral ribs or wings, and the possession of three free terminal feet, which arise directly from the peristome, or from the margin of the abdominal mouth. They may be derived from Pleuropodium by reduction and loss of the three piercing lateral ribs, the terminal free prolongations of which only remain. The genus Podocyrtis is one of the largest and most common among all Cyrtoidea, being rich mainly in fossil forms. Ehrenberg in his Polycystins of Barbados (1875, loc. cit., p. 80) enumerated not less than thirty-one species. Some of these are yet living, and occur in the Pacific Radiolarian ooze collected by the Challenger. Other new forms are to be added, so that the number of species described in the following pages amounts to forty-five. Many of these are cosmopolitan, or at least common and widely distributed. To facilitate study we may divide this large genus into four subgenera: in two of these the terminal feet are divergent, or nearly parallel; in the two others convergent. In each of these two groups the pores of the thorax and the abdomen are either nearly equal in size and form, or distinctly different, the abdominal pores being often much larger than the thoracic. The small cephalis bears constantly an apical horn, which is usually simple, rarely branched.

Subgenus 1. Podocyrtarium, Haeckel.

Definition.—Feet divergent (the distance between their ends being greater than that between their bases). Pores of the thorax and abdomen nearly equal in size and similar in form.

1. Podocyrtis tripodiscus, n. sp. (Pl. 72, fig. 4).

Shell nearly conical, gradually dilated from the apical to the basal part, with two slight strictures. Surface a little rough. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 6. Pores subregular, circular, quincuncially disposed, of nearly equal size in the conical thorax and the subspherical abdomen. Cephalis hemispherical, with smaller pores and a spindle-shaped spiny horn of twice the length. Feet cylindrical, as long as the abdomen, little divergent, their ends curved outwards and thickened into a papillate knob.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.08; breadth, a 0.03, b 0.07, c 0.11.

Habitat.—Central Pacific, Station 265 to 272, depth 2425 to 2925 fathoms.

2. Podocyrtis attenuata, Ehrenberg.

Podocyrtis attenuata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 5.

Shell nearly conical, gradually dilated from the apical to the basal part, with two slight strictures. Surface a little rough. Length of the three joints = 2 : 3 : 4, breadth = 2 : 4 : 5. Pores subregular, circular, equal, quincuncial. Cephalis subspherical, with a conical horn of twice the length. Feet cylindrical, as long as the abdomen, little divergent (sometimes as in the specimen figured, nearly parallel).

Dimensions.—Length of the three joints, a 0.015, b 0.03, c 0.04; breadth, a 0.02, b 0.04, c 0.05.

Habitat.—Fossil in Barbados.

3. Podocyrtis thyrsoceras, n. sp.

Shell slender, conical, smooth, very similar to Thyrsocyrtis rhizodon, Ehrenberg (1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 1), with two slight strictures, nearly of the same form and fenestration as in the preceding smaller species. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis subspherical, with a large cylindrical straight horn, which reaches the length of the abdomen, and is papillate in the distal half. Feet cylindrical, divergent, nearly as long as the whole shell, broadened and spinulated at the distal end.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.06; breadth, a 0.02, b 0.06, c 0.08.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

4. Podocyrtis conica, n. sp.

Shell conical, without external strictures, but with two internal septal rings. Surface papillate. Length of the three joints = 2 : 3 : 8, breadth = 3 : 6 : 10. Pores equal, subregular, circular, quincuncial. Cephalis hemispherical, with a thick conical horn of the same length. Feet conical, about as long as the thorax, divergent in the direction of the outline of the conical shell.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.08; breadth, a 0.03, b 0.06, c 0.1.

Habitat.—Cosmopolitan, Central Pacific, Stations 263 to 274; Tropical Atlantic, Station 348, in depths between 2350 and 2925 fathoms; also fossil in Barbados.

5. Podocyrtis corythæola, n. sp. (Pl. 72, fig. 2).

Shell ovate conical, with two deep strictures, and with rough surface. Length of the three joints = 2 : 5 : 8, breadth = 3 : 8 : 10. Cephalis hemispherical, thorny, with a strong oblique horn three times the length, which is armed with nine to twelve conical spines. Pores small, circular, of irregular size and distribution. Feet spindle-shaped, divergent, as long as the inflated abdomen.

Dimensions.—Length of the three feet, a 0.02, b 0.05, c 0.08; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Indian Ocean, Maldive Islands (Haeckel), surface.

6. Podocyrtis surena, n. sp. (Pl. 72, fig. 10).

Shell thin-walled, tower-shaped, smooth, with two deep strictures. Length of the three joints = 2 : 5 : 10, breadth = 3 : 10 : 11. Cephalis subspherical, with a bent conical horn, as long as the hemispherical thorax. Abdomen cylindrical. Pores subregular, circular, quincuncially disposed, and slightly larger in the abdomen. Feet with a thickened calf, nearly perpendicular, as long as the thorax; their distal ends little divergent, and forming a knob beset with small roundish tubercles.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.1; breadth, a 0.035, b 0.1, c 0.11.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

7. Podocyrtis conulus, n. sp.

Shell elongate, conical, rough, without external strictures, but with two internal septal rings. Length of the three joints = 3 : 4 : 15, breadth = 5 : 7 : 12. Cephalis hemispherical, with a thick pyramidal horn of the same length. Feet also pyramidal, divergent, of the same size as the horn. Pores irregular, roundish, of variable size. Abdomen very long.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.15; breadth, a 0.05, b 0.07, c 0.12.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms; also fossil in Barbados.

8. Podocyrtis tridactyla, n. sp.

Shell conical, with two slight strictures, smooth. Length of the three joints = 2 : 6 : 5, breadth = 4 : 5 : 6. Cephalis hemispherical, with a pyramidal horn of twice the length. Pores irregular, polygonal, of variable size. Feet as long as the abdomen, constricted in the middle, trilobed at the distal end; the middle lobe twice as large as the lateral lobes.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.05; breadth, a 0.04, b 0.05, c 0.06.

Habitat.—Indian Ocean, Madagascar, Rabbe.

Subgenus 2. Podocyrtecium, Haeckel.

Definition.—Feet divergent (the distance between their ends being greater than that between their bases). Pores of the thorax and abdomen of different form or size.

9. Podocyrtis prismatica, n. sp. (Pl. 72, fig. 1).

Shell conical, rough, with two distinct strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 5. Cephalis subspherical, with a curved conical horn of twice the length. Thorax and abdomen together nearly hemispherical. Pores small, regular, circular, quincuncial, twice as large in the abdomen as in the thorax. Feet very large, twice as long as the whole shell, divergent, bent outwards, prismatic, with strong prominent edges.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.06; breadth, a 0.02, b 0.04, c 0.1.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

10. Podocyrtis brevipes, Ehrenberg.

Podocyrtis brevipes, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 6.

Shell conical, smooth, with two slight strictures. Length of the three joints = 2 : 3 : 6, breadth = 2 : 5 : 9. Cephalis subspherical, with a conical horn of the same length. Pores regular, circular, quincuncial, three times as broad in the abdomen as in the thorax. Feet short, triangular, divergent, as long as the horn. (The specimen figured by Ehrenberg was incomplete, one foot and the horn being broken off.)

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.06; breadth, a 0.02, b 0.05, c 0.09.

Habitat.—Fossil in Barbados.

11. Podocyrtis divergens, n. sp. (Pl. 72, fig. 6).

Shell slender, subconical, thick-walled, with two distinct strictures. Length of the three joints = 2 : 5 : 7, breadth = 4 : 8 : 10. Cephalis hemispherical, with a large, oblique, prismatic horn three times the length, and a small divergent by-horn at its base. Thorax hemispherical, rough, with regular, circular, quincuncial pores. Abdomen cylindrical, thorny, with larger circular pores of subregular disposition, two to three times as broad as those of the thorax. Feet conical, horn-like, bent, as long as the abdomen; strongly divergent in the distal half.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.07; breadth, a 0.04, b 0.08, c 0.1.

Habitat.—Western Tropical Pacific, Station 220, depth 1100 fathoms.

12. Podocyrtis collaris, Ehrenberg.

Podocyrtis collaris, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvi. fig. 1.

Shell conical, with slight collar and deeper lumbar stricture. Length of the three joints = 1 : 4 : 4, breadth = 1 : 4 : 8. Cephalis hemispherical, with a small oblique horn of the same length. Pores regular, circular, quincuncial, four to six times as broad in the inflated abdomen as in the conical thorax. Feet short and slightly divergent, little longer than the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.08; breadth, a 0.03, b 0.08, c 0.16.

Habitat.—Fossil in Barbados.

13. Podocyrtis ventricosa, Ehrenberg.

Podocyrtis ventricosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvi. fig. 3.

Shell conical, with two deep strictures, thorny. Length of the three joints = 1 : 2 : 5, breadth = 1 : 4 : 8. Cephalis subspherical, with a small conical horn of the same length. Pores regular circular, quincuncial, four to six times as broad in the inflated abdomen as in the hemispherical thorax. (Pores much larger and less numerous than in the similar preceding species.) Feet broad and stout, triangular, divergent, as long as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.1; breadth, a 0.025, b 0.07, c 0.16.

Habitat.—Fossil in Barbados.

14. Podocyrtis flosculata, n. sp. (Pl. 72, fig. 9).

Shell conical, rough, as broad as long, with distinct collar, but obliterated lumbar stricture. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 7. Cephalis hemispherical, with a thick conical horn of the same length. Thorax truncate, conical, with small, circular, quincuncial pores. Abdomen inflated, with very large and remarkable regular, quincuncial pores; their inner edge circular, the outer six-lobed, the six lobes elegantly alternating with six short conical spines. Feet very coarse, equilateral triangular, half as broad as the thorax, little divergent.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

15. Podocyrtis centriscus, Ehrenberg.

Podocyrtis centriscus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xiv. fig. 2.

Shell conical, rough, about as high as broad, with two obliterated strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 4 : 7. Cephalis small, hemispherical, with a stout conical horn. Pores of the inflated abdomen irregular, roundish, very large, three occurring in the course of its length, five times as broad as the small, very numerous, regular, circular pores of the conical thorax. Feet S-shaped, as long as the abdomen, with the blunt end curved outwards.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.08, c 0.14.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms; fossil in Barbados.

16. Podocyrtis magnifica, n. sp. (Pl. 72, fig. 5).

Shell conical, spiny, a little longer than broad, with two distinct strictures. Length of the three joints = 1 : 2 : 5, breadth = 2 : 4 : 7. Cephalis hemispherical, with a large conical horn, which is as long as the abdomen, nearly scaly, and covered with short, simple, and bifid spines. Pores regular, circular, quincuncially disposed, four times as broad in the inflated abdomen as in the conical thorax. Spines of the former twice as large as those of the latter. Feet very long and slender, cylindrical, S-shaped, bent outwards at the thickened distal end, with a spindle-shaped papillate knob.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.1; breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Canary Islands, Lanzerote, Haeckel, surface.

17. Podocyrtis princeps, Ehrenberg.

Podocyrtis princeps, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiii. fig. 1. Podocyrtis princeps, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 32.

Shell conical, with two distinct strictures. Length of three joints = 1 : 2 : 5, breadth = 1 : 4 : 7. Cephalis subspherical, with a large cylindrical, vertical horn, longer than the whole shell. Pores regular, circular, quincuncial, in the inflated spiny abdomen very large (four to five in the course of its length), five times as broad as in the smooth conical thorax. Feet about as long as the shell, slightly bent, S-shaped, cylindrical.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.1; breadth, a 0.03, b 0.08, c 0.14.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms; fossil in Barbados.

18. Podocyrtis euceros, Ehrenberg.

Podocyrtis euceros, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xv. fig. 1.

Shell conical, campanulate, with two deep strictures. Length of the three joints = 1 : 3 : 6, breadth = 2 : 5 : 7. Cephalis hemispherical, with a large, cylindrical horn, nearly as long as the shell. Pores regular, circular, hexagonally framed, quincuncial, four times as broad in the papillated, inflated abdomen as in the hemispherical, smooth thorax. Feet short and broad, triangular, divergent, about as long as the thorax. (In the specimen figured by Ehrenberg, two feet were broken off).

Dimensions.—Length of the three joints, a 0.016, b 0.05, c 0.1; breadth, a 0.03, b 0.08, c 0.12.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, and Pacific Oceans, at many stations, and in various depths; fossil in Barbados.

19. Podocyrtis cristata, n. sp. (Pl. 72, fig. 7).

Shell conical-campanulate, thorny, with two deep strictures. Length of the three joints = 1 : 2 : 5, breadth = 2 : 4 : 7. Cephalis subspherical, with a large, oblique, little bent, conical horn, as long as the abdomen. Thorax hemispherical, papillate, with small, regular, circular pores. Abdomen inflated, with very large, circular pores, (three to four in its length), six times as broad as those of the thorax, and separated by hexagonal, serrated crests. Feet cylindrical, stout, S-shaped, slightly divergent, with a spherical papillate knob at the distal end.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.1; breadth, a 0.035, b 0.07, c 0.14.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

20. Podocyrtis schomburgkii, Ehrenberg.

Podocyrtis schomburgkii, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 22; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xiv. 7.

Shell ovate-conical, with two distinct strictures. Length of the three joints = 2 : 5 : 10, breadth = 3 : 8 : 12. Cephalis hemispherical, with a large, straight, conical horn as long as the abdomen. Thorax campanulate, smooth, with small, regular, circular pores. Abdomen inflated, papillate, with very large, regular, hexagonal pores (three to four in the course of its length), five times as broad as their bars and as the pores of the thorax. Feet as long as the abdomen, nearly parallel, slightly bent outwards at the conical distal end.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.1; breadth, a 0.03, b 0.08, c 0.12.

Habitat.—Fossil in Barbados.

21. Podocyrtis hexagonalis, n. sp.

Shell nearly ovate, slender, everywhere covered with a regular network of high, hexagonal, denticulated crests, separating the circular, funnel-shaped pores, which are twice as large in the subspherical abdomen as in the hemispherical thorax, between both of which are two deep strictures. Length of the three joints = 1 : 3 : 6, breadth = 2 : 5 : 6. Cephalis hemispherical, with a long and thin cylindrical, vertical horn, as long as the abdomen. Feet of the same length and form, nearly straight, slightly divergent.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.12; breadth, a 0.04, b 0.11, c 0.13.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

22. Podocyrtis ovata, n. sp.

Shell nearly ovate, papillate, without external strictures. Length of the three joints = 1 : 2 : 3, breadth = 2 : 4 : 5. Cephalis hemispherical, with a pyramidal horn half as long as the shell. Pores regular, circular, hexagonally framed, three times as broad in the inflated abdomen as in the conical thorax. Feet pyramidal, little bent, divergent, about as long as the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.08; breadth, a 0.05, b 0.095, c 0.12.

Habitat.—Mediterranean, Corfu, Haeckel, surface.

23. Podocyrtis urceolata, n. sp.

? Podocyrtis mitra, Bury, 1862, Polycystins of Barbados, pl. v. fig. 3.

Shell nearly ovate, smooth, with two deep strictures. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 5. Cephalis subspherical, with a stout, conical horn of the same length. Thorax flat, hemispherical, with four to six transverse rows of small circular pores. Abdomen urceolate, with four to five transverse rows of very large, subregular, hexagonal pores. Feet short and thick, bent outwards, as long as the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.15; breadth, a 0.05, b 0.1, c 0.13.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms; fossil in Barbados.

24. Podocyrtis ehrenbergii, Haeckel.

Podocyrtis amphiacantha, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvii. fig. 3.

Shell slender, ovate, smooth, with deep collar, but evanescent lumbar stricture. Length of the three joints = 1 : 3 : 2, breadth = 1 : 3 : 3. Cephalis subspherical, with a large conical horn, as long as the campanulate thorax. Abdomen nearly cylindrical. Pores irregular, roundish, two to four times as large in the abdomen as in the thorax. Feet conical, slender, divergent, nearly as long as the shell. (In the imperfect specimen figured by Ehrenberg, two spines were broken off.)

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.02, b 0.06, c 0.06.

Habitat.—North Pacific, Station 253, depth 3125 fathoms; fossil in Barbados.

25. Podocyrtis argulus, Ehrenberg.

Podocyrtis argulus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 2.

Shell slender, ovate, or subconical, with two deep strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 4. Cephalis hemispherical, with a small conical horn of the same length (broken off in the figure of Ehrenberg). Pores regular, circular, three times as broad in the inflated abdomen as in the campanulate thorax. Feet spindle-shaped, slender, divergent, about as long as the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.1; breadth, a 0.03, b 0.07, c 0.1.

Habitat.—Tropical Atlantic, Station 247, depth 2530 fathoms; also fossil in Barbados.

Subgenus 3. Podocyrtidium, Haeckel.

Definition.—Feet convergent (the distance between their ends being smaller than that between their bases). Pores of the thorax and abdomen nearly equal in size and similar in form.

26. Podocyrtis papalis, Ehrenberg.

Podocyrtis papalis, Ehrenberg, Mikrogeol., Taf. xxxvi. fig. 23; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xv. fig. 6.

Shell ovate, smooth, without external stricture. Length of the three joints = 1 : 3 : 1, breadth = 1 : 3 : 3. Cephalis ovate, with a stout pyramidal horn of twice the length. Thorax and abdomen with about thirty longitudinal, divergent ribs, separating the same number of longitudinal rows of regular, circular pores, the size of which increases gradually towards the base. Feet shovel-shaped (broad, triangular, with convex outer and concave inner side, the obtuse end being curved inwards), about as long as the short abdomen, only slightly convergent.

Dimensions.—Length of the three joints, a 0.04, b 0.12, c 0.04; breadth, a 0.04, b 0.12, c 0.11.

Habitat.—Fossil in Barbados.

27. Podocyrtis costata, n. sp.

Shell ovate, smooth, of the same form and structure as Podocyrtis papalis, but with two distinct strictures and different proportions. Length of the three joints = 1 : 3 : 6, breadth = 2 : 4 : 6. About thirty longitudinal ribs regularly alternating with rows of circular, regular pores. Feet as in Podocyrtis papalis.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.12; breadth, a 0.04, b 0.08, c 0.12.

Habitat.—Central Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms.

28. Podocyrtis mitrella, Ehrenberg.

Podocyrtis mitrella, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xv. fig. 3.

Shell ovate, smooth, nearly of the same form and structure as Podocyrtis papalis, but different in the proportions of the joints, in the much smaller, regular pores, and in the great breadth of the shovel-shaped, blunt, about semicircular feet. Length of the three joints = 2 : 9 : 4, breadth = 3 : 10 : 3. Cephalis subspherical, with a thick pyramidal horn of the same length. Slight collar, but no lumbar stricture.

Dimensions.—Length of the three joints, a 0.02, b 0.09, c 0.04; breadth, a 0.03, b 0.1, c 0.03.

Habitat.—Fossil in Barbados.

29. Podocyrtis mitra, Ehrenberg.

Podocyrtis mitra, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 20; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xv. fig. 4.

Shell ovate, conical, smooth, with two slight strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis with the horn (of equal length) conical. Pores regular, circular, in about twenty longitudinal rows, slightly increasing in size in the middle part of the abdomen. Feet shovel-shaped, blunt, slightly divergent, only as long as the cephalis.

Dimensions.—Length of the three joints, a 0.025, b 0.5, c 0.7; breadth, a 0.03, b 0.075, c 0.1.

Habitat.—Cosmopolitan; Mediterranean (Gibraltar), Canary Islands, Central Pacific, Stations 265 to 274, in different depths; also fossil in Barbados.

30. Podocyrtis argus, Ehrenberg.

Podocyrtis argus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvi. fig. 9.

Shell ovate, with two distinct strictures, smooth. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subconical, with a conical horn of the same length. Thorax campanulate. Abdomen inflated. Pores subregular, roundish, of nearly equal breadth, quincuncial. Feet shovel-shaped, triangular, nearly vertical, only as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.08; breadth, a 0.025, b 0.08, c 0.1.

Habitat.—Tropical Atlantic, Station 347, surface; fossil in Barbados.

31. Podocyrtis eulophos, Ehrenberg.

Podocyrtis eulophos, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiv. fig. 6.

Shell subconical, slender, with two slight strictures, smooth. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 6. Cephalis hemispherical, with a large, spindle-shaped, angular horn of twice the length. Thorax hemispherical. Abdomen truncate, conical. Pores subregular, roundish, in about twenty longitudinal rows, their breadth gradually increasing towards the base. Feet shovel-shaped, blunt, nearly vertical, only as long as the cephalis.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.16; breadth, a 0.05, b 0.08, c 0.14.

Habitat.—Fossil in Barbados.

32. Podocyrtis favosa, n. sp.

Shell ovate, with two slight strictures, and with honeycomb-like surface. Length of the three joints = 1 : 5 : 2, breadth = 2 : 6 : 5. Cephalis hemispherical, with a pyramidal horn of twice the length. Thorax hemispherical. Pores regular, circular, hexagonally framed, funnel-shaped, with high, prominent crests between them. Feet shovel-shaped, little convergent, triangular, as long as the abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.04; breadth, a 0.04, b 0.12, c 0.11.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

33. Podocyrtis fusiformis, n. sp.

Shell slender, nearly spindle-shaped, diminishing gradually from the broadest middle part (immediately above the lumbar septum) towards the two poles. Length of the three joints = 1 : 5 : 8, breadth = 2 : 6 : 5. Cephalis subspherical, with a large conical horn three times the length. Thorax and abdomen with twenty-four to thirty denticulated, longitudinal ribs, separating the same number of longitudinal rows of regular, circular pores. Instead of the lumbar stricture, a broad, internal septum occurs. Feet slender, straight, as long as the abdomen, only slightly convergent.

Dimensions.—Length of the three joints, a 0.03, b 0.1, c 0.16; breadth, a 0.05, b 0.12, c 0.1.

Habitat.—Indian Ocean, Madagascar (Rabbe) surface.

Subgenus 4. Podocyrtonium, Haeckel.

Definition.—Feet convergent (the distance between their ends being smaller than that between their bases). Pores of the thorax and abdomen different in size or form.

34. Podocyrtis pedicellaria, n. sp. (Pl. 72, fig. 8).

Shell conical, ovate, with two very slight strictures. Length of the three joints = 2 : 3 : 8, breadth = 2 : 4 : 8. Cephalis conical, with a pyramidal horn of the same length. Pores subregular, circular, quincuncially disposed, two to three times as broad in the smooth abdomen as in the rough, spinulate thorax. Feet as long as the thorax, shovel-shaped (broad, triangular, with convex outer and concave inner side, the free ends being curved inwards), only slightly convergent.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.16; breadth, a 0.05, b 0.09, c 0.16.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms.

35. Podocyrtis sinuosa, Ehrenberg.

Podocyrtis sinuosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xv. fig. 5. Podocyrtis sinuosa, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 33.

Shell slender, conical, with slight collar, but without lumbar stricture. Length of the three joints = 1 : 2 : 4, breadth = 1 : 2 : 4. Cephalis subspherical (in the figure of Ehrenberg broken off), with a pyramidal horn of the same length. Pores subregular, circular, four times as broad in the abdomen as in the thorax. Feet shovel-shaped, as long as the thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.03, b 0.06, c 0.12.

Habitat.—Fossil in Barbados.

36. Podocyrtis floribunda, n. sp.

Shell ovate, conical, with two very slight strictures. Length of the three joints = 2 : 3 : 6, breadth = 2 : 4 : 7. Between twenty-four to thirty longitudinal, denticulated ribs lie the same number of subregular pores, which are flower-like, lobed, or rosette-shaped, and two to three times as large in the abdomen as in the thorax. Feet shovel-shaped (as in the similar Podocyrtis pedicellaria (Pl. 72, fig. 8).

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.12; breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms; also fossil in Barbados.

37. Podocyrtis scaphopodia, n. sp.

Shell conical, rough, with two slight strictures. Length of the three joints = 2 : 3 : 5, breadth = 2 : 4 : 8. Cephalis subspherical, with a pyramidal horn of twice the length. Pores subregular, circular, quincuncial, four times as large in the abdomen as in the thorax. Feet short and broad, triangular, shovel-shaped, with convergent ends. This species is similar to Podocyrtis brevipes, but differs in the form and size of the horn and of the feet.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.05; breadth, a 0.02, b 0.04, c 0.08.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

38. Podocyrtis lithoconus, n. sp. (Pl. 72, fig. 3).

Shell conical, thick-walled, smooth, with two slight strictures. Length of the three joints = 2 : 3 : 6, breadth = 2 : 4 : 7. Cephalis hemispherical, with a spindle-shaped horn of the some length. Pores subregular, circular, two to four times as broad in the abdomen as in the thorax. Feet triangular, shovel-shaped, nearly vertical, as long as the cephalis.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

39. Podocyrtis ampla, Ehrenberg.

Podocyrtis ampla, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 7.

Shell conical, thick-walled, with distinct collar, but without lumbar stricture. Length of the three joints = 1 : 4 : 5, breadth = 1 : 6 : 7. Cephalis hemispherical, with a large conical horn, as long as the thorax. Pores regular, circular, quincuncial, three times as broad in the rough abdomen as in the smooth thorax. Feet very small, shovel-shaped, only as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.1; breadth, a 0.03, b 0.12, c 0.14.

Habitat.—North Atlantic (Florida); also fossil in Barbados.

40. Podocyrtis nana, Ehrenberg.

Podocyrtis nana, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvii. fig. 2.

Shell conical, thorny, with two distinct strictures. Length of the three joints = 1 : 3 : 3, breadth = 2 : 5 : 6. Cephalis hemispherical, with a large cylindrical horn, nearly as long as the shell. Pores in the abdomen irregular, roundish, two to four times as broad as the regular, circular, quincuncial pores of the thorax. Feet very small, shovel shaped, scarcely as long as the cephalis.

Dimensions.—Length of the three joints, a 0.01, b 0.03, c 0.03; breadth, a 0.02, b 0.05, c 0.06.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms; also fossil in Barbados.

41. Podocyrtis lyæa, Haeckel.

Thyrsocyrtis lyæa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii, fig. 3.

Shell ovate, conical, with two deep strictures. Length of the three joints = 2 : 5 : 8, breadth = 3 : 8 : 9. Cephalis hemispherical, with a large conical horn, which is spinulate, scaly, and as long as the abdomen. Pores subregular, circular, two to four times as broad in the smooth abdomen as in the spiny thorax. Feet very short and broad, shovel-shaped, scarcely as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.08; breadth, a 0.03, b 0.08, c 0.09.

Habitat.—Fossil in Barbados.

42. Podocyrtis bromia, Haeckel.

Thyrsocyrtis bromia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 2.

Shell ovate, thorny, with two distinct strictures. Length of the three joints = 2 : 5 : 5, breadth = 3 : 8 : 9. Cephalis subspherical, with a large conical horn, which is half as long as the shell, and spirally dentated in the distal half. Thorax conical, spinulate, with regular, circular, quincuncial pores. Abdomen tuberculate, with a small number of very large irregular pores. Feet short, shovel-shaped, nearly vertical, as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.05; breadth, a 0.03, b 0.08, c 0.09.

Habitat.—Fossil in Barbados.

43. Podocyrtis sphærogaster, n. sp.

Shell inversely ovate, with two deep strictures. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 7. Cephalis hemispherical, with a slender, slightly bent horn, as long as the abdomen. Thorax hemispherical, spinulate. Abdomen nearly spherical, with much constricted mouth. Pores subregular, circular, hexagonally framed. Feet slender, cylindro-conical, about as long as the shell, with outer convexity, distinctly convergent.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

44. Podocyrtis tripus, Haeckel.

Podocyrtis bicornis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 8. ? Podocyrtis dipus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 83, Taf. xii. Fig. 11.

Shell conical, rough, with two deep strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 5. Cephalis subspherical, with a large, oblique, conical horn (sometimes with a small accessory horn at its base). Thorax hemispherical, with subregular, circular, small, quincuncial pores. Abdomen campanulate, with a small number (about twenty) of very large, irregular, polygonal pores. Feet conical, small, as long as the thorax, slightly convergent or nearly vertical.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.03, b 0.06, c 0.1.

Habitat.—Fossil in Barbados.

45. Podocyrtis triacantha, Ehrenberg.

Podocyrtis triacantha, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xiii. fig. 4.

Shell conical, rough, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 6. Cephalis hemispherical, with a very large conical horn, nearly as long as the whole shell. Thorax campanulate, densely spinulate, with very small, regular, circular, quincuncial pores. Thorax inflated, with very large, irregular, roundish, pores (three to four in the course of its length), five to ten times as broad as those of the thorax. Feet slender and thin, subcylindrical, as long as the abdomen, divergent in the proximal half, convergent and curved inwards in the distal half.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.04, b 0.08, c 0.12.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

Genus 593. Thyrsocyrtis,^[98] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three branched terminal feet on the mouth of the abdomen, without lateral ribs or wings. Apex with a horn, which usually bears lateral spines.

The genus Thyrsocyrtis differs from the preceding Podocyrtis, its ancestral form, in the ramification of the three terminal feet, which in the latter genus remain simple.

1. Thyrsocyrtis rhizodon, Ehrenberg.

Thyrsocyrtis rhizodon, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, Taf. xii. fig. 1.

Shell slender, conical, smooth, with two distinct strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with a large cylindrical horn, reaching half the length of the shell, and papillate in the distal half. Pores nearly equal, regular, circular, quincuncially disposed, small. Feet divergent, about half as long as the shell, broadened and forked at the distal end. (The fork incision is often much deeper, as in the figure given by Ehrenberg.)

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.06; breadth, a 0.03, b 0.06, c 0.08.

Habitat.—Fossil in Barbados.

2. Thyrsocyrtis arborescens, n. sp. (Pl. 68, fig. 9).

Shell nearly ovate, thorny, with a deep collar, but without lumbar stricture. Length of the three joints = 1 : 2 : 4, breadth = 2 : 3 : 4. Cephalis hemispherical, with a stout scaly or branched horn, half as long as the shell. Pores irregular, roundish, small, separated by spinulated crests, of slightly different sizes. Feet divergent, cylindrical, and as long as the thorax in the proximal half, irregularly branched or arborescent in the distal half, with ten to thirty blunt, thickened or papillate, terminal branches.

Dimensions.—Length of three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.04, b 0.06, c 0.08.

Habitat.—Central Pacific, Station 268, depth, 2900 fathoms.

3. Thyrsocyrtis furcata, n. sp.

Shell ovate, thorny, with two slight strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 3. Cephalis hemispherical, with a pyramidal smooth horn of twice the length. Pores of the thorax and abdomen nearly equal, regular, circular, quincuncial. Feet very broad, forked, about as long as the abdomen, much divergent; the outer fork-branch as long as the simple basal half of the foot, and twice as long as the inner or axial branch.

Dimensions.—Length of the three joints, a 0.03, b 0.03, c 0.09; breadth, a 0.04, b 0.06, c 0.09.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.

4. Thyrsocyrtis rhizopus, Haeckel.

Podocyrtis rhizodon, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 83, Taf. xv. fig. 2.

Shell pear-shaped, smooth, with two slight strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 5. Cephalis ovate, with a stout, sword-shaped horn of the same length. Pores regular, circular, twice as broad in the inflated abdomen as in the truncate, conical thorax. Feet cylindrical, parallel, vertical, straight, divided at the distal end into two short fork-branches.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.06, c 0.1.

Habitat.—Fossil in Barbados.

5. Thyrsocyrtis rhizopodium, n. sp. (Pl. 68, fig. 8).

Shell campanulate-conical, with deep collar, but without lumbar stricture. Length of the three joints = 3 : 4 : 10, breadth = 4 : 10 : 15. Cephalis subspherical, with a small conical horn of the same length. Pores regular, circular, quincuncial, three to four times as large in the inflated abdomen as in the truncate, conical thorax. Feet cylindrical, slightly divergent, about as long as the abdomen, S-shaped, bent outwards, irregularly branched in the distal half, with tuberculate terminal branches.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.1; breadth, a 0.04, b 0.1, c 0.15.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

6. Thyrsocyrtis radicata, Haeckel.

Podocyrtis radicata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiii. fig. 5.

Shell campanulate-conical, with two distinct strictures, length of the three joints = 1 : 2 : 4, breadth = 1 : 4 : 6. Cephalis subspherical, with a small conical horn of half the length. Pores regular, circular, quincuncial, four to five times as broad in the inflated, rough abdomen as in the campanulate, smooth thorax. Feet cylindrical, nearly as long as the whole shell, S-shaped, bent outwards, dilated and hand-shaped at the distal end, divided by three to five incisions in some irregular finger-like branches.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth a 0.03, b 0.08, c 0.12.

Habitat.—Fossil in Barbados.

7. Thyrsocyrtis trifida, n. sp.

Shell campanulate-conical, thorny, with two slight strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 5. Cephalis subspherical, with a short pyramidal horn of the same length. Pores regular, circular, hexagonally framed, twice as broad in the inflated spiny abdomen as in the rough, campanulate thorax. Feet very large, as long as the shell, cylindrical in the proximal simple half, in the distal half broadened and cleft into three large, irregularly lobed branches, two shorter lateral, and one longer abaxial branch; the latter forms the prolongation of the proximal half. The outer straight edges of the three diverging feet correspond to the edges of a three-sided pyramid.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.09; breadth, a 0.03, b 0.09, c 0.15.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 594. Dictyopodium,^[99] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three latticed terminal feet on the mouth of the abdomen, without lateral ribs or wings. Apex with a horn.

The genus Dictyopodium differs from the two preceding ancestral genera in the fenestration of the three terminal feet, which in Podocyrtis are simple, in Thyrsocyrtis branched, but not latticed.

1. Dictyopodium eurylophus, Ehrenberg.

Dictyopodium eurylophus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xix. fig. 4.

Shell campanulate-conical, thorny, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with a stout angular horn of twice the length, which at the apex is broadened and divided into some spines. Pores in the hemispherical thorax and in the truncate, conical abdomen of nearly equal size, small, subregular, circular (in the abdomen sometimes more irregular and unequal). Feet as long as the abdomen, arising from it with triangular base, diverging, fenestrated throughout the entire length.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.08; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms; fossil in Barbados.

2. Dictyopodium oxylophus, Ehrenberg.

Dictyopodium oxylophus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xix. fig. 5.

Shell subconical, smooth, with two slight strictures. Length of the three joints = 2 : 5 : 7, breadth = 3 : 8 : 10. Cephalis subspherical, with a small, conical, smooth horn of the same length. Pores irregular, polygonal, roundish, slightly larger in the abdomen than in the thorax. Feet as long as the thorax, arising from it with triangular base, diverging, fenestrated throughout the entire length. (The figures of this and the preceding species given by Ehrenberg are incomplete, having been drawn from spoiled specimens. In perfect specimens all the three feet are present and diverge in both species in the direction of the conical outline. The main difference between the two species is connected with the pores, which in Dictyopodium oxylophus are larger and more irregular, the two strictures are here not so deep.)

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.07; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Fossil in Barbados.

3. Dictyopodium scaphopodium, n. sp. (Pl. 73, fig. 8).

Shell campanulate, conical, with two deep strictures. Length of the three joints = 1 : 2 : 6, breadth = 1 : 4 : 8. Cephalis hemispherical, with a conical, smooth horn of twice the length. Thorax hemispherical, rough, with small, regular, circular pores. Abdomen inflated and papillate, with very large, polygonal or roundish pores (eight to ten times as broad as the thoracic pores). Feet divergent, nearly as long as the shell, S-shaped, bent outwards, solid and cylindrical in the proximal half, shovel-shaped and fenestrated in the distal half.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.025, b 0.08, c 0.16.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

4. Dictyopodium cothurnatum, Haeckel.

Podocyrtis cothurnata, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. B. 21; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xiv. fig. 1. Anthocyrtis cothurnata, Haeckel, 1862, Monogr. d. Radiol., p. 310.

Shell subconical, rough, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 5. Cephalis hemispherical, with a very large cylindrical, vertical horn, about as long as the whole shell. Thorax conical, rough, with small, regular, circular pores. Abdomen inflated, with very large, roundish pores (four to five in the course of its length), six to eight times as large as the thoracic pores. Feet nearly vertical, only slightly divergent, S-shaped, bent, as long as the abdomen, cylindrical; at the distal end shovel-shaped and fenestrated (often much more than in Ehrenberg's figure).

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.1; breadth, a 0.03, b 0.09, c 0.15.

Habitat.—Fossil in Barbados.

5. Dictyopodium thyrsolophus, n. sp. (Pl. 73, fig. 7).

Shell subconical, rough, with two slight strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis hemispherical, with an elegant horn, which is half as long as the shell, spindle-shaped and scaly on the distal third. Thorax hemispherical, with small, regular, circular pores. Abdomen inflated, papillate, with regular, circular pores, three times as large as the thoracic pores (five to six in the course of its length). Feet slightly divergent, cylindrical, about as long as the shell, shovel-shaped and fenestrated (with a prominent middle rib) at the distal end.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.04, b 0.1, c 0.18.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Subfamily 2. Theoperida, Haeckel, 1881, Prodromus, p. 436.

Definition.—Podocyrtida with the basal mouth of the shell fenestrated (vel Tricyrtida triradiata clausa).

Genus 595. Lithornithium,^[100] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with three solid lateral wings on the thorax.

The genus Lithornithium has an ovate or spindle-shaped shell, with two distinct strictures, and tapering towards both poles. The abdomen is simple, whilst the cephalis bears an apical horn, and the thorax three free, lateral, solid, divergent wings. It may be derived from Pterocorys by development of a terminal lattice-plate closing the mouth.

1. Lithornithium ciconia, n. sp. (Pl. 67, fig. 3).

Shell nearly spindle-shaped, with two indistinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 3. Cephalis ovate, with a large pyramidal spine of twice the length. Thorax three-sided pyramidal with three pyramidal wings of the same length, the broad triangular bases of which occupy the whole length of the thoracic edges. Abdomen inversely ovate (in the figured specimen broken off, in another specimen, found afterwards, completely closed at the distal end). Pores very small, regular, circular, of equal size.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.06, c 0.06.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

2. Lithornithium falco, n. sp. (Pl. 67, fig. 1).

Shell nearly ovate, with two sharp strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 3. Cephalis hemispherical, with a conical spine of the same length. Thorax subspherical, with three conical wings of half the length, little curved, arising with broad triangular base from the upper half of the thorax. Abdomen inversely conical. Pores irregular, roundish, of different sizes.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.07; breadth, a 0.03, b 0.08, c 0.06.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Lithornithium trochilus, n. sp. (Pl. 67, fig. 4).

Shell nearly spindle-shaped, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 2. Cephalis hemispherical, with a thin curved horn of the same length. Cephalis subovate, with three thin curved wings of half the length, arising with broad base from its upper half. Abdomen ovate. Pores subregular, circular, of slightly different sizes.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.06; breadth, a 0.02, b 0.05, c 0.04.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

4. Lithornithium foveolatum, Ehrenberg.

Lithornithium foveolatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iv. fig. 7.

Shell subovate, with two distinct strictures. Length of the three joints = 2 : 4 : 3, breadth = 3 : 5 : 4. Cephalis hemispherical, with a short conical spine of the same length. Thorax subspherical, with three broad triangular wings of half the length arising from its lower half. Abdomen subconical. Pores small, regular, circular, of nearly equal size.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.03; breadth, a 0.03, b 0.05, c 0.04.

Habitat.—Fossil in Barbados.

5. Lithornithium fringilla, n. sp. (Pl. 67, fig. 2).

Shell ovate, with two slight strictures. Length of the three joints = 4 : 7 : 4, breadth = 3 : 7 : 5. Cephalis ovate, with a pyramidal spine of the same length Thorax subconical, with three stout conical, curved wings of half the length, arising from its lower third (immediately above the girdle). Abdomen inversely campanulate. Pores subregular, circular, of equal size.

Dimensions.—Length of the three joints, a 0.04, b 0.07, c 0.04; breadth, a 0.03, b 0.07, c 0.05.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

6. Lithornithium hirundo, Ehrenberg.

Lithocampe hirundo, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 65. Lithornithium hirundo, Ehrenberg, 1854, Mikrogeol., Taf. xix. fig. 53.

Shell nearly ovate, with two deep strictures. Length of the three joints = 2 : 6 : 4, breadth = 2 : 7 : 5. Cephalis hemispherical, with an oblique, conical horn of twice the length. Thorax hemispherical, with three long, angular, little divergent wings of twice the length, which are S-shaped, curved, and arise from its lower third, immediately above the girdle. Abdomen inversely conical. Pores irregular, roundish, of different sizes. In the figure of Ehrenberg the abdomen is broken off; in a specimen from Caltanisetta, with somewhat shorter and broader wings, I found it complete.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.02, b 0.07, c 0.05.

Habitat.—Fossil in Tertiary rocks of the Mediterranean (Ægina, Greece; Caltanisetta, Sicily).

Genus 596. Sethornithium,^[101] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with three latticed lateral wings on the thorax.

The genus Sethornithium differs from the preceding Lithornithium, its ancestral form, only in the fenestration of the three thoracic wings, and bears therefore to it the same relation that Dictyoceras exhibits to Pterocorys.

1. Sethornithium dictyopterum, n. sp. Pl. 68, fig. 14.

Shell ovate, with two slight strictures. Length of the three joints = 2 : 4 : 3, breadth = 1 : 5 : 4. Cephalis ovate, with a pyramidal horn of twice the length. From the middle part of the thorax arise three broad, triangular, latticed wings of about the same length, the distal end of each of which is curved downwards. Abdomen inversely conical. Pores regular, circular. (Similar to Lithornithium fringilla, Pl. 67, fig. 2, but with much larger wings, which in the greater part are fenestrated.)

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.06; breadth, a 0.02, b 0.1, c 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 597. Theopera,^[102] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with three lateral wings, beginning from the sides of the thorax and prolonged into the sides of the abdomen.

The genus Theopera differs from the two preceding genera in the greater extension of the three lateral wings, which are prolonged from their original base, the thorax, into the inversely conical abdomen. It has therefore an intermediate position between the preceding and the following genera. It differs from the similar Pterocanium and Theopodium in the closure of the constricted and fenestrated mouth.

1. Theopera prismatica, n. sp. (Pl. 67, fig. 7).

Rhopalocanium prismaticum, Haeckel, 1879, Atlas, pl. lxvii. fig. 7.

Shell three-sided prismatic, with three broad and long hyaline wings, which are prolonged from the collar stricture almost to the basal end, with three parallel edges. Length of the three joints = 2 : 8 : 10, breadth = 3 : 9 : 8. Cephalis hemispherical, with a conical horn of the same length. Thorax subspherical; abdomen inversely ovate; pores of both small, regular, circular, of equal size.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.1; breadth, a 0.03, b 0.09, c 0.08.

Habitat.—South Atlantic, Station 332. depth 2200 fathoms.

2. Theopera pyramis, Haeckel.

Rhopalocanium sp., Bury, 1862, Polycystins of Barbados, pl. xvii. fig. 8.

Shell three-sided pyramidal, with three broad and long hyaline wings, which are prolonged from the collar stricture almost to the basal end, with three diverging edges. Length of the three joints = 3 : 8 : 11, breadth = 4 : 8 : 9. Cephalis subspherical, with a conical horn of the same length. Thorax hemispherical; abdomen inversely campanulate. Pores in the abdomen twice to three times as broad as in the thorax, subregular, circular. Differs from the preceding species mainly in the broader pyramidal form and the divergence of the wings.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.11; breadth, a 0.04, b 0.08, c 0.09.

Habitat.—Fossil in Barbados.

3. Theopera fusiformis (Pl. 67, fig. 5).

Shell nearly spindle-shaped, rough, with two slight strictures. Length of the three joints = 2 : 3 : 6, breadth = 2 : 5 : 4. Cephalis hemispherical, large, with an oblique conical horn of the same length. Thorax hemispherical; abdomen inversely conical. Pores irregular, roundish, of very different sizes. Three wings short, broad, diverging, triangular, and striated, embracing at the base the lumbar stricture, the lower third of the thorax and the upper third of the abdomen.

Dimensions.—Length of the three joints, a 0.04, b 0.06, c 0.12; breadth, a 0.045, b 0.1, c 0.08.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

4. Theopera luscinia, Haeckel.

Lithornithium luscinia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 78, Taf. iv. fig. 9.

Shell slenderly ovate, with distinct collar, but indistinct lumbar strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 5 : 5. Cephalis hemispherical, with a slender cylindrical horn of three times the length, bearing a spindle-shaped spinulate top (like a fir-cone). Pores subregular, circular, twice as broad in the abdomen as in the thorax. Three wings arising with broad triangular base, embracing the lower third of the thorax and the upper third of the abdomen, prolonged into three slender diverging spines, as long as the shell.

Dimensions.—Length of the three joints a 0.015, b 0.05, c 0.1; breadth, a 0.02, b 0.07, c 0.07.

Habitat.—Fossil in Barbados.

5. Theopera chytropus, n. sp. (Pl. 67, fig. 6).

Shell slender, ovate, with distinct collar, but indistinct lumbar stricture. Length of the three joints = 1 : 2 : 5, breadth = 1 : 3 : 3. Cephalis hemispherical, with a conical horn of the same length. Pores in the thorax and abdomen of similar shape, irregular, roundish. Three wings with broad triangular base attached at the upper half of the shell, in the lower half free, diverging, with a spinulate knob at the distal end.

Dimensions.—Length of the three joints, a 0.025, b 0.06, c 0.15; breadth, a 0.03, b 0.09, c 0.09.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms.

6. Theopera cortina, n. sp. (Pl. 67, fig. 8).

Shell slender, ovate, with distinct collar, but indistinct lumbar stricture. Length of the three joints = 1 : 2 : 6, breadth 1 : 4 : 4. Cephalis subspherical, with an elegant pyramidal horn of three times the length, bearing an ovate, spinulate knob. Pores subregular, circular, two or three times as large in the abdomen as in the thorax. The three wings are slightly elevated small ribs on the thorax, arise with broad, triangular, striated bases in the upper half of the abdomen, and are prolonged into three slender diverging feet, which are as long as the shell, and bear a spinulate, ovate knob at the distal end.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.13; breadth, a 0.03, b 0.08, c 0.08.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.

Genus 598. Rhopalocanium,^[103] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with three lateral wings on the sides of the inversely conical abdomen, which bears no vertical terminal horn on the basal apex.

The genus Rhopalocanium, and the closely allied Rhopalatractus which follows, differ from the preceding Theopera, their probable ancestral form, in the origin of the three lateral wings from the inversely conical abdomen, the thorax bearing no wings. The upper part of the wing bases, which arose formerly from the thorax, is here reduced and lost.

1. Rhopalocanium lasanum, n. sp. (Pl. 67, fig. 10).

Shell subovate, with two distinct strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with a conical, dimpled horn of twice the length. Thorax subconical, abdomen campanulate, both with irregular, circular pores. Three wings cylindrical, divergent, about as long as the shell, striated, with an ovate, dimpled knob at the distal end, their broad triangular base being attached to the upper half of the abdomen. (Form rather variable.)

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.09; breadth, a 0.03, b 0.09, c 0.12.

Habitat.—Central Pacific, Stations 263 to 268, depth 2650 to 3000 fathoms.

2. Rhopalocanium ornatum, Ehrenberg.

Rhopalocanium ornatum, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 9; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 82, Taf. xvii. fig. 8.

Shell nearly spindle-shaped, with two distinct strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 4 : 3. Cephalis hemispherical, with a stout, cylindrical horn of twice the length, bearing a dimpled cone. Thorax ovate, campanulate. Abdomen inversely conical. Pores subregular, circular, twice as large in the thorax as in the abdomen. Three wings compressed, slender, divergent, slightly longer than the abdomen, bearing an ovate, dimpled cone at their distal end, with the broad, triangular, striated base attached to the upper third of the abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.12; breadth, a 0.025, b 0.08, c 0.07.

Habitat.—Fossil in Barbados.

3. Rhopalocanium cortinium, n. sp.

Shell slender, ovate, nearly of the same form as, and with similar fenestration to that of Theopera cortina, (Pl. 67, fig. 8). It differs from the latter mainly by the absence of the three thoracic ribs, characteristic of Theopera. Length of the three joints = 1 : 2 : 6, breadth = 1 : 4 : 4. The three wings arise by a broad, triangular, striated base from the upper half of the abdomen, below the lumbar stricture. The cephalic horn and the three divergent wings are shorter, and at the distal end not so much thickened as in Theopera cortina.

Dimensions.—Length of the three joints, a 0.025, b 0.045, c 0.12; breadth, a 0.03, b 0.07, c 0.08.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

4. Rhopalocanium pythia, n. sp.

Rhopalocanium ornatum, Bury, 1862, Polycystins of Barbados, pl. vi. fig. 1.

Shell nearly ovate, with two deep strictures. Length of the three joints = 1 : 4 : 8, breadth = 1 : 4 : 4. Cephalis subspherical, with a conical horn of three times the length. Thorax inflated, abdomen inversely campanulate and prolonged into a short, conical, latticed tube. Pores subregular, circular. Three wings slender, as long as the abdomen, arising by a broader base from the uppermost part of the abdomen, their thickened end being curved inwards.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.15; breadth, a 0.03, b 0.08, c 0.07.

Habitat.—Fossil in Barbados.

5. Rhopalocanium delphicum, n. sp. (Pl. 67, fig. 9).

Shell nearly spindle-shaped, with two deep strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 3. Cephalis hemispherical, with a slender, conical, curved horn, as long as the hemispherical thorax. Abdomen inversely campanulate, prolonged into a short, conical, latticed tube. Pores subregular, circular. Three wings arising by a narrow base from the uppermost part of the abdomen, slender, cylindrical, S-shaped, curved, divergent, with a thick scaly appendix like a fir-cone at the distal end.

Dimensions.—Length of the three joints, a 0.025, b 0.07, c 0.14; breadth, a 0.03, b 0.09, c 0.08.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 599. Rhopalatractus,^[104] Haeckel, 1881, Prodromus, p. 437.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with three lateral wings on the sides of the inversely conical abdomen, which bears a vertical terminal horn on the basal apex.

The genus Rhopalatractus, one of the most remarkable forms of Tricyrtida, differs from the preceding Rhopalocanium, its ancestral form, in the production of a vertical, basal horn, which descends from the basal apex of the inversely conical abdomen, and is opposed to the upper apical horn of the cephalis. The shell becomes here, therefore, exquisitely spindle-shaped.

1. Rhopalatractus pentacanthus, n. sp. (Pl. 68, fig. 11).

Shell very thick-walled, with two sharp strictures. Length of the three joints = 1 : 6 : 8, breadth = 1 : 6 : 7. Cephalis hemispherical, with conical cavity, and a conical horn of twice the length. Thorax subspherical, separated from the abdomen by a deep lumbar stricture, with small, regular, circular, hexagonally-framed pores. Abdomen three-sided prismatic, with three strong, prominent, wing-shaped edges, which are slightly divergent towards the base, and prolonged into three pyramidal feet about as long as the thorax. Pores of the abdomen disposed in longitudinal rows, which are separated by denticulate crests. Abdominal base inversely pyramidal, and prolonged into a very large, cylindrical, basal, axial spine, nearly as long as the whole shell.

Dimensions.—Length of the three joints, a 0.02, b 0.12, c 0.15; breadth, a 0.03, b 0.11, c 0.14.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Rhopalatractus foveolatus, n. sp. (Pl. 68, fig. 10).

Shell slenderly ovate, thick-walled, with rough, dimpled surface. Length of the three joints = 1 : 3 : 5, breadth = 2 : 4 : 4. Cephalis hemispherical, with spherical cavity, and a thick, conical spine of the same length. Thorax subspherical, with subregular, circular pores. Abdomen inversely conical, with larger, irregular, roundish pores, prolonged at the distal end into a cylindrical, axial, basal spine of about half its length. From the middle part of the abdomen arise three lateral, conical feet, which are slightly curved and divergent downwardly, scarcely as long as the basal spine. All five spines are dimpled.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.1; breadth a 0.04, b 0.08, c 0.08.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Rhopalatractus fusiformis, n. sp.

Shell slender, spindle-shaped, nearly of the same form as in the preceding species. Length of the three joints = 1 : 2 : 6, breadth = 1 : 2 : 2. Cephalis subspherical, with a cylindrical horn three times the length. Pores subregular, circular, of equal breadth in the thorax and in the abdomen, which is prolonged into a cylindrical, axial, basal spine of the same length. From the upper third of the abdomen arise, from a broad triangular base, three conical wings of half the length, divergent and slightly curved inwards.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.15; breadth, a 0.03, b 0.06, c 0.06.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

4. Rhopalatractus fenestratus, n. sp. (Pl. 68, fig. 12).

Dictyatractus fenestratus, Haeckel, 1881, Prodromus et Atlas.

Shell nearly spindle-shaped, with two distinct strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 4 : 4. Cephalis hemispherical, with a large, club-shaped horn, nearly as long as the abdomen, sulcated by longitudinal ribs, which are elegantly denticulate in the distal half. Thorax subspherical. Abdomen subovate, prolonged into a pyramidal, axial, basal spine, half as long as the thorax. Pores subregular, circular. From the upper half of the abdomen arise three stout, lateral, diverged wings of about the same length, which are curved inwards and fenestrated both at the broad triangular base and at the thickened, three-edged distal end.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.12; breadth, a 0.03, b 0.08, c 0.08.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 600. Lithochytris,^[105] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theoperida (vel Tricyrtida triradiata clausa) with a three-sided pyramidal abdomen, the triangular base of which is prolonged at the three corners into three terminal feet.

The genus Lithochytris differs from all the other Theoperida in the absence of lateral wings and the possession of three divergent, terminal feet, which arise from the three corners of the three-sided pyramidal abdomen. It repeats, therefore, among the Tricyrtida, that characteristic formation which Sethochytris and Tetrahedrina represent among the Dicyrtida. Some species may be derived from Pterocanium, other species from Podocyrtis, by the development of a lattice-plate closing the terminal mouth.

Subgenus 1. Lithochytrodes, Haeckel.

Three feet of the abdomen solid, not fenestrated, representing external apophyses of the triangular shell-base.

1. Lithochytris cortina, n. sp. (Pl. 67, fig. 12).

Shell three-sided pyramidal, without external strictures, but with two internal girdles. Length of the three joints = 2 : 2 : 5, breadth = 3 : 4 : 6. Cephalis large, truncate-pyramidal, with nine deep divergent ribs (and nine longitudinal rows of pores between them), and with a stout pyramidal horn of half the length. The three prominent edges of the thorax and abdomen are prolonged over the base of the pyramid into three very stout, solid, subovate feet, about as long as the thorax.

Dimensions.—Length of the three joints, a 0.04, b 0.04, c 0.1; breadth, a 0.06, b 0.08, a 0.12.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Lithochytris pyriformis, n. sp. (Pl. 67, fig. 13).

Shell pyramidal, nearly pear-shaped, with two distinct strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 3. Cephalis large, pear-shaped, with a short pyramidal horn of half the length. Thorax and abdomen rounded, without prominent edges. Three basal feet pyramidal, solid, nearly vertical, as long as the thorax. Pores irregular, roundish, in the abdomen large, twice to three times as broad as in the thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.03, c 0.08; breadth, a 0.04, b 0.06, c 0.09.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

3. Lithochytris tripodium, Ehrenberg.

Lithochytris tripodium, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. iv. fig. 11.

Shell pyramidal, nearly pear-shaped, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 2 : 5. Cephalis with a horn of the same length, conical. Thorax and abdomen rounded, without prominent edges. Three basal feet conical, solid, strongly divergent, shorter than the thorax. Pores subregular, circular, twice as broad in the abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.03, b 0.05, c 0.1.

Habitat.—Fossil in Barbados.

Subgenus 2. Lithochytridium, Haeckel.

Definition.—Three feet of the abdomen hollow and fenestrated, representing direct protuberances or corner prolongations of the triangular shell-base.

4. Lithochytris galeata, n. sp. (Pl. 67, fig. 16).

Shell pyramidal, with two sharp strictures. Length of the three joints = 1 : 1 : 4, breadth = 1 : 2 : 4. Cephalis subspherical, with an oblique pyramidal horn of the same length. Thorax somewhat larger. Abdomen inflated, with three sharp, prominent edges, which are prolonged over the shell-base into three pyramidal, hollow, and fenestrated feet, longer than the thorax. Pores subregular, circular, twice as broad in the abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.025, c 0.1; breadth, a 0.025, b 0.05, c 0.1.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

5. Lithochytris pileata, Ehrenberg.

Lithochytris pileata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. v. fig. 3.

Shell three-sided pyramidal, with deep collar, but indistinct lumbar stricture. Length of the three joints = 2 : 2 : 9, breadth = 3 : 5 : 10. Cephalis with a conical horn of the same length, pear-shaped. Thorax very short and broad. Abdomen inflated, with three sharp, prominent edges, which are prolonged over the shell-base into three pyramidal, hollow and fenestrated feet, the lower edge of which is horizontal. Pores regular, circular, of equal size in the thorax and abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.09; breadth, a 0.03, b 0.05, c 0.1.

Habitat.—Fossil in Barbados.

6. Lithochytris lucerna, n. sp. (Pl. 67, fig. 14).

Shell three-sided pyramidal, with two indistinct strictures. Length of the three joints = 1 : 2 : 5, breadth = 2 : 3 : 8. Cephalis small, with a horn of the same length, conical. Thorax with subspherical cavity. Abdomen with three rounded, prominent edges, which are prolonged over the shell-base into three conical, hollow, and fenestrated feet, twice as long as the thorax, with a thick, pyramidal, terminal spine. Pores subregular, circular, of equal size in the thorax and abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.1; breadth, a 0.04, b 0.06, c 0.16.

Habitat.—South Pacific, Station 297, depth 1775 fathoms.

7. Lithochytris lanterna, n. sp. (Pl. 67, fig. 11).

Shell three-sided pyramidal, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis small, with a pyramidal slender horn of twice the length. Thorax with subspherical cavity. Abdomen with three sharp prominent edges, which are prolonged over the convex shell-base into three slender, prismatic, hollow, fenestrated feet, strongly divergent, twice as long as the thorax (seen in fig. 11 from the vaulted base). Pores circular, twice as broad in the abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.06, c 0.12.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

8. Lithochytris pyramidalis, Ehrenberg.

Lithochytris pyramidalis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. v. fig. 1.

Shell three-sided pyramidal, without external strictures, but with two internal transverse girdles. Length of the three joints = 1 : 2 : 6, breadth = 2 : 4 : 8. Cephalis with a short horn of half the length, conical. Cavity of the thorax subspherical. Abdomen with three rounded edges, prolonged over the concave base into three pyramidal, hollow, and fenestrated feet, twice as long as the thorax. Pores large, irregular, roundish.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.04, b 0.08, c 0.16.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; fossil in Barbados.

9. Lithochytris pteropus, n. sp. (Pl. 67, fig. 15).

Shell three-sided pyramidal, with two indistinct strictures, but with two broad, internal girdles. Length of the three joints = 2 : 2 : 6, breadth = 2 : 3 : 9. Cephalis with a small horn of half the length, pear-shaped. Thorax broader than long. Abdomen with three prominent, rounded edges, prolonged over the concave base into three conical, hollow, and fenestrated feet, twice as long as the thorax. Pores small, circular, irregular, in longitudinal series along the edges.

Dimensions.—Length of the three joints, a 0.04, b 0.04, c 0.12; breadth, a 0.04, b 0.06, c 0.18.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

10. Lithochytris vespertilio, Ehrenberg.

Lithochytris vespertilio, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. iv. fig. 10.

Shell three-sided pyramidal, with two indistinct strictures. Length of the three joints = 1 : 2 : 5, breadth = 2 : 3 : 10. Cephalis with a short horn of half the length, conical. Thorax inflated. Abdomen without prominent edges, divided in the lower half into three large, conical, hollow, and fenestrated feet, twice as long as the thorax. Pores small, irregular, roundish.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.1; breadth, a 0.04, b 0.06, c 0.2.

Habitat.—Fossil in Barbados.

Family LXVI. Phormocyrtida, n. fam.

Theophormida et Theophænida, Haeckel, 1881, Prodromus, pp. 436, 437.

Definition.—Tricyrtida multiradiata. (Cyrtoidea with a three-jointed shell, divided by two transverse constrictions into cephalis, thorax, and abdomen, with numerous, four to nine or more, radial apophyses.)

The family Phormocyrtida, composed of the Theophormida and Theophænida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is three-jointed, and bears numerous radial appendages (usually six or nine, sometimes more, rarely less, four or five). The two subfamilies differ in the shape of the terminal mouth, which is in the Theophormida a simple wide opening, in the Theophænida closed by a lattice-plate. The phylogenetic origin of the Phormocyrtida may be found either in the Podocyrtida or in the Anthocyrtida; they may be derived either from the former by interpolation of interradial, secondary apophyses between the three primary perradial apophyses; or from the latter by development of an abdomen.

The radial apophyses are originally radial ribs, which arise from the base of the cephalis on the collar stricture, run along the thorax and abdomen, and are often prolonged into terminal feet. Whilst in some forms the radial ribs are completely preserved in both joints, they are in other forms only partly visible (in the abdomen), and very often only their free terminal prolongations are preserved in the form of a corona of feet around the mouth of the thorax. This corona is either simple or double. Sometimes also a corona is developed on the lumbar stricture, between the thorax and abdomen. These apophyses exhibit a remarkable variety in the great subfamily Theophormida, with open mouth. In the small subfamily Theophænida, however, the apophyses appear as six or nine simple lateral wings on the abdomen.

The Theophormida are richly represented not only in the present seas, but also as fossils in Barbados, and numerous remarkable forms have been already described by Ehrenberg, in his genera Calocyclas and Cycladophora. Many Phormocyrtida belong to the most elegant and admirable forms of Radiolaria.

Synopsis of the Genera of Phormocyrtida.

I. Subfamily Theophormida. Terminal mouth of the abdomen a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Radial ribs enclosed in the wall of the shell, either the thorax or the abdomen.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Radial ribs in the thorax and the abdomen.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Abdomen flat, dilated, with a wide open mouth,	601. Theophormis.
						Abdomen ovate or cylindrical, with constricted mouth,	602. Phormocyrtis
				Radial ribs in the abdomen only.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Peristome with free terminal feet,	603. Alacorys.
						Peristome smooth, without free feet,	604. Cycladophora.
		No radial ribs in the shell wall. Peristome with a corona of terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Terminal corona simple.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Abdomen cylindrical or ovate, not dilated,	605. Calocyclas.
						Abdomen dilated, truncate, conical or discoidal,	606. Clathrocyclas.
				Corona of feet double.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Both coronas terminal,	607. Lamprocyclas.
						One corona, terminal, the other lumbar,	608. Diplocyclas.
II. Subfamily Theophænida.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Terminal mouth of the abdomen closed by a lattice-plate.			$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Six lateral wings,	609. Hexalatractus.
						Nine Lateral wings,	610. Theophæna.

Subfamily 1. Theophormida, Haeckel, 1881, Prodromus, p. 436.

Definition.—Phormocyrtida with the basal mouth of the shell open (vel Tricyrtida multiradiata aperta).

Genus 601. Theophormis,^[106] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with numerous radial ribs enclosed in the wall of the thorax and of the flat dilated abdomen; mouth of the latter wide open.

The genus Theophormis commences the series of the Theophormida, or the multiradiate Podocyrtida, as their oldest and simplest form. The three-jointed shell is flat, campanulate or hat-shaped, and pierced by four or more radial ribs, four of which are primary or perradial, the others secondary or interradial. Theophormis may be derived from the similar Sethophormis by development of a lumbar constriction, and a third joint or abdomen.

1. Theophormis callipilium, n. sp. (Pl. 70, figs. 1-3).

Shell flat, hat-shaped, with two sharp annular strictures. Cephalis large, flatly cap-shaped, with small, irregular, square meshes (fig. 3). The collar septum (fig. 2) is composed (as in the following species) of four crossed, thin, horizontal beams, each of which is inserted at the collar stricture by a three forked branch. From the centre of the collar stricture (in the common nodal point of the four beams) there arises a vertical, axial rod, which is inserted at the flat top of the cephalis by five branches (one central and four lateral). Length of the three joints = 1 : 3 : 2, breadth = 2 : 6 : 11. Thorax flat, campanulate, with four primary perradial ribs (prolongations of the four cortinar beams), and numerous (twenty to thirty) interpolated secondary ribs; four of these are in interradial (midway between the four primary ribs), and bisect the four large, semicircular, perradial meshes at the base of the thorax. Network of the thorax and abdomen subregular, with hexagonal meshes and thin bars. Abdomen flatly expanded, somewhat curved, like the brim of a hat, half as broad in the anterior (frontal) part as in the posterior (occipital) part, which is about as broad as the radius of the thorax. The twenty to thirty radial ribs of the abdomen are prolongations of the thoracic ribs, and are somewhat prominent at the margin of the peristome, which appears therefore elegantly indented.

Dimensions.—Length of the three joints, a 0.02 to 0.03, b 0.06 to 0.08, c 0.03 to 0.06; breadth, a 0.05 to 0.08, b 0.2 to 0.3, c 0.4 to 0.5.

Habitat.—Central Pacific, Station 271, surface.

2. Theophormis medusa, n. sp.

Shell flatly campanulate, with two distinct, annular strictures. Length of the three joints = 1 : 2 : 1, breadth = 2 : 5 : 8. Cephalis large, hemispherical. Thorax flatly conical, with four crossed ribs, opposite in pairs in two meridional planes, perpendicular one to another, and prolonged into the flat, nearly discoidal abdomen, which is half as broad as the thorax. The wall of the abdomen is pierced by eight radial ribs; four secondary ribs being interpolated between the four primary. Network of the entire shell very delicate, with regular, hexagonal meshes, and very thin bars. Peristome circular, not dentate.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.04; breadth, a 0.06, b 0.16, c 0.24.

Habitat.—Central Pacific, Station 266, surface.

3. Theophormis cruciata, n. sp.

Shell flat, campanulate, with two distinct annular strictures. Cephalis flat, cap-shaped, with irregular, square meshes. Thorax flat, conical, with hexagonal meshes. Abdomen flatly expanded, of half the breadth, with larger hexagonal meshes. Thorax and abdomen pierced by four stout radial ribs, lying opposite in pairs in two diameters, perpendicular one to another. No secondary or interradial ribs are interpolated between the four primary. Mouth truncate, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.05, b 0.18, c 0.25.

Habitat.—Central Pacific, Station 274, surface.

4. Theophormis senaria, n. sp.

Shell flat, hat-shaped, similar to Theophormis callipilium (Pl. 70, figs. 1-3), but with a different number and arrangement of the piercing radial ribs. The cephalis and its collar septum exhibit the same formation as in Sethophormis hexalactis, described above (p. 1245, Pl. 56, fig. 6.) The caudal and sternal ribs, which are opposed in the sagittal plane, are simple, whilst the two lateral ribs are forked. In the flat abdomen there are six secondary or interradial ribs, interpolated between the six primary or perradial ribs of the thorax. Delicate network with regular, hexagonal meshes.

Dimensions.—Length of the three joints, a 0.035, b 0.075, c 0.025; breadth, a 0.07, b 0.2, c 0.3.

Habitat.—Central Pacific, Station 272, surface.

Genus 602. Phormocyrtis,^[107] n. gen.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with numerous radial ribs enclosed in the wall of the thorax, and of the ovate or cylindrical abdomen; mouth of the latter constricted.

The genus Phormocyrtis differs from the preceding Theophormis in the ovate or cylindrical form of the abdomen, the mouth of which is more or less constricted. The former exhibits, therefore, the same relation to the latter that Sethamphora bears to Sethophormis among the Dicyrtida. Phormocyrtis may be derived directly either from Sethamphora by development of an abdomen, or from Pterocorys or Theopilium by multiplication of the three radial ribs.

1. Phormocyrtis carinata, n. sp.

Shell ovate, with two slight strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with a stout pyramidal horn of twice the length, and few very small pores. Pores in the campanulate thorax and the inflated abdomen regular, circular, small, and numerous. Six stout prominent ribs, beginning from the collar stricture, arise along the thorax and abdomen, and reach the constricted mouth, which is half as broad as the abdomen. (This species is very similar to Pterocorys carinata, from which it differs in the six complete radial ribs of the shell-wall.)

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.03, b 0.09, c 0.12.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

2. Phormocyrtis fastosa, Haeckel.

Eucyrtidium fastosum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ix. fig. 19.

Shell ovate, with two distinct strictures. Length of the three joints = 1 : 3 : 3, breadth = 1 : 5 : 6. Cephalis ovate, with a stout pyramidal horn of the same length, and numerous rather large pores. Pores in the campanulate thorax and the inflated abdomen much smaller, very numerous, regular, hexagonal. Along these two joints arise nine delicate, divergent ribs; these extend almost to the wide mouth, which is slightly constricted.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.08; breadth, a 0.02, b 0.1, c 0.12.

Habitat.—Indian Ocean (Zanzibar), depth 2200 fathoms, Pullen.

3. Phormocyrtis costata, n. sp. (Pl. 69, fig. 6).

Shell smooth, with sharp collar, but indistinct lumbar stricture. Length of the three joints = 2 : 5 : 5, breadth = 2 : 6 : 6. Cephalis conical, with a stout pyramidal horn of twice the length. Thorax and abdomen together nearly cylindrical, constricted towards both poles, with thirty to forty longitudinal ribs, which are nearly parallel, vertical in the middle part, and convergent towards both poles; alternate with the same number of longitudinal rows of regular, circular pores. Mouth with a broad, hyaline, only slightly constricted peristome.

Dimensions.—Length of the three joints, a 0.04, b 0.1, c 0.1; breadth, a 0.04, b 0.12, c 0.12.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

4. Phormocyrtis embolum, Haeckel.

Eucyrtidium embolum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 5.

Shell smooth, with sharp collar, but indistinct lumbar stricture. Length of the three joints = 3 : 7 : 10, breadth = 3 : 9 : 7. Cephalis subspherical, with a pyramidal horn of the same length. Thorax campanulate; abdomen inversely truncate, conical; both with sixteen to twenty longitudinal ribs, and alternate longitudinal rows of small circular pores, converging towards the two poles. Mouth truncate, with broad hyaline peristome.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.1; breadth, a 0.03, b 0.09, c 0.07.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; fossil in Barbados.

5. Phormocyrtis quadrata, n. sp.

Shell ovate, papillate, with two slight strictures. Length of the three joints = 2 : 3 : 13, breadth = 4 : 6 : 11. Cephalis hemispherical, small, with two divergent, pyramidal horns of twice the length. Along the hemispherical thorax and the ovate inflated abdomen run twenty-four to thirty curved ribs, converging towards the two poles, and alternate with the same number of longitudinal rows of circular, regular pores, disposed in ten to twelve transverse rows. Each pore with a square, elevated frame. Mouth constricted, only one-third as broad as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.13; breadth, a 0.04, b 0.06, c 0.11.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

6. Phormocyrtis longicornis, n. sp. (Pl. 69, fig. 15).

Theocorys longicornis, Haeckel, 1881, Prodromus et Atlas, loc. cit.

Shell slender, ovate, rough, with two slight strictures. Length of the three joints = 3 : 8 : 12, breadth = 4 : 10 : 11. Cephalis hemispherical, with a very large, cylindrical horn, about as long as the shell. Thorax hemispherical, with regular, circular, hexagonally-framed pores. Abdomen subcylindrical, with twenty to twenty-four nearly parallel undulate ribs, and alternate longitudinal rows of regular, circular pores. Mouth constricted, circular, about half as broad as the thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.12; breadth, a 0.04, b 0.1, c 0.11.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

Genus 603. Alacorys,^[108] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with numerous radial ribs in the abdomen, which are prolonged over the mouth into free feet.

The genus Alacorys and the following Cycladophora differ from the preceding two genera in the formation of the radial ribs, which arise from the lumbar stricture, and lie in the wall of the abdomen, but are absent on the thorax. The shell is usually large, more or less pyramidal or conical, with a wide open terminal mouth. The latter is in Cycladophora simply truncate, whilst in Alacorys it is surrounded by from four to twelve or more terminal feet, prolongations of the abdominal ribs. According to the different number of these (four, five, six, or more) some subgenera may be distinguished, as Tetralacorys, Pentalacorys, Hexalacorys, &c.

Subgenus 1. Tetralacorys, Haeckel, 1881, Prodromus, p. 436.

Definition.—Peristome armed with four feet, opposite in two meridian planes, which are perpendicular to one another.

1. Alacorys lutheri, n. sp. (Pl. 65, fig. 4).

Shell papillate, with distinct collar stricture. Length of the three joints = 3 : 6 : 6, breadth = 3 : 8 : 10. Cephalis subspherical, with a pyramidal horn of the same length. Thorax tuberculate, nearly hemispherical, with circular pores of very different sizes. From the margin of its wide open mouth descend four stout perradial ribs, which are forked at the distal end, and by communication of their fork-branches form the four large, pentagonal holes of the abdomen. From the middle of the lower margin of the holes descend four parallel, vertical, slender feet, about as long as the shell. This species is dedicated to the memory of the great Reformer, Martin Luther.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.06; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Alacorys tetracantha, Haeckel.

Podocyrtis tetracantha, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiii. fig. 2. ? Podocyrtis parvipes, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiv. fig. 5.

Shell rough, with distinct collar stricture. Length of the three joints = 1 : 3 : 5, breadth = 1 : 4 : 6. Cephalis subspherical, with a rudimentary conical horn. Thorax campanulate, with irregular, roundish pores of different sizes. Abdomen inflated, with a small number of very large irregular holes, intermingled with smaller roundish holes. From the margin of the wide open mouth descend, nearly vertically, four strong vertical feet, which are about as long as the shell, and slightly curved, with convex outlines. Podocyrtis parvipes of Ehrenberg seems to be only a mutilated specimen of this species.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.09; breadth, a 0.03, b 0.08, c 0.13.

Habitat.—Fossil in Barbados.

Subgenus 2. Pentalacorys, Haeckel, 1881, Prodromus, p. 436.

Definition.—Peristome armed with five feet, one of which is odd and occipital, the other four paired and lateral.

3. Alacorys pentacantha, Haeckel.

Podocyrtis pentacantha, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvii. fig. 1.

Shell rough, with slight collar stricture. Length of the three joints = 1 : 2 : 3, breadth = 1 : 4 : 6. Cephalis subspherical, with a rudimentary conical horn. Thorax campanulate, with subregular, circular, quincuncial pores. Abdomen wider, campanulate, with a small number of very large and irregular, roundish holes. From the peristome descend five stout conical feet, which are slightly curved and divergent, nearly as long as the shell.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.06; breadth, a 0.025, b 0.08, c 0.11.

Habitat.—Fossil in Barbados.

4. Alacorys bismarckii, n. sp. (Pl. 65, fig. 3).

Shell spiny, with distinct collar stricture. Length of the three joints = 1 : 4 : 5, breadth = 2 : 7 : 10. Cephalis hemispherical, with a very stout, dimpled, conical horn of the same length. Thorax campanulate, spiny, with regular, circular pores. Abdomen wider, campanulate, with larger conical spines, and a small number of irregular, roundish, very large holes. From the peristome descend, nearly vertically, five very large cylindrical feet, nearly twice as long as the shell; they are S-shaped, curved, spinulate in the distal half, and armed at the proximal base with two stout conical spines, the smaller of which is directed inwards, the larger curved upwards. Dedicated to Prince Otto von Bismarck, the Reconstructor of the German Empire.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.1; breadth, a 0.04, b 0.14, c 0.2.

Habitat.—Western Tropical Pacific (north of New Guinea), Station 220, depth 1100 fathoms.

Subgenus 3. Hexalacorys, Haeckel, 1881, Prodromus, p. 436.

Definition.—Peristome armed with six feet, three of which are primary or perradial (Podocyrtis), the three other alternate, secondary or interradial.

5. Alacorys friderici, n. sp. (Pl. 65, fig. 1).

Shell conical, rough, with sharp collar stricture. Cephalis subspherical, with a large, oblique, prismatic horn, twice the length. Thorax campanulate, with regular, circular pores (six to eight in its length). Abdomen wider, campanulate, with a small number of very large pores (three to four in the course of its length). Peristome with six very large divergent feet, which are about as long as the shell, cylindrical, irregularly curved. The specimen figured was observed living, with expanded pseudopodia. The central capsule exhibited four large pear-shaped lobes, filling up the shell-cavity; each contained an oil-globule in the thoracic part. The undivided cephalic part of the capsule enclosed a nucleus, from which four lobes protruded through the four collar pores into the thorax. Dedicated to Frederick the Great, the Royal Philosopher of Potsdam.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.08; breadth, a 0.04, b 0.09, c 0.14.

Habitat.—North Atlantic, Canary Islands, Lanzerote (Haeckel), surface.

6. Alacorys guilelmi, n. sp. (Pl. 65, fig. 2).

Shell thorny, with distinct collar stricture. Length of the three joints = 1 : 3 : 4, breadth = 2 : 5 : 8. Cephalis hemispherical, with a rudimentary conical horn. Thorax hemispherical, spiny, with regular, circular pores. Abdomen wider, campanulate, papillate, with a small number of very large circular holes. Peristome with six diverging feet, which are about as long as the shell, at the base conical, thickened, and at the distal end curved inwards, with a spinulate knob. Dedicated to the German Emperor, Wilhelm.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.08; breadth, a 0.03, b 0.1, c 0.16.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

7. Alacorys hexacantha, n. sp.

Shell thorny, with slight collar stricture. Length of the three joints = 2 : 5 : 7, breadth = 4 : 10 : 14. Cephalis flat, cap-shaped, with a rudimentary conical horn. Thorax campanulate, with regular, circular pores. Abdomen wider, campanulate, with a small number of very large polygonal pores. Peristome with six large divergent feet, which are longer than the shell, cylindrical, and slightly curved, in the proximal half convex, in the distal half concave.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.07; breadth, a 0.04, b 0.1, c 0.14.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

8. Alacorys hexapleura, n. sp.

Shell spiny, with distinct collar stricture. Length of the three joints = 2 : 10 : 8, breadth = 3 : 11 : 10. Cephalis hemispherical, large, hyaline, and thick-walled, with a very stout, conical horn of the same length. Thorax pear-shaped, with numerous, regular, circular pores and conical spines, the size of which increases gradually towards the deep, lumbar stricture. Abdomen truncate, conical, with irregular, roundish pores, and six very strong, straight, divergent ribs, prolonged into six short, conical feet.

Dimensions.—Length of the three joints, a 0.04, b 0.2, c 0.16; breadth, a 0.06, b 0.22, c 0.2.

Habitat.—Fossil in Barbados.

Subgenus 4. Octalacorys, Haeckel.

Definition.—Peristome armed with eight feet, four of which are primary or perradial (corresponding to those of Tetralacorys), the other four alternate, secondary, or interradial.

9. Alacorys aculeata, Haeckel.

Podocyrtis aculeata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xiii. fig. 3. Podocyrtis aculeata, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 34.

Shell spiny, with deep collar stricture. Length of the three joints = 2 : 5 : 8, breadth = 2 : 7 : 10. Cephalis subspherical, with a slender, conical horn of twice the length. Thorax campanulate, thorny, with regular, circular pores. Abdomen wider, campanulate, with a small number of very large, regular, hexagonal meshes, and stout spines in the nodal points. Peristome with eight strong conical feet, which are nearly parallel, little curved (convex at the outside), and sometimes all of the same size (equal to the length of the shell); at other times different, four larger alternating with four smaller feet.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.08; breadth, a 0.025, b 0.07, c 0.1.

Habitat.—Fossil in Barbados.

10. Alacorys octacantha, n. sp.

Shell spiny, with deep collar stricture. Length of the three joints = 2 : 8 : 6, breadth = 3 : 7 : 7. Cephalis ovate, with a short, conical horn. Thorax pear-shaped, spiny, with regular, circular pores, similar to Cycladophora erinaceus, Ehrenberg (1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. fig. 2). Abdomen truncate, conical, with irregular, roundish pores, and eight stout, straight, thorny, divergent ribs of equal size, which are prolonged into eight free, conical, spiny feet of the same length.

Dimensions.—Length of the three joints, a 0.04, b 0.16. c 0.12; breadth, a 0.06, b 0.14, c 0.14.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 5. Ennealacorys, Haeckel.

Definition.—Peristome armed with nine feet, three of which are primary or perradial, the other six secondary or interradial.

11. Alacorys enneacantha, n. sp.

Shell papillate, with slight collar stricture. Length of the three joints = 2 : 4 : 8, breadth = 3 : 6 : 9. Cephalis hemispherical, with a stout, conical horn of twice the length. Thorax campanulate, with subregular, circular pores, and small, conical papillæ. Thorax wider, campanulate, with circular pores, and conical papillæ of three times the size. Peristome with nine widely divergent, little curved, conical feet, about as long as the shell. Similar to Podocyrtis ventricosa, Ehrenberg (1875, loc. cit., Taf. xvi. fig. 3), different mainly in the feet.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.03, b 0.06, c 0.09.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

12. Alacorys gigas, n. sp.

Shell thorny, with distinct collar stricture. Length of the three joints = 1 : 4 : 2, breadth = 1 : 5 : 4. Cephalis ovate, with a short, conical horn of about half the length. Thorax campanulate, thorny, with small, regular, circular pores, very similar to Cycladophora gigas, Ehrenberg (loc. cit., 1875, p. 68, Taf. xviii. fig. 1). Abdomen truncate, conical, smooth, with irregular, roundish pores, and nine stout and straight, little divergent ribs, which are prolonged into nine cylindrical, pointed feet of the same length.

Dimensions.—Length of the three joints, a 0.05, b 0.2, c 0.1; breadth, a 0.05, b 0.25, c 0.2.

Habitat.—Fossil in Barbados.

Subgenus 6. Polyalacorys, Haeckel.

Definition.—Peristome with numerous (ten to twenty or more) prominent feet, three or four of which are primary and perradial, the others secondary and interradial.

13. Alacorys dodecantha, n. sp.

? Podocyrtis schomburgkii, var., Bury, 1862, Polycystins of Barbados, Taf. xii. fig. 3.

Shell smooth, with slight collar stricture. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 7. Cephalis ovate, with a conical horn of the same length. Thorax campanulate, with regular, circular pores. From its margin arise twelve stout, little curved, radial beams, which are widely divergent, and connected in the middle part by a transverse circular ring, so that the abdomen exhibits twelve large triangular holes, and at the peristome, alternating with these, twelve free conical feet of the same length.

Dimensions.—Length of the three joints, a 0.04, b 0.09, c 0.11; breadth, a 0.03, b 0.12, c 0.22.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms; also fossil in Barbados.

14. Alacorys carcinus, n. sp. (Pl. 74, fig. 9).

Calocyclas carcinus, Haeckel, 1879, Atlas, loc. cit. Podocyrtis schomburgkii, var., Bury, 1862, Polycystins of Barbados, pl. i. fig. 2; pl. xii. fig. 4.

Shell rough, with distinct collar stricture. Length of the three joints = 1 : 4 : 4, breadth = 2 : 6 : 6. Cephalis hemispherical, with a large, cylindrical, bent spine of three times the length. Thorax inflated, campanulate, with large, regular, circular pores. Abdomen truncate, conical, with three to four transverse rows of regular, square pores, produced by eighteen divergent, straight ribs, which are connected by three to four horizontal rings. Distal end of the ribs prolonged into eighteen slender, conical feet, which are about as long as the thorax and slightly curved inwards.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.08; breadth, a 0.05, b 0.12, c 0.12.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms; also fossil in Barbados.

15. Alacorys polyacantha, n. sp.

Shell spiny, with deep collar stricture. Length of the three joints = 3 : 9 : 10, breadth = 4 : 12 : 16. Cephalis hemispherical, with a stout conical horn of the same length. Thorax campanulate, with regular, circular pores and conical spines, increasing in size towards the deep lumbar stricture. Abdomen truncate, conical, with twenty to thirty divergent, straight ribs, which are connected by four to six transverse rings, and prolonged into free conical feet of half the length. Therefore four to six transverse rings of regular, square pores occur.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.1; breadth, a 0.04, b 0.12, c 0.16.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

16. Alacorys ornata, Haeckel.

Cryptoprora ornata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. v. fig. 8.

Shell ovate, smooth, without external strictures, but with two internal annular septa. Length of the three joints = 3 : 5 : 4, breadth = 3 : 6 : 5. Cephalis subspherical, partly enclosed by the uppermost part of the thorax, without horn, or with a small rudimentary horn. Pores subregular, circular, half as broad in the cephalis as in the two other joints. Thorax campanulate. Abdomen truncate, with eighteen to twenty-four parallel, vertical, longitudinal ribs, which are prolonged into slender, free, conical feet of the same length. (This remarkable species may be derived from Carpocanium by apposition of a third joint.)

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.04; breadth, a 0.03, b 0.06, c 0.05.

Habitat.—Fossil in Barbados.

Genus 604. Cycladophora,^[109] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with four to six or more radial ribs in the abdomen, the terminal mouth of which is truncate, without feet.

The genus Cycladophora differs from the preceding Alacorys, its probable ancestral genus, in the absence of free terminal feet, the radial ribs of the abdomen being connected by transverse beams throughout their whole length. The number of the regularly disposed ribs (four to six or more) may also here be used for the distinction of different subgenera.

Subgenus 1. Lampterium, Haeckel, 1881, Prodromus, p. 434.

Definition.—Abdomen with four radial ribs, opposite in pairs in two meridian planes, perpendicular one to another.

1. Cycladophora gœtheana, n. sp. (Pl. 65, fig. 5).

Shell shaped like a lantern, with two sharp strictures. Length of the three joints = 1 : 2 : 12, breadth = 1 : 4 : 7. Cephalis hemispherical, with a slender pyramidal horn of three times the length. Thorax twice as large, thorny, hemispherical, with regular, circular pores. Abdomen very long, nearly four-sided prismatic, with four superior smaller, and four inferior larger holes; the former separated by four short, divergent, perradial, the latter by four long, parallel, vertical, interradial bars. Mouth square, four-lobed. Dedicated to Wolfgang Goethe.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.24; breadth, a 0.03, b 0.07, c 0.1 to 0.14.

Habitat.—Central Pacific, Stations 265 to 269, depth 2550 to 2900 fathoms.

2. Cycladophora tetrapleura, n. sp.

Shell very similar to the preceding species, but differing in the following characters: Cephalis conical, with a horn of the same length. Thorax campanulate. Four ribs of the abdomen not parallel and vertical, but more or less divergent. Length of the three joints = 1 : 2 : 8, breadth = 1 : 2 : 4. Whole shell slender, pyramidal. Mouth square, four-lobed.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.24; breadth, a 0.03, b 0.06, c 0.12.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

3. Cycladophora lanterna, n. sp.

Shell very similar to the two preceding species, but differing in the following characters. Cephalis subspherical, with a thick, pyramidal horn of the same breadth, and three times the length. Thorax hemispherical, with circular, hexagonally-framed pores. Abdomen ovate, with four convex ribs, and twelve large holes, four superior smaller pentagonal, four intermediate very large, ovate, and four inferior, small, triangular holes. Mouth little constricted, nearly circular.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.22; breadth, a 0.025, b 0.08, c 0.11.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

Subgenus 2. Lamptidium, Haeckel.

Definition.—Abdomen with six radial ribs (three primary or perradial, and three alternate, secondary or interradial).

4. Cycladophora hexapleura, n. sp.

Lanterna chinensis, Bury, 1862, Polycystins of Barbados, pl. xiii. fig. 7.

Shell shaped like a lantern, with six sides and two sharp strictures. Length of the three joints = 1 : 2 : 8, breadth = 1 : 2 : 4. Cephalis hemispherical, with a conical spine of the same length. Thorax twice as large, hemispherical, with regular, circular pores. Abdomen nearly six-sided prismatic, with six descending, little curved ribs, and eighteen large holes between them; six superior holes interradial, ovate, six intermediate holes very large, perradial, ovate, six inferior holes triangular, interradial. Mouth six-lobed.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.16; breadth, a 0.03, b 0.06, c 0.1.

Habitat.—Fossil in Barbados.

5. Cycladophora pyramidalis, n. sp.

Podocyrtis sp., Bury, 1862, Polycystins of Barbados, pl. xii. fig. 2.

Shell slender, pyramidal, with six sides and two slight strictures. Length of the three joints = 1 : 4 : 12, breadth = 1 : 4 : 8. Cephalis subspherical, with a conical horn of twice the length. Thorax conical, with regular, circular pores. Abdomen truncate, pyramidal, with six strong, divergent, straight ribs, which are connected by five to six transverse, hexagonal rings; therefore six longitudinal rows of large, roundish, quadrangular meshes (four to five meshes in each row). Mouth hexagonal.

Dimensions.—Length of the three joints, a 0.025, b 0.1, c 0.3; breadth, a 0.03, b 0.1, c 0.2.

Habitat.—Fossil in Barbados.

6. Cycladophora spinosa, n. sp.

Shell spiny, with two deep strictures. Length of the three joints = 1 : 4 : 3, breadth = 1 : 5 : 4. Cephalis subspherical, with a stout conical horn of the same length. Thorax ovate, with regular, circular pores, and numerous conical spines. Abdomen truncate, conical, with irregular, roundish pores, and six strong, divergent ribs. Mouth circular.

Dimensions.—Length of the three joints, a 0.03, b 0.12, c 0.09; breadth, a 0.03, b 0.15, c 0.12.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; fossil in Barbados.

Subgenus 3. Lamptonium, Haeckel.

Definition.—Abdomen with nine radial ribs (three primary or perradial, and six secondary or interradial).

7. Cycladophora enneapleura, n. sp.

Shell spiny, with two sharp strictures. Length of the three joints = 1 : 5 : 3, breadth = 2 : 7 : 4. Cephalis hemispherical, with a conical horn of twice the length. Thorax campanulate, with regular, circular pores, and conical thorax. Abdomen cylindrical, with nine straight, parallel ribs, and irregular, roundish pores. Mouth circular. (Similar to Cycladophora gigas, Ehrenberg, 1875, loc. cit., Taf. xviii. fig. 1, but differing in the possession of nine abdominal ribs.)

Dimensions.—Length of the three joints, a 0.03, b 0.15, c 0.1; breadth, a 0.06, b 0.2, c 0.12.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

8. Cycladophora nonagona, n. sp.

Shell spiny, with two distinct strictures. Length of the three joints = 3 : 10 : 7, breadth = 2 : 9 : 8. Cephalis pear-shaped, with a stout pyramidal horn of the same length. Thorax pear-shaped, with regular, circular pores, and conical horns, increasing in size towards the base. Abdomen truncate, pyramidal, with nine straight, spinulate ribs, and nine even faces between them, with irregular, roundish pores. Mouth nonagonal.

Dimensions.—Length of the three joints, a 0.06, b 0.2, c 0.14; breadth, a 0.05, b 0.18, c 0.16.

Habitat.—Fossil in Barbados.

Subgenus 4. Cyclampterium, Haeckel.

Definition.—Abdomen truncate, conical or campanulate, with numerous (ten to twenty or more) divergent ribs. Mouth wide open, truncate.

9. Cycladophora pantheon, n. sp. (Pl. 68, fig. 3).

Shell dome-shaped, with slight collar and deep lumbar stricture. Length of the three joints = 1 : 6 : 5, breadth = 1 : 7 : 8. Cephalis small, with a conical horn of the same length. Thorax cupola-shaped, with large, regular, circular pores, and numerous pyramidal tubercles. Abdomen with twelve (sometimes eleven or thirteen) slender, divergent ribs, which are connected at equal distances by four to six horizontal rings, and so produce twelve longitudinal rows of large, regular, square meshes.

Dimensions.—Length of the three joints, a 0.02, b 0.12, c 0.1; breadth, a 0.03, b 0.14, c 0.15.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

10. Cycladophora dodecapleura, n. sp.

Shell cupola-shaped, with two deep strictures. Length of the three joints = 2 : 5 : 6, breadth = 2 : 7 : 10. Cephalis hemispherical, with a conical horn of twice the length. Thorax subspherical, truncate at both poles, thorny, with regular, circular pores. Abdomen in the upper half with a coronal of twelve large ovate holes, separated by twelve divergent, slender ribs, in the lower half with curved, convergent prolongations of the twelve ribs, and numerous small, irregular, roundish pores.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.06; breadth, a 0.02, b 0.07, c 0.1.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

11. Cycladophora campanula, n. sp.

Shell campanulate, with two slight strictures. Length of the three joints = 2 : 4 : 5, breadth = 2 : 6 : 10. Cephalis ovate, with a conical horn of the same length. Thorax campanulate, rough, with regular, circular pores. Abdomen dilated, with fifteen to twenty slender, divergent, little curved ribs, which are connected by two or three horizontal rings, and from two or three transverse rows of large, roundish, square pores.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.1; breadth, a 0.04, b 0.12, c 0.2.

Habitat.—North Atlantic, Bermuda, surface; also fossil in Barbados.

12. Cycladophora spatiosa, Ehrenberg.

Cycladophora spatiosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. figs. 5, 6.

Shell campanulate, with two slight strictures. Length of the three joints = 2 : 6 : 9, breadth = 3 : 8 : 14. Cephalis subspherical, with a conical horn of the same length. Thorax campanulate, smooth, with regular, circular pores. Abdomen truncate, conical, with sixteen to twenty-four divergent ribs, which are straight or slightly curved, and connected by from four to six transverse, circular rings. The large regular meshes, so produced, form sixteen to twenty-four longitudinal series, and are rounded in the upper, square in the lower transverse rows.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.09; breadth, a 0.03, b 0.08, c 0.14.

Habitat.—Fossil in Barbados.

13. Cycladophora favosa, n. sp. (Pl. 62, figs. 5, 6).

Shell dome-shaped, without collar stricture, but with a deep lumbar stricture. Cephalis flat, cap-shaped, without horn, or with a rudimentary conical horn, with small circular pores. Length of the three joints = 1 : 4 : 3, breadth = 2 : 5 : 4. Thorax subspherical, rough, with regular, circular, hexagonally-framed pores. Abdomen truncate, conical, with eighteen to twenty-four prominent ribs; between every two ribs only two or three ovate pores occur. Mouth circular, with eighteen to twenty-four teeth. The shape of the abdomen is rather variable (figs. 5, 6).

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.06; breadth, a 0.04, b 0.09, c 0.07.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Subgenus 5. Cyclamptidium, Haeckel.

Definition.—Abdomen nearly cylindrical or prismatic, with numerous (ten to twenty or more) straight, vertical, parallel ribs. Mouth wide open, truncate.

14. Cycladophora fenestrata, n. sp. (Pl. 68, fig. 2).

Shell rough, with two slight strictures. Length of the three joints = 1 : 5 : 5, breadth = 1 : 6 : 5. Cephalis conical, with a conical, dimpled horn of twice the length. Thorax nearly spherical, with regular, circular pores, and small conical spines. Abdomen cylindrical, with eighteen stout, parallel, vertical ribs, which are connected by six to eight horizontal, circular rings; therefore regular transverse and longitudinal rows of square or circular pores occur. Mouth truncate, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.1; breadth, a 0.03, b 0.12, c 0.1.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

15. Cycladophora stiligera, Ehrenberg.

Cycladophora stiligera, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. fig. 3.

Shell smooth, with two distinct strictures. Length of the three joints = 2 : 7 : 8, breadth = 2 : 9 : 7. Cephalis subspherical, with a conical horn of twice the length. Thorax subspherical, smooth, with regular, circular pores. Abdomen cylindrical, with twelve parallel, vertical ribs, which are connected by three to four broad, horizontal rings; therefore subregular, transverse, and longitudinal rows of roundish pores are present. Mouth truncate, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.08; breadth, a 0.02, b 0.09, c 0.07.

Habitat.—Fossil in Barbados.

Genus 605. Calocyclas,^[110] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with a simple corona of terminal feet around the truncate mouth. Abdomen not dilated, cylindrical or ovate. No ribs in the shell-wall.

The genus Calocyclas, and the three following closely allied genera, differ from the four preceding genera of Theophormida in the absence of radial or longitudinal ribs in the wall of the thorax and abdomen. These are completely reduced, and their terminal prolongations only remain, forming a simple or double corona around the mouth of the abdomen. They correspond therefore to Carpocanium and Anthocyrtis among the Dicyrtida. In Calocyclas the corona is simple. The mouth is not dilated, but often constricted, and the abdomen is cylindrical or ovate, not conical. The teeth of the corona are usually vertical or convergent.

Subgenus 1. Calocycletta, Haeckel.

Definition.—Thorax and abdomen smooth, without spines or thorns.

1. Calocyclas veneris, n. sp. (Pl. 74, fig. 5).

Shell smooth, with two distinct strictures. Length of the three joints = 1 : 2 : 2, breadth = 1 : 4 : 3. Cephalis ovate, with a large, triangular, prismatic horn of three times the length. Thorax hemispherical; abdomen cylindrical; both with regular, circular pores of equal size. Mouth truncate, with a corona of nine to twelve vertical, lamellar feet, which are as long as the abdomen, rectangular, twice as broad as their distance apart, and truncate at the end.

Dimensions.—Length of the three joints, a 0.03 to 0.04, b 0.06 to 0.08, c 0.04 to 0.06; breadth, a 0.03 to 0.04, b 0.09 to 0.11, c 0.08 to 0.1.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, many stations; surface, and in various depths.

2. Calocyclas virginis, n. sp. (Pl. 74, fig. 4).

Shell smooth, with distinct collar, but indistinct lumbar stricture. Length of the three joints = 1 : 2 : 1, breadth = 1 : 4 : 3. Cephalis ovate, with a slender, conical horn, little shorter than the shell. Thorax subspherical. Abdomen nearly cylindrical, little contracted towards the peristome. Pores regular, circular, twice as broad in the thorax as in the abdomen, where they are separated by slight longitudinal ribs. Corona of the peristome composed of sixteen to twenty-four vertical, lamellar feet, which are longer than the abdomen, rectangular, and truncate at the end.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.05; breadth, a 0.03, b 0.11, c 0.09.

Habitat.—Central Pacific, Station 225, depth 4475 fathoms.

3. Calocyclas minervæ, n. sp.

Shell smooth, with two deep strictures, similar to Cycladophora stiligera. Length of the three joints = 1 : 4 : 3, breadth = 1 : 4 : 3. Cephalis subspherical, with a large, conical horn of three times the length. Thorax subspherical, with small, regular, circular pores. Abdomen cylindrical, with truncate mouth and few irregular pores of different sizes, commonly arranged in three or four subregular, transverse rows, with large intervening distances. Peristome with a corona of twelve to twenty vertical, lamellar feet, which are about as long as the abdomen, and truncate at the end (in Ehrenberg's figure these are broken off).

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.06; breadth, a 0.02, b 0.09, c 0.07.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

4. Calocyclas amicæ, n. sp. (Pl. 74, fig. 2).

Shell smooth, with two slight strictures. Length of the three joints = 2 : 4 : 5, breadth = 2 : 5 : 5. Cephalis subspherical, with a pyramidal horn of the same length. Thorax campanulate-conical; abdomen nearly cylindrical; both with small, subregular, circular pores. Peristome with a corona of twelve to fifteen small, triangular feet, only as large as the thickness of the shell-wall, and separated by distances of twice the size.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.1; breadth, a 0.04, b 0.1, c 0.1.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

5. Calocyclas sacerdotis, n. sp.

Shell smooth, with two deep strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 3 : 3. Cephalis ovate, with a pyramidal horn of three times the length. Thorax campanulate, conical; abdomen twice the length, cylindrical; both with small, regular, circular pores. Peristome somewhat constricted, with a corona of nine to twelve conical feet, which are as long as the cephalis, and with the ends curved inwards, protecting the mouth.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.12; breadth, a 0.03, b 0.09, c 0.09.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

6. Calocyclas vestalis, n. sp. (Pl. 74, fig. 3).

Shell smooth, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 3. Cephalis subspherical, with a pyramidal horn of twice the length. Thorax campanulate; abdomen nearly cylindrical; both with regular, hexagonal pores, three times as broad as the bars. Peristome constricted, half as broad as the abdomen, with a corona of nine conical, vertical feet as long as the cephalis.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.1; breadth, a 0.035, b 0.1, c 0.1.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subgenus 2. Calocyclissa, Haeckel.

Definition.—Thorax spiny or thorny; abdomen smooth.

7. Calocyclas turris, Ehrenberg.

Calocyclas turris, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xviii. fig. 7.

Shell with two sharp strictures. Length of the three joints = 1 : 4 : 4, breadth = 1 : 5 : 4. Cephalis hemispherical, with a stout conical horn of the same length. Thorax subspherical, thorny with small, regular, circular, quincuncial pores. Abdomen cylindrical, smooth, nearly hyaline, with very scarce, irregular, widely scattered pores. Peristome with a corona of fifteen to twenty broad, lamellar, vertical, truncate feet, about as long as the abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.08; breadth, a 0.03, b 0.1, c 0.08.

Habitat.—Fossil in Barbados.

8. Calocyclas hyalogaster, n. sp.

Shell with two sharp strictures. Length of the three joints = 1 : 4 : 6, breadth = 1 : 4 : 3. Cephalis subspherical, with a conical horn of twice the length. Thorax subspherical, thorny, with regular, circular pores. Abdomen cylindrical, smooth, quite hyaline, without any pores. Peristome with a corona of twelve broad, lamellar, vertical, truncate feet, half as long as the abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.12; breadth, a 0.02, b 0.08, c 0.06.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

9. Calocyclas erinaceus, Haeckel.

Cycladophora erinaceus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. fig. 2.

Shell with two sharp strictures. Length of the three joints = 2 : 9 : 5, breadth = 3 : 9 : 5. Cephalis subspherical, rough, with a short and broad conical horn of half the length. Thorax ovate, densely covered with conical spines as long as the horn, and with regular, circular, quincuncial pores. Abdomen cylindrical, smooth, with irregular roundish pores of different sizes. Peristome with twelve to fifteen vertical, broad, lamellar, truncate feet half as long as the abdomen (in Ehrenberg's figure these are broken off).

Dimensions.—Length of the three joints, a 0.04, b 0.18, c 0.1; breadth, a 0.06, b 0.18, c 0.1.

Habitat.—Fossil in Barbados.

10. Calocyclas gigas, Haeckel.

Cycladophora gigas, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. fig. 1.

Shell with two sharp strictures. Length of the three joints = 2 : 5 : 3, breadth = 2 : 6 : 4. Cephalis subspherical, rough, with a short and broad conical horn of half the length. Thorax subspherical, campanulate, thorny, with subregular, circular pores (smaller and more numerous than in the preceding). Abdomen cylindrical, smooth, with a small number of sparsely disposed, roundish, irregularly scattered pores. Peristome with twenty to thirty short, lamellar, truncate, vertical feet about half as long as the cephalis.

Dimensions.—Length of the three joints, a 0.06, b 0.15, c 0.09; breadth, a 0.06, b 0.18, c 0.12.

Habitat.—Fossil in Barbados.

Subgenus 3. Calocycloma, Haeckel.

Definition.—Thorax smooth; abdomen spiny or thorny.

11. Calocyclas casta, n. sp. (Pl. 73, fig. 10).

Shell ovate, with two sharp strictures. Length of the three joints = 1 : 2 : 8, breadth = 2 : 4 : 8. Cephalis hemispherical, with a strong pyramidal horn of twice the length. Thorax campanulate, smooth, with small, regular, circular pores. Abdomen inflated, subspherical, covered with large conical spines, and large intervening circular pores (four times as broad as the thoracic pores). Mouth constricted, only one-third as broad as the abdomen, with a peristome of nine to twelve conical vertical feet as long as the abdominal spines. (In the specimen figured they were broken off.)

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.15; breadth, a 0.04, b 0.08, c 0.15.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

12. Calocyclas pudica, n. sp.

Shell ovate, with two distinct strictures. Length of the three joints = 1 : 3 : 8, breadth = 1 : 4 : 6. Cephalis subspherical, with a conical horn of three times the length. Thorax and abdomen nearly of the same shape as in the preceding species, but more slender and the regular, circular pores of the abdomen only twice as broad as the thoracic pores. Conical spines of the abdomen only half as large, but more numerous. Peristome constricted, half as broad as the abdomen, with sixteen to twenty short, conical, vertical feet as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.16; breadth, a 0.025, b 0.08, c 0.12.

Habitat.—Central Pacific Station 266, depth 2750 fathoms.

Subgenus 4. Calocyclura, Haeckel.

Definition.—Thorax and abdomen spiny or thorny.

13. Calocyclas parthenia, n. sp. (Pl. 74, fig. 1).

Shell nearly ovate, with thorny surface, and two slight strictures. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 5. Cephalis hemispherical, armed with numerous short, conical thorns, and with a pyramidal, very large, vertical horn as long as the thorax, and on the basal half as broad as the cephalis. Thorax hemispherical, separated by a slight stricture from the broader, barrel-shaped abdomen, which is a little constricted at the mouth. Teeth of the coronal about twenty, triangular, short, little divergent. Pores circular, somewhat irregular in size, three to four times as broad as the bars, in all three joints nearly of the same shape.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.11; breadth, a 0.05, b 0.1, c 0.12.

Habitat.—Indian Ocean, Cocos Islands, surface (Rabbe).

14. Calocyclas aspasia, n. sp.

Shell ovate, conical, with two deep strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, with a conical horn of twice the length. Thorax and abdomen nearly of the same shape as in the preceding species, but covered with longer conical spines, less numerous, and twice as long as the diameter of the subregular, circular pores. Mouth more constricted, and armed with a coronal of twelve to sixteen broad, lamellar feet, as long as the cephalis, and similar to those of Calocyclas puella (Pl. 74, fig. 5).

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.08; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

15. Calocyclas monumentum, n. sp. (Pl. 73, fig. 9).

Shell nearly conical, with two very deep strictures, everywhere covered with long, bristle-shaped, divergent spines, about as long as the thorax. Length of the three joints = 1 : 2 : 2, breadth = 1 : 4 : 6. Cephalis nearly spherical, with a very large, three-sided pyramidal horn of twice the length. Thorax and abdomen of similar form, campanulate, with a lower cylindrical, and an upper truncate, conical part. Pores irregular, roundish, in the smaller thorax of slightly different sizes, in the larger abdomen three to four transverse rows of larger pores (six to eight in each row) are separated by numerous much smaller pores. Peristome wide open, with a coronal of twelve large, triangular, vertical feet, nearly as long as the abdomen; in the base of each foot a large, roundish, triangular pore.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.06; breadth, a 0.04, b 0.12, c 0.18.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 606. Clathrocyclas,^[111] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with a simple corona of terminal feet around the dilated mouth. Abdomen dilated, truncate-conical, or discoidal. No ribs in the shell-wall.

The genus Clathrocyclas differs from the preceding closely allied Calocyclas in the dilated mouth and the flatter form of the abdomen, which is usually truncate, conical, or nearly discoidal. The conical thorax is often separated from the flat abdomen by an elegant ribbon of small quadrangular pores. The feet or teeth of the terminal corona are divergent, or even horizontally expanded, whilst in Calocyclas they are usually vertical or somewhat convergent.

Subgenus 1. Clathrocyclia, Haeckel.

Definition.—Shell highly conical, often ovate or slenderly campanulate. Cephalis commonly with a single horn.

1. Clathrocyclas principessa, n. sp. (Pl. 74, fig. 7).

Shell ovate, with two distinct strictures. Length of the three joints = 1 : 2 : 1, breadth = 1 : 2 : 2. Cephalis hemispherical, large, with a pyramidal, occipital horn of the same length. Thorax subspherical, with irregular, circular pores, about as broad as the bars. Abdomen short, widely open with a single transverse row of circular pores, and a coronal of twelve triangular, divergent feet, as long as the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.03; breadth, a 0.04, b 0.08, c 0.09.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Clathrocyclas basilea, (Pl. 74, fig. 6).

Shell campanulate, with two deep strictures. Length of the three joints = 2 : 5 : 3, breadth = 3 : 7 : 9. Cephalis hemispherical, with an ovate, oblique horn of the same length. Thorax hemispherical, with subregular, circular pores of the same breadth as the bars. Abdomen short, with two transverse rows of the same pores, and with a coronal of sixteen to twenty ovate, divergent feet, as long as the horn.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.03; breadth, a 0.035, b 0.07, c 0.09.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

3. Clathrocyclas fimbriata, Haeckel.

? Halicalyptra fimbriata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ii. fig. 11.

Shell campanulate, with two deep strictures. Length of the three joints = 1 : 3 : 1, breadth = 1 : 3 : 5. Cephalis hemispherical, with a conical horn of twice the length. Thorax hemispherical, in the upper half hyaline, without pores, in the lower half with four to six transverse rows of subregular, circular pores. Abdomen short, suddenly dilated, with one or two transverse rows of larger ovate pores (six to eight in one row), and with a coronal of twelve to fifteen divergent, slender, curved feet, as long as the cephalis. (In the figure of Ehrenberg, seen half from below, the cephalis is not represented.)

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.02; breadth, a 0.02, b 0.06, c 0.1.

Habitat.—Fossil in Barbados.

4. Clathrocyclas collaris, n. sp. (Pl. 74, fig. 8).

Shell subconical, with two indistinct strictures. Length of the three joints = 1 : 1 : 2, breadth = 1 : 2 : 3. Cephalis hemispherical, with a triangular prismatic horn three times the length. Thorax truncate, conical, with a single transverse row of circular pores, each of which is placed in the lower end of an oblong, lanceolate, longitudinal furrow; collar composed of fifteen to twenty such furrows. Abdomen inflated, with four to six transverse rows of circular pores, and with a coronal of nine triangular, divergent feet, longer than the collar.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.06; breadth, a 0.03, b 0.06, c 0.09.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

5. Clathrocyclas puella, Haeckel.

Podocyrtis puella sinensis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiv. fig. 3.

Shell subconical, with two indistinct strictures. Length of the three joints = 1 : 1 : 2, breadth = 1 : 2 : 3. Cephalis hemispherical, with a pyramidal horn of twice the length. Pores subregular, circular, quincuncial, in the dilated abdomen (with four to five transverse rows), twice to three times as large as in the short thorax (with two to three rows). Coronal of the wide peristome with fifteen to twenty short, triangular, divergent feet, about as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.04; breadth, a 0.02, b 0.04, c 0.06.

Habitat.—Fossil in Barbados.

6. Clathrocyclas domina, Haeckel.

Podocyrtis domina sinensis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xiv. fig. 4.

Shell subconical, with two slight strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 4. Cephalis ovate, with a conical horn of the same length (and sometimes with some little accessory thorns at its base). Pores subregular, circular, quincuncial, in the dilated abdomen (with six to eight transverse rows), twice to four times as large as in the hemispherical thorax (with four to six rows). Coronal of the wide peristome with nine to twelve short, triangular, divergent feet, half as long as the cephalis (in Ehrenberg's figure incomplete).

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.06, c 0.08.

Habitat.—Central Pacific, Stations 263 to 268, depth 2650 to 3000 fathoms; also fossil in Barbados.

Subgenus 2. Clathrocycloma, Haeckel.

Definition.—Shell flatly conical, often widely campanulate, or nearly discoidal. Cephalis commonly with two or more horns.

7. Clathrocyclas alcmenæ, n. sp. (Pl. 59, fig. 6).

Shell conical, with two indistinct strictures. Length of the three joints = 2 : 10 : 1, breadth = 2 : 12 : 14. Cephalis hemispherical, with two divergent, pyramidal horns; frontal horn as long as the cephalis, occipital horn of twice the length. Thorax conical, with large hexagonal meshes, increasing gradually in size towards the short abdomen, which is represented only by a single circular girdle of small, square, abdominal pores. Coronal of the peristome with twenty to thirty triangular, divergent, nearly horizontal feet, as long as the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.01. breadth, a 0.02, b 0.12, c 0.14.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

8. Clathrocyclas europæ, n. sp. (Pl. 59, figs. 11, 12).

Shell conical, almost of the same form as the preceding nearly allied species, differing from it in the concave (not straight) outline of the flatter conical thorax, in the more rounded form of its pores, and in the subspherical form of the cephalis, bearing only a single conical horn of the same length. Length of the three joints = 2 : 8 : 1, breadth = 2 : 12 : 14. In fig. 11 the cephalis is broken off, so that the four cortinar pores are visible (two smaller jugular and two larger cardinal pores, separated by two coracal beams).

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.01. breadth, a 0.02, b 0.12, c 0.14.

Habitat.—Mediterranean, Corfu (Haeckel), surface.

9. Clathrocyclas semeles, n. sp. (Pl. 58, fig. 5).

Shell conical-campanulate, with two distinct strictures. Length of the three joints = 2 : 8 : 1, breadth = 2 : 8 : 10. Cephalis hemispherical, with three divergent, conical horns (the caudal horn, directed downwards, much longer than the occipital and frontal horns). Pores of the thorax large, roundish. Abdomen (as in the two preceding species) with only a single circle of forty to fifty small square pores. Coronal with about the same number of short, triangular, almost horizontally divergent feet.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.01. breadth, a 0.02, b 0.08, c 0.1.

Habitat.—Central Pacific, Station 271, surface.

10. Clathrocyclas danaës, n. sp. (Pl. 59, figs. 13, 14).

Shell flatly conical, with straight outline (as in Clathrocyclas alcmenæ, Pl. 59, fig. 6). Length of the three joints = 1 : 5 : 1, breadth = 2 : 8 : 1. Cephalis hemispherical, with a single, short, conical, oblique horn (broken off in the specimen figured). Pores of the thorax polygonal, increasing gradually in size towards the girdle (in three to four circles.) Abdomen nearly horizontally expanded with two rows of pores, the inner with very small and numerous square pores, the outer with twenty to thirty much larger quadrangular pores. Coronal of the peristome with the same number of short, divergent feet, alternating with the larger pores.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.02; breadth, a 0.04, b 0.15, c 0.2.

Habitat.—North Atlantic, Canary Islands (Lanzerote), Station 354, surface.

11. Clathrocyclas jonis, n. sp. (Pl. 59, fig. 9).

Shell campanulate, with two slight strictures. Length of the three joints = 1 : 5 : 2, breadth = 1 : 6 : 8. Cephalis small, hemispherical, with two divergent, conical horns of nearly equal length. Pores of the thorax polygonal, increasing in size towards the girdle; in the upper half filled up by an extremely fine and delicate cobweb-like network. Abdomen with two rows of pores, of the same shape as in the preceding species, also with equal coronal.

Dimensions.—Length of the three joints, a 0.03, b 0.1, c 0.03; breadth, a 0.02, b 0.12, c 0.16.

Habitat.—Central Pacific, Station 274, surface.

12. Clathrocyclas latonæ, n. sp. (Pl. 59, fig. 7).

Shell campanulate, very similar to the preceding species, but flatter and different in the larger cephalis, bearing only a single oblique horn. All the polygonal pores of the thorax are filled out by delicate cobweb-like network. Length of the three joints = 1 : 3 : 1, breadth = 1 : 4 : 6. Abdomen with three circular rows of quadrangular pores; first very small and numerous, second of median size, third very large. Coronal with thirty to forty short triangular feet.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.03; breadth, a 0.03, b 0.12, c 0.18.

Habitat.—Tropical Atlantic, Station 325, surface.

13. Clathrocyclas coscinodiscus, n. sp. (Pl. 58, figs. 3, 4).

Shell flatly campanulate, with two distinct strictures. Length of the three joints = 1 : 5 : 2, breadth = 1 : 8 : 10. Cephalis hemispherical, with two divergent, pyramidal horns of the same length. Thorax with concave outline, with numerous hexagonal pores, gradually increasing in size towards the girdle, except the outermost row (inside the girdle), which is composed of very small, square pores. Abdomen (outside the girdle) with three rows of pores; first with small, second with median, third with large pores. Coronal with eighty to one hundred short, divergent feet.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.03; breadth, a 0.025, b 0.16, c 0.2.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

14. Clathrocyclas cassiopeiæ, n. sp. (Pl. 59, fig. 5).

Shell flatly campanulate, with two slight strictures. Length of the three joints = 2 : 4 : 3, breadth = 2 : 6 : 8. Cephalis ovate, thorny, with a pyramidal horn of the same length, and several smaller accessory horns. Thorax smooth, with irregular, polygonal pores of nearly equal size. Abdomen spiny, with three to four irregular rows of similar pores. Coronal with sixty to ninety or more irregularly and obliquely divergent feet, little larger than the abdominal spines.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.06; breadth, a 0.03, b 0.12, c 0.16.

Habitat.—Indian Ocean, Madagascar, Rabbe, surface.

Genus 607. Lamprocyclas,^[112] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with a double corona of solid terminal feet around the mouth. No ribs in the shell-wall.

The genus Lamprocyclas differs from Calocyclas, its ancestral form, in the duplication of the terminal corona. Usually the feet or teeth of the lower corona are convergent and curved inwards, whilst the teeth of the upper corona are divergent and curved outwards. Sometimes above the latter a third corona begins to be developed. The whole shell is more or less conical, very thick-walled, with a large and stout apical horn.

Subgenus 1. Lamprocyclia, Haeckel.

Definition.—Feet of the peristome simple, not branched.

1. Lamprocyclas nuptialis, n. sp. (Pl. 74, fig. 15).

Shell campanulate, nearly smooth, with two slight strictures. Length of the three joints = 1 : 2 : 2, breadth = 1 : 3 : 4. Cephalis ovate, with a very large, three-sided prismatic horn, nearly as long as the shell. Thorax and abdomen gradually dilated, with regular, circular, double-edged pores. Outer coronal of the peristome with twelve to fifteen divergent feet, inner with as many subvertical, triangular, little curved feet, about as long as the cephalis.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.06; breadth, a 0.03, b 0.09, c 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Lamprocyclas maritalis, n. sp. (Pl. 74, figs. 13, 14).

Shell campanulate, very similar to the preceding species in form and fenestration, but not so slender and with different peristome. Length of the three joints = 4 : 5 : 6, breadth = 4 : 10 : 13. Cephalis subspherical, with a very stout, pyramidal horn of twice the length, the edges of which are spirally convoluted. Outer coronal of the peristome with twelve to fifteen short, divergent feet, inner with as many convergent, longer feet.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.06; breadth, a 0.04, b 0.1, c 0.13.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Lamprocyclas deflorata, n. sp. (Pl. 74, fig. 10).

Shell ovate, smooth, with deep collar, but indistinct lumbar stricture; very similar to the two preceding species, but with different horn and peristome. Length of the three joints = 3 : 5 : 8, breadth = 3 : 10 : 13. Cephalis subspherical, with a pyramidal horn of twice the length, the three faces of which are deeply concave. Thoracic pores half as large as the abdominal, both subregular, double-edged. Outer coronal of the wide peristome with nine short, triangular, subvertical feet, inner with nine larger, horizontal feet, lying in the plane of the wide mouth.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.08; breadth, a 0.03, b 0.1, c 0.13.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

4. Lamprocyclas saltatricis, n. sp. (Pl. 74, fig. 16).

Shell conical, rough, with two slight strictures. Length of the three joints = 2 : 2 : 3, breadth = 1 : 4 : 6. Cephalis ovate, with a large, prismatic horn, half as long as the shell. Pores subregular, circular, not double-edged, three times as broad in the inflated abdomen as in the hemispherical thorax. Outer coronal of the wide peristome with twelve to fifteen divergent feet, inner with fifteen to twenty conical feet, which are curved inwards nearly horizontally.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.07; breadth, a 0.025, b 0.1, c 0.15.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

5. Lamprocyclas reginæ, n. sp. (Pl. 74, figs. 11, 12).

Shell campanulate, with two slight strictures. Length of the three joints = 2 : 3 : 3, breadth = 2 : 5 : 6. Cephalis subcylindrical, with about fifteen longitudinal rows of circular pores, separated by prominent, parallel crests, and with a very large sword-like horn, nearly as long as the shell. Thorax hemispherical, smooth, with elegant, circular, hexagonally-framed pores. Abdomen dilated, with similar but larger pores, armed with hook-shaped spines. The two inferior rows of these hooks form the double coronal of the peristome; the feet of the outer are curved downwards, of the inner inwards.

Dimensions.—Length of the three joints, a 0.04, b 0.06, c 0.06; breadth, a 0.04, b 0.1, c 0.12.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

6. Lamprocyclas ægles, Haeckel.

Podocyrtis ægles, Ehrenberg, 1854, Mikrogeol., Taf. xxxv. B. B iv. fig. 18.

Shell campanulate, conical, thorny, with two deep strictures. Length of the three joints = 3 : 5 : 5, breadth = 3 : 8 : 11. Cephalis ovate, with a stout, three-sided prismatic horn of twice the length. Pores subregular, circular, twice as broad in the inflated abdomen as in the campanulate thorax, and four times as broad as in the cephalis. Outer coronal of the wide peristome with fifteen to twenty conical, divergent feet, inner coronal with a smaller number of vertical, parallel, divergent feet.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.05; breadth, a 0.03, b 0.08, c 0.11.

Habitat.—North Atlantic, depth 1400 fathoms (Berrymann).

Subgenus 2. Lamprocycloma, Haeckel.

Definition.—Feet of the peristome forked or branched.

7. Lamprocyclas bajaderæ, n. sp.

Shell campanulate, very similar to the preceding species, but with stronger spines on the abdomen and with different peristome. Length of the three joints = 2 : 2 : 3, breadth = 2 : 6 : 8. Cephalis equal to that of Lamprocyclas maritalis (Pl. 74, figs. 13, 14). Outer coronal of the peristome with fifteen to twenty divergent, pyramidal feet, half as long as the horn; inner coronal with as many longer, vertical feet, which are irregularly forked or branched.

Dimensions.—Length of the three joints, a 0.04, b 0.04, c 0.06; breadth, a 0.04, b 0.12, c 0.16.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

Genus 608. Diplocyclas,^[113] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theophormida (vel Tricyrtida multiradiata aperta) with a double corona of radial solid feet, an upper around the lumbar stricture, a lower around the mouth. No ribs in the shell-wall.

The genus Diplocyclas differs from all the other Theophormida in the possession of a double coronal of radial teeth, an upper between thorax and abdomen, and a lower around the terminal mouth of the latter; it may be regarded as an Anthocyrtis, which has formed an abdomen, and repeated the terminal armature. The cephalis bears a single or double apical horn.

1. Diplocyclas bicorona, n. sp. (Pl. 59, fig. 8).

Shell slender, campanulate. Length of the three joints = 1 : 3 : 2, breadth = 1 : 4 : 4. Cephalis subspherical, with two divergent horns; the occipital of the same length and forked, the frontal shorter and simple. Thorax campanulate, with six to eight transverse rows of double-edged roundish pores of increasing size. Abdomen cylindrical, with three transverse rows of large polygonal pores, and a terminal row of very small square pores. Lumbar and terminal coronals of similar shape, each with twenty to thirty short divergent feet.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.025, b 0.08, c 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Diplocyclas bicincta, n. sp.

Shell campanulate, in general of the same form as, and similar fenestration to, the preceding species but not so slender, and with different proportions. Length of the three joints = 1 : 4 : 2, breadth = 2 : 5 : 5. Cephalis hemispherical, with a single, conical, simple horn. Pores of the thorax hexagonal, of increasing size (in eight to ten transverse rows). Abdomen with smaller square pores (in four to six rows). The two coronals of the same shape as in Pl. 59, fig. 8.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.04; breadth, a 0.04, b 0.1, c 0.1.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

3. Diplocyclas bizonalis, n. sp.

Shell subconical, with indistinct collar and distinct lumbar stricture. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis hemispherical, with two divergent conical horns of equal size. Thorax conical, with small, irregular, double-edged pores, and a terminal corona of about nine very large pores. Abdomen truncate, conical, with three to four transverse rows of roundish, quadrangular, very large pores. Lumbar and terminal coronals of similar shape, each with twelve to fifteen triangular divergent feet.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.06; breadth, a 0.02, b 0.06, c 0.08.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

Subfamily 2. Theophænida, Haeckel, 1881, Prodromus, p. 437.

Definition.—Phormocyrtida with the basal mouth of the shell fenestrated (vel Tricyrtida multiradiata clausa).

Genus 609. Hexalatractus,^[114] n. gen.

Definition.—Theophænida (vel Tricyrtida multiradiata clausa) with six lateral wings on the abdomen.

The genus Hexalatractus, and the following genus Theophæna, represent together the small subfamily Theophænida, or those Tricyrtida in which the terminal mouth of the shell is closed by lattice-work, and six or nine lateral apophyses indicate a multiradiate structure. The shell is more or less ovate or spindle-shaped, tapering towards both poles, and resembles greatly the triradiate Rhopalocanium. It may be derived from the latter by interpolation of three secondary or interradial wings between the three primary or perradial apophyses.

1. Hexalatractus sexalatus, n. sp.

Shell ovate, smooth, with two distinct strictures, length of the three joints = 3 : 6 : 9, breadth = 4 : 9 : 8. Cephalis subspherical, with a pyramidal horn of twice the length. Thorax campanulate; abdomen inversely conical; both with subregular, circular pores. Six divergent wings arise, beginning from the collar stricture, from the upper half of the shell, with broad triangular base; they are little curved downwards, with the convexity outside, and gradually tapering towards the distal end; the latter lies in the same horizontal plane as the basal apex of the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.04, b 0.09, c 0.08.

Habitat.—Central Pacific, Stations 263, depth 2650 fathoms.

2. Hexalatractus fusiformis, n. sp. (Pl. 68, fig. 13).

Shell rough, nearly spindle-shaped, with sharp collar and slight lumbar stricture. Length of the three joints = 2 : 5 : 12, breadth = 3 : 8 : 7. Cephalis hemispherical, with a conical horn of the same length. Thorax hemispherical with regular, circular, hexagonally-framed pores. Abdomen inversely conical, with irregular, roundish pores. From the upper half of the abdomen arise, with broad triangular base, six divergent wings, which are nearly straight, and slightly fenestrated at the base; their conical distal ends do not reach the horizontal plane, in which the basal apex of the abdomen lies.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.12; breadth, a 0.03, b 0.08, c 0.07.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 610. Theophæna,^[115] Haeckel, 1881, Prodromus, p. 437.

Definition.—Theophænida (vel Tricyrtida multiradiata clausa) with nine lateral wings on the abdomen.

The genus Theophæna differs from the preceding six-radiate Hexalatractus in the possession of nine lateral wings, and may be derived from the triradiate Rhopalocanium by interpolation of six secondary wings between the three primary apophyses.

1. Theophæna corona, n. sp. (Pl. 70, fig. 12).

Shell rough, nearly spindle-shaped, with two sharp strictures. Length of the three joints = 4 : 9 : 16, breadth = 5 : 12 : 10. Cephalis hemispherical, very thick-walled, with a conical horn of the same length; both covered with numerous small dimples and spinules. Thorax campanulate; abdomen inversely conical; both with regular, circular pores. Thorax with nine thin curved ribs, which in the upper half of the abdomen arise as nine large feet, which are strongly compressed and curved (with the convexity outwards); their distal ends form nine ovate spinulate cones, and lie in the same horizontal plane as the basal apex of the abdomen.

Dimensions.—Length of the three joints, a 0.04, b 0.09, c 0.16; breadth, a 0.05, b 0.12, c 0.1.

Habitat.—Indian Ocean, Madagascar (Rabbe), surface.

2. Theophæna nonaria, n. sp.

Shell thorny, ovate, with two slight strictures. Length of the three joints = 1 : 4 : 5, breadth = 1 : 5 : 4. Cephalis subspherical, with a conical horn of half the length. Thorax subspherical, with regular, circular pores and conical spines. Abdomen ovate, smooth, with irregular, roundish pores. In the upper half of the thorax descend nine straight, little divergent ribs, which in the lower half become free, and represent nine slender, conical wings; their distal ends do not reach the horizontal plane in which the basal end of the abdomen lies.

Dimensions.—Length of the three joints, a 0.03, b 0.12, c 0.15; breadth, a 0.03, b 0.14, c 0.12.

Habitat.—South of Australia, Station 160, surface.

Family LXVII. Theocyrtida, n. fam.

Theocorida et Theocapsida, Haeckel, 1881, Prodromus, pp. 434, 436.

Definition.—Tricyrtida eradiata. Cyrtoidea with a three-jointed shell, divided by two transverse constrictions into cephalis, thorax, and abdomen, without radial apophyses.

The family Theocyrtida, composed of the Theocorida and Theocapsida of my Prodromus, comprises those Cyrtoidea in which the lattice-shell is three-jointed, and bears no external radial apophyses. The two subfamilies differ in the shape of the terminal mouth, which in the Theocorida is a simple wide opening, in the Theocapsida closed by a lattice-plate. The phylogenetic origin of the Theocyrtida may be found either in the Podocyrtida or in the Sethocyrtida; they may have been derived from the former by reduction and loss of the three primary apophyses, or from the latter by development of an abdomen.

The number of species in this group is very large, and many belong to the most common and widely distributed Cyrtoidea. A great number of living and fossil species have already been described by Ehrenberg, the majority being disposed in his genera Lithocampe and Eucyrtidium.

The number of genera, however, is comparatively small, and their distinction difficult, since the form of the shell presents no striking differences.

It exhibits all possible passages, from a flatly expanded or nearly discoidal form with a wide open mouth, to a conical or cylindrical, and by constriction of the terminal mouth to an ovate or spindle-shaped form. By complete closure of the mouth the Theocapsida arise. In some genera remarkable traces of the original triradial structure are preserved. The most interesting of these forms is Axocorys, with an internal axial columella, which bears a number of verticils, each with three radial branches.

Synopsis of the Genera of Theocyrtida.

I. Subfamily Theocorida. Terminal mouth of the abdomen a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Abdomen gradually dilated towards the wide open mouth.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Abdomen flatly expanded, discoidal.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	With horn,	611. Theocalyptra.
						No horn,	612. Cecryphalium.
				Abdomen conical.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	One horn,	613. Theoconus.
						Two or more horns,	614. Lophoconus.
		Abdomen cylindrical, of nearly equal breadth throughout its whole length. Mouth truncate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	A single apical horn on the cephalis.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Thorax and abdomen of equal breadth,	615. Theocyrtis.
						Thorax much broader than the tubular abdomen,	616. Theosyringium.
				Two horns or a bunch of horns on the cephalis,			617. Lophocyrtis.
				No horn on the cephalis,			618. Tricolocampe.
		Abdomen ovate or inversely conical. Mouth more or less constricted.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	A single apical horn on the cephalis.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell-cavity without an internal columella,	619. Theocorys.
						Shell-cavity with an axial columella,	620. Axocorys.
				Two horns or a bunch of horns on the cephalis,			621. Lophocorys.
				No horn on the cephalis,			622. Theocampe.
II. Subfamily Theocapsida. Terminal mouth closed by a lattice-plate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	No latticed septum between thorax and abdomen.			$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	An apical horn,	623. Theocapsa.
						No horn on the cephalis,	624. Tricolocapsa.
		A complete latticed septum between thorax and abdomen,					625. Phrenocodon.

Subfamily 1. Theocorida, Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocyrtida with the basal mouth of the shell open (vel Tricyrtida eradiata aperta).

Genus 611. Theocalyptra,^[116] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with discoidal or flatly expanded abdomen. Cephalis with a single apical horn, or with two divergent horns.

The genus Theocalyptra, and the following closely allied genus Cecryphalium, differ from all the other Theocorida in the flattened form of the cap-shaped or nearly discoidal shell. The abdomen specially is quite flat, often horizontally expanded, and like the marginal brim of a flat hat. They may be derived from the Dicyrtida Sethocephalus by the development of an abdomen, or from Corocalyptra by loss of the collar wings. The network is usually very delicate, as in the latter. The cephalis of Theocalyptra bears one or two horns.

1. Theocalyptra veneris, n. sp.

Shell flatly campanulate, very delicate and fragile, very similar to Eucecryphalus agnesæ (Pl. 59, fig. 3), but without collar spines. Length of the three joints = 1 : 4 : 2, breadth = 1 : 7 : 9. Cephalis hemispherical, with a single bristle-shaped horn of twice the length. Thorax subconical, separated from the flatter abdomen by a deep stricture, with thin bars, and large, subregular, hexagonal meshes, increasing in size towards the smooth mouth-edge.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.04; breadth, a 0.025, b 0.15, c 0.1.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific, many stations, surface.

2. Theocalyptra orci, Haeckel.

Halicalyptra orci, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. x. figs. 9, 10.

Shell flatly campanulate, very similar to the preceding species in general form and fenestration, but flatter and smaller, with different proportions. Length of the three joints = 7 : 2 : 1, breadth = 1 : 6 : 8. Cephalis hemispherical, very small, with two divergent, bristle-shaped horns of the same length. Abdomen nearly horizontally expanded.

Dimensions.—Length of the three joints, a 0.015, b 0.04, c 0.01; breadth, a 0.02, b 0.12, c 0.16.

Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).

3. Theocalyptra discoides, Haeckel.

Cycladophora discoides, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xviii. fig. 4.

Shell flatly campanulate, similar to the two preceding species, but not so delicate, with thicker bars, and roundish, not hexagonal meshes. Length of the three joints = 1 : 2 : 2, breadth = 3 : 6 : 9. Cephalis large, trilobed, with a short, oblique horn of half the length. Thorax campanulate, conical, separated from the abdomen by a circle of smaller pores and a deep stricture. Abdomen flat, discoidal, with three circles of larger pores.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.04; breadth, a 0.06, b 0.12, c 0.18.

Habitat.—Fossil in Barbados.

4. Theocalyptra cornuta, Haeckel.

Carpocanium cornutum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. ii. fig. 9.

Halicalyptra cornuta, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii. p. 5, pl. i. figs. 13, 14.

Lophophæna cornuta, Haeckel, 1862, Monogr. d. Radiol., p. 299.

Shell campanulate-conical, with two sharp strictures. Length of the three joints = 1 : 3 : 1, breadth = 1 : 4 : 5. Cephalis subspherical, with two stout, pyramidal, divergent horns of twice the length. Thorax campanulate, with eight to ten transverse rows of roundish or nearly square pores, increasing in size towards the abdomen, which is flatly expanded, nearly discoidal, separated by a circle of smaller pores; the last circle of pores (on the margin) is larger.

Dimensions.—Length of the three joints, a 0.025, b 0.09, c 0.03; breadth, a 0.03, b 0.12, c 0.16.

Habitat.—Arctic Ocean, Kamtschatka (Bailey), Greenland (Ehrenberg).

Genus 612. Cecryphalium,^[117] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with discoidal or flatly expanded abdomen. Cephalis without horn.

The genus Cecryphalium has the same flat, conical, or nearly discoidal shell as the preceding Theocalyptra, its ancestral genus, but differs from it in the complete absence of horns on the cephalis.

1. Cecryphalium lamprodiscus, n. sp. (Pl. 58, fig. 2).

Shell flatly conical, with two slight strictures. Length of the three joints = 1 : 3 : 2, breadth = 1 : 7 : 11. Cephalis roundish, very small. Thorax conical, with straight lateral outline; its pores irregular, polygonal, increasing in size towards the girdle. Abdomen little flatter than the thorax, forming its direct prolongation, with five to six circular, concentric rows of pores; the first row formed by sixty to eighty very large, oblongish, quadrangular pores, the second row by very small, the third again by larger pores; the outmost rows by very small and numerous pores.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.04; breadth, a 0.02, b 0.14, c 0.22.

Habitat.—Central Pacific, Station 272, surface.

2. Cecryphalium sestrodiscus, n. sp. (Pl. 58, fig. 1).

Shell very flat, subconical, nearly discoidal, with two distinct strictures. Length of the three joints = 1 : 2 : 1, breadth = 1 : 8 : 10. Cephalis kidney-shaped, very small. Thorax flat, campanulate, with curved lateral outline; its pores irregular, polygonal, increasing in size towards the girdle. Abdomen horizontally expanded, like the brim of a hat, with five to six concentric, circular rows of pores, the pores of the inner rows twice to three times as large as those of the outer rows. (The inner circle of large, oblongish, quadrangular pores, characteristic of the preceding species, is here divided into three concentric rings by two circular hoops.)

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.02; breadth, a 0.02, b 0.15, c 0.2.

Habitat.—Central Pacific, Station 274, surface.

Genus 613. Theoconus,^[118] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with conical abdomen, gradually dilated towards the wide open mouth. Cephalis with a single horn.

The genus Theoconus, and the following closely allied Lophoconus, differ from the other Theocorida in the conical or campanulate form of the shell; the abdomen is a truncated cone, gradually dilated towards the terminal mouth. The latter is usually truncated, widely open, sometimes with a slightly constricted peristome. The cephalis of Theoconus bears a single apical horn.

Subgenus 1. Theocorax, Haeckel.

Definition.—Pores of the thorax and of the abdomen of nearly equal size and similar form.

1. Theoconus zancleus, Haeckel.

Eucyrtidium zancleum, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 41, Taf. vi. figs. 1-3. Eucyrtidium zancleum, Haeckel, 1862, Monogr. d. Radiol., p. 321.

Shell bell-shaped, nearly conical, smooth. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 6. Cephalis nearly spherical, with a stout, straight, pyramidal horn of the same length. Thorax hemispherical. Abdomen gradually increasing in breadth towards the wide truncated mouth. Pores in all three joints nearly of the same shape, circular, regular, four times as broad as the thin bars.

Dimensions.—Length of the three joints, a 0.027, b 0.08, c 0.1; breadth, a 0.03, b 0.12, c 0.18.

Habitat.—Mediterranean (Messina, Naples, Nice, &c.).

2. Theoconus ægæus, Haeckel.

Eucyrtidium ægæum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 31; Mikrogeol., 1854, Taf. xxxv. a, xix. a, fig. 5. Eucyrtidium ægæum, Haeckel, 1862, Monogr. d. Radiol., p. 329.

Shell flatly bell-shaped, nearly conical. Length of the three joints = 2 : 5 : 3; breadth = 1 : 7 : 8. Cephalis ovate, with a stout, straight, pyramidal horn of the same length. Thorax flat, bell-shaped. Abdomen with increasing breadth towards the wide truncated mouth. Pores in all three joints nearly of the same shape, regular, circular, three times as broad as the bars.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.03; breadth, a 0.016, b 0.07, c 0.08.

Habitat.—Mediterranean (Coast of Greece and Sicily), surface.

3. Theoconus zanguebaricus, Haeckel.

Eucyrtidium zanguebaricum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. ix. fig. 22.

Shell bell-shaped. Length of the three joints = 1 : 2 : 1, breadth = 1 : 3 : 4. Cephalis ovate, with a straight, pyramidal horn of half the length. Thorax hemispherical, without collar stricture, but with evident girdle stricture. Abdomen dilated towards the wide truncated mouth. Pores regular, hexagonal, of nearly equal size and form, four to six times as broad as the thin bars.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.03; breadth, a 0.024, b 0.09, c 0.11.

Habitat.—Indian Ocean (off Zanzibar), Pullen, depth 2200 fathoms.

4. Theoconus campanulatus, Haeckel.

? Eucyrtidium campanulatum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 241. Eucyrtidium campanulatum, Haeckel, 1862, Monogr. d. Radiol., p. 329.

Shell bell-shaped, smooth. Length of the three joints = 2 : 3 : 7, breadth = 3 : 7 : 10. Cephalis small, spherical, with a short, conical, oblique horn of the same length. Thorax hemispherical, with an external girdle stricture, prolonged into the truncated, barrel-shaped abdomen, which is a little constricted at the very wide mouth. Pores small and very numerous, regular, circular, twice to three times as broad as the bars.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.07; breadth, a 0.03, b 0.07, c 0.1.

Habitat.—North Atlantic, Station 352, surface.

5. Theoconus orthoconus, n. sp.

Shell perfectly conical, smooth. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 4. Cephalis hemispherical, with a strong, straight, conical horn of the same length. Thorax conical, without external girdle stricture, prolonged into the truncated, conical abdomen, which is gradually dilated into a very wide mouth. Pores small, of nearly equal size and similar form, of the same breadth as the bars.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.03, b 0.06, c 0.12.

Habitat.—Cosmopolitan; Atlantic, Pacific; many stations, at different depths.

Subgenus 2. Theocorbis, Haeckel.

Definition.—Pores of the thorax and of the abdomen of different sizes or dissimilar forms.

6. Theoconus jovis, n. sp. (Pl. 69, fig. 4).

Shell bell-shaped, nearly conical. Length of the three joints = 5 : 6 : 7, breadth = 4 : 10 : 14. Cephalis nearly cylindrical, large, little curved, with a very large, oblique, pyramidal horn, as long as the two first joints together. Thorax and the broader abdomen irregularly bell-shaped, dilated towards the wide mouth. Pores circular, somewhat irregularly disposed, gradually increasing in size towards the mouth.

Dimensions.—Length of the three joints, a 0.05, b 0.06, c 0.07; breadth, a 0.04, b 0.1, c 0.14.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

7. Theoconus junonis, n. sp. (Pl. 69, fig. 7).

Shell nearly conical. Length of the three joints = 4 : 5 : 8, breadth = 3 : 8 : 11. Cephalis ovate, with a large apical opening at the base of the vertical compressed horn, which has about the same length. Thorax and the broader abdomen together conical, gradually dilated towards the wide mouth. Thorax with a bosom-like protuberance on one side. Pores circular, gradually increasing in size.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.08; breadth, a 0.03, b 0.08, c 0.11.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

8. Theoconus longicornis, n. sp.

Shell conical, thorny. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis nearly spherical, with a very large, cylindrical, perpendicular, straight horn, once and a half to twice as long as the whole shell. Thorax conical. Abdomen nearly hemispherical, with wide open mouth. Pores circular, four to six times as broad in the thick-walled spiny abdomen as in the thin-walled rough thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.03, b 0.09, c 0.18.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms; also fossil in Barbados.

9. Theoconus ampullaceus, Haeckel.

Lithocampe ampullacea, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. iv. fig. 1. Theocorys ampullacea, Haeckel, 1881, Prodromus, p. 434.

Shell bell-shaped, nearly conical, thorny. Length of the three joints = 3 : 4 : 10; breadth = 4 : 8 : 15. Cephalis subspherical, with a stout lateral horn of the same length. Thorax hemispherical, rough. Abdomen subspherical, widely truncated at both poles, spiny. Pores regular, circular, three to four times as broad in the thick-walled abdomen as in the thin-walled thorax. (Differs from the similar preceding species in the smaller horn and the two deeper strictures of the shell.)

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.1; breadth, a 0.04, b 0.08, c 0.15.

Habitat.—Fossil in Barbados.

10. Theoconus amplus, Haeckel.

? Podocyrtis ampla, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xvi. fig. 7.

? Podocyrtis ampla, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxiii. fig. 16.

? Eucyrtidium amplum, Ehrenberg, 1873, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 248.

Shell conical, smooth, with two broad internal annular septa. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, with a very large, straight, conical horn of the same breadth, which is as long as the conical thorax. Pores regular, circular, twice as broad in the truncate, gradually dilated abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.12; breadth, a 0.03, b 0.12, c 0.15.

Habitat.—Fossil in Barbados.

11. Theoconus ariadnes, n. sp.

Shell conical, nearly bell-shaped, smooth. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 5. Cephalis subspherical, with a conical spine of about the same length. Thorax hemispherical, thin-walled. Abdomen conical, slightly constricted at the wide open mouth. Pores regular, circular, twice as large in the thick-walled abdomen as in the thin-walled thorax.

Dimensions.—Length of the three joints, a 0.018 to 0.022, b 0.03 to 0.035, c 0.06 to 0.07; breadth, a 0.015 to 0.02, b 0.04 to 0.06, c 0.07 to 0.09.

Habitat.—Cosmopolitan; Atlantic, Indian, and Pacific Oceans, common, surface.

12. Theoconus dionysius, Haeckel.

Thyrsocyrtis dionysia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 5. Thyrsocyrtis jacchia, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 7.

Shell bell-shaped, smooth. Length of the three joints = 1 : 3 : 5, breadth = 1 : 4 : 5. Cephalis subspherical, with a conical, irregularly denticulate horn of twice or thrice the length. Thorax inflated, nearly spherical, truncate at both poles, separated by a deep stricture from the cephalis, as well as from the conical abdomen, which is dilated gradually towards the wide mouth. Pores in the thorax subregular, circular, in the abdomen twice to four times larger, and irregular.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.1; breadth, a 0.02, b 0.08, c 0.1.

Habitat.—Fossil in Barbados.

13. Theoconus laterna, n. sp.

Shell conical, smooth. Length of the three joints = 1 : 2 : 4, breadth = 1 : 2 : 4. Cephalis small, ovate, with a strong, pyramidal, vertical horn three times the length. Thorax hemispherical, with subregular, circular, hexagonally-framed pores. Abdomen truncate, conical, with only fifteen to twenty very large, irregular, polygonal pores, which are separated by very thick bars of the same breadth as the horn.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.03, b 0.07, c 0.12.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

14. Theoconus ficus, Haeckel.

Eucyrtidium ficus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 19. Theocorys ficus, Haeckel, 1881, Prodromus, p. 434.

Shell conical, pear-shaped, smooth. Length of the three joints = 1 : 5 : 20, breadth = 2 : 10 : 25. Cephalis very small, ovate, with a conical, straight horn three times the length. Thorax quite conical, with solid wall, without pores. Abdomen very large, nearly spherical, truncate at both poles, little constricted at the very wide mouth; its pores subregular, circular, about three times as broad as the bars. (This species is intermediate between the genera Theoconus and Theocorys.)

Dimensions.—Length of the three joints, a 0.01, b 0.05, c 0.2; breadth, a 0.02, b 0.1, c 0.25.

Habitat.—Fossil in Barbados.

Genus 614. Lophoconus,^[119] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with conical abdomen gradually dilated towards the wide open mouth. Cephalis with two or more horns or a corona of horns.

The genus Lophoconus has the same conical shell with truncate mouth as Theoconus, and differs from it only in the armature of the cephalis, bearing either two large divergent horns (usually a larger occipital and a smaller frontal horns), or a bunch or corona of numerous divergent horns.

1. Lophoconus antilope, Haeckel.

Eucyrtidium antilope, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ix. fig. 18.

Shell conical, smooth, with two slight strictures. Length of the three joints = 1 : 3 : 8, breadth = 2 : 4 : 8. Cephalis hemispherical, with two divergent, pyramidal horns of twice the length. Thorax campanulate. Abdomen gradually dilated towards the wide open mouth. Pores very small and numerous, regular, hexagonal.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.12; breadth, a 0.025, b 0.07, c 0.12.

Habitat.—Indian Ocean; between Aden and Socotra (Haeckel); Zanzibar (Pullen).

2. Lophoconus hexagonalis, n. sp.

Shell campanulate, conical, spiny, with two sharp strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis hemispherical, with numerous conical spines of different sizes, the largest of twice the length. Thorax campanulate, with smaller spines. Abdomen inflated, dilated towards the wide mouth. Pores large, three or four times as broad as the bars, subregular, hexagonal.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.09; breadth, a 0.03, b 0.07, c 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

3. Lophoconus cornutella, n. sp.

Shell slender, conical, smooth, without external strictures, but with two internal, annular septa. Length of the three joints = 1 : 2 : 6, breadth = 1 : 2 : 4. Cephalis ovate, with two stout, divergent, conical horns of three times the length. Thorax and abdomen together conical, gradually dilated towards the wide truncate mouth. Pores regular, circular, quincuncial.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.12; breadth, a 0.02, b 0.04, c 0.08.

Habitat.—North Atlantic, Station 353, depth 2965 fathoms.

4. Lophoconus apiculatus, Haeckel.

Eucyrtidium apiculatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 10.

Shell campanulate, conical, thorny, with two distinct strictures. Length of the three joints = 1 : 2 : 2, breadth = 1 : 3 : 4. Cephalis subspherical, with a bunch of eight to twelve divergent, conical horns, the largest of which are longer than the cephalis. The regular, circular pores are in the campanulate thorax scarcely half as broad as in the truncate, gradually dilated abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.04; breadth, a 0.025, b 0.06, c 0.08.

Habitat.—Fossil in Barbados.

5. Lophoconus cervus, Haeckel

? Eucyrtidium cervus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ix. fig. 21.

Shell conical, smooth, without external stricture, but with two internal annular septa. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 6. Cephalis campanulate, with two to six divergent, partly ramified horns. Pores in the thorax regular, circular, in the abdomen three to four times as large, regular, hexagonal.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.02, b 0.06, c 0.12.

Habitat.—Indian Ocean, Cocos Islands (Rabbe), surface (? Zanzibar, 2200 fathoms, Pullen).

6. Lophoconus rhinoceros, n. sp. (Pl. 69, fig. 2).

Shell campanulate, conical, rough, with two sharp strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis subspherical, with numerous very small pores, and two stout, divergent, pyramidal horns, the major of which is longer, the minor shorter, than the cephalis. Thorax campanulate, with small, regular, circular pores. Abdomen inflated, with thickened margin at the wide open mouth, and with irregular, roundish pores, twice to four times as broad as those of the thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.09; breadth, a 0.04, b 0.09, c 0.12.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 615. Theocyrtis,^[120] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with cylindrical abdomen, and wide open truncate mouth. Cephalis with a single horn.

The genus Theocyrtis and the three following closely allied genera differ from the other Theocorida in the cylindrical form of the slender abdomen, which is of equal breadth nearly throughout its whole length. The terminal mouth is wide open, usually truncate, and of the same breadth; sometimes slightly constricted. The cephalis of Theocyrtis bears a single horn.

Subgenus 1. Theocorypha, Haeckel.

Definition.—Pores of the thorax and abdomen of nearly equal size and similar form.

1. Theocyrtis trachelius, Haeckel.

Eucyrtidium trachelius, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 8.

Shell thin-walled and very fragile, smooth. Length of the three joints = 2 : 8 : 7, breadth = 2 : 9 : 8. Cephalis subspherical, with a straight, conical horn of the same length, separated by a slender neck from the inflated, subspherical thorax. Abdomen cylindrical, with a wide open, truncate mouth. Pores subregular, hexagonal, of equal size, four to six times as broad as the thin, thread-like bars.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.07; breadth, a 0.02, b 0.09, c 0.08.

Habitat.—Tropical Pacific, many Stations (200, 224, 271, &c.), surface, and in various depths.

2. Theocyrtis barbadensis, Haeckel.

Eucyrtidium barbadense, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. ix. fig. 7.

Shell thin-walled, smooth. Length of the three joints = 2 : 4 : 5, breadth, 2 : 5 : 4. Cephalis ovate or conical, with a strong, conical horn, without external stricture, dilated into the campanulate thorax. Abdomen cylindrical, with a wide open, truncate mouth. Pores subregular, circular, quincuncially disposed, of about the same breadth as the bars.

Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.1; breadth, a 0.04, b 0.1, c 0.08.

Habitat.—Fossil in the Tertiary rocks of Barbados.

3. Theocyrtis cylindrica, Haeckel.

Eucyrtidium cylindricum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 1.

Shell elongate, cylindrical, straight, smooth. Length of the three joints = 1 : 2 : 6, breadth = 1 : 3 : 3. Cephalis hemispherical, with a thick, pyramidal horn of the same length (the edges of the horn giving to it the appearance of being composed of two converging spines). Thorax truncated, conical. Abdomen perfectly cylindrical, much elongated. Pores subregular, circular, twice as broad as the bars, quincuncially disposed. Mouth wide open, truncate.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.12; breadth, a 0.03, b 0.06, c 0.06.

Habitat.—Tropical Pacific, Station 266, depth 2750 fathoms; fossil in Barbados.

4. Theocyrtis elegans, Haeckel.

Eucyrtidium elegans, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 12. ? Eucyrtidium pusillum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 6

Shell slender, cylindrical, straight, smooth. Length of the three joints = 1 : 2 : 7, breadth = 1 : 3 : 3. Cephalis subconical, with a small conical horn. Thorax campanulate, conical. Abdomen cylindrical, very slender. Pores subregular, circular, small, disposed in transverse rows, three in the thorax, six to eight in the abdomen. Mouth wide open, truncate.

Dimensions.—Length of the three joints, a 0.01, b 0.02, c 0.07; breadth, a 0.015, b 0.03, c 0.03.

Habitat.—Fossil in Barbados and Sicily.

5. Theocyrtis paupera, Haeckel.

Eucyrtidium pauperum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 13.

Shell slender, cylindrical, smooth. Length of the three joints = 1 : 2 : 6, breadth = 1 : 3 : 3. Cephalis hemispherical, with a stout conical horn of twice the length. Thorax truncate, conical. Abdomen cylindrical. Pores very small, regular, circular, disposed in transverse rows, one or two in the thorax, three to five in the abdomen. (Distance between the rows twice as great as in the preceding nearly related species.) Mouth wide open, truncate.

Dimensions.—Length of the three joints, a 0.01, b 0.02, c 0.06; breadth, a 0.015, b 0.03, c 0.03.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms; also fossil in Barbados and Sicily.

6. Theocyrtis microtheca, Haeckel.

Eucyrtidium microtheca, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 10. Eucyrtidium hillaby, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 8.

Shell cylindrical, a little rough. Length of the three joints = 1 : 3 : 4, breadth = 1 : 3 : 3. Cephalis subspherical, with a small conical horn. Thorax hemispherical or campanulate. Abdomen cylindrical, with wide open truncate mouth. Pores subregular, circular, quincuncially disposed, of medium size, rudimentary or wanting in the cephalis.

Dimensions.—Length of the three joints, a 0.015 to 0.02, b 0.03 to 0.05, c 0.05 to 0.08; breadth, a 0.02 to 0.025, b 0.05 to 0.06, c 0.05 to 0.06.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms; also fossil in Barbados.

Subgenus 2. Theocorusca, Haeckel.

Definition.—Pores of the thorax and the abdomen of different sizes or forms.

7. Theocyrtis macroceros, n. sp. (Pl. 69, fig. 13).

Shell almost cylindrical, smooth. Length of the three joints = 1 : 2 : 5, breadth = 2 : 3 : 4. Cephalis hemispherical, with a very large cylindrical horn, once or twice as long as the shell. Thorax truncate, hemispherical. Abdomen cylindrical, only slightly contracted towards both ends. Two girdle strictures deep. Pores small, subregular, circular, more irregular and twice to three times as large in the abdomen as in the thorax, disposed in transverse rows, five to six in the thorax, eight to ten in the abdomen.

Dimensions.—Length of the three joints, a 0.02 to 0.03, b 0.04 to 0.05, c 0.1 to 0.12; breadth, a, 0.04, b 0.07, c 0.08.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms; also fossil in Barbados.

8. Theocyrtis ptychodes, n. sp. (Pl. 69, fig. 8).

Shell almost cylindrical, smooth. Length of the three joints = 1 : 3 : 3, breadth = 2 : 4 : 4. Cephalis hemispherical, with a large, conical, curved horn of twice the length. Thorax very large, inflated, campanulate, thick-walled. Abdomen cylindrical, with a thin folded wall (like a petticoat), the thickness of which decreases gradually towards the wide truncate mouth. Pores subregular, circular, and quincuncially disposed in the two first joints, irregular and larger in the abdomen, forming longitudinal series between the folds.

Dimensions.—Length of the three joints, a 0.04, b 0.1, c 0.11; breadth, a 0.05, b 0.12, c 0.12.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

9. Theocyrtis aspera, Haeckel.

Eucyrtidium asperum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. viii. fig. 15.

Shell almost cylindrical, with rough or thorny surface. Length of the three joints = 1 : 3 : 5, breadth = 1 : 5 : 5. Cephalis subspherical, small, with a short conical horn. Thorax hemispherical, inflated. Abdomen cylindrical, with wide truncate mouth. Pores in the thorax subregular, circular, quincuncially disposed, in the abdomen irregular roundish, two to four times as large.

Dimensions.—Length of the three joints, a 0.015 to 0.02, b 0.06 to 0.07, c 0.08 to 0.1; breadth, a 0.02, b 0.1, c 0.1.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms; fossil in Barbados.

10. Theocyrtis proserpinæ, n. sp.

Shell almost cylindrical, smooth. Length of the three joints = 3 : 6 : 9, breadth = 2 : 8 : 7. Cephalis subspherical, with a stout conical horn. Thorax campanulate. Abdomen cylindrical. Pores regular, circular, quincuncially disposed, double-edged in the thorax, and three to four times as large as in the cephalis and the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.02, b 0.08, c 0.07.

Habitat.—North Pacific, Stations 244 to 253, depth 2050 to 3125 fathoms.

11. Theocyrtis oenophila, Haeckel.

Thyrsocyrtis oenophila, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 8.

Shell in the apical half conical, in the lower cylindrical. Length of the three joints = 2 : 5 : 6, breadth = 3 : 8 : 7. Cephalis subspherical, with a large prismatic horn, which is bulbous at the base, and armed with three teeth at the distal apex. Thorax conical, constricted at the base, with subregular, circular, quincuncial pores. Abdomen cylindrical, with a coronal of nine large roundish pores beyond the lumbar stricture, and two to four succeeding transverse rows of irregular, roundish, smaller pores. Mouth widely open, truncated.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.06; breadth, a 0.03, b 0.08, c 0.07.

Habitat.—Fossil in Barbados.

Genus 616. Theosyringium, Haeckel,^[121] 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with cylindrical abdomen, which is much narrower than the inflated thorax, and forms a slender, narrow tube, with truncated mouth. Cephalis with a single horn.

The genus Theosyringium differs from the closely allied Theocyrtis, its ancestral form, in the wide inflated thorax, which is much broader than the narrow tubular abdomen. The mouth of the latter is small and truncate.

1. Theosyringium tibia, n. sp. (Pl. 68, fig. 4).

Shell rough, very slender, with two distinct strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 2 : 1. Cephalis ovate, with a conical horn of the same length. Thorax ellipsoidal. Abdomen cylindrical, as long as the two former joints together. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.12; breadth, a 0.03, b 0.06, c 0.02.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

2. Theosyringium pipetta, n. sp. (Pl. 68, fig. 5).

Shell rough, inflated, with two sharp strictures. Length of the three joints = 2 : 7 : 9, breadth = 2 : 7 : 2. Cephalis conical, with a slender horn of half the length. Thorax subglobose. Abdomen cylindrical, as long as the two former joints together. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.09; breadth, a 0.02, b 0.07, c 0.02.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Theosyringium siphonium, n. sp.

Shell rough, inflated, with two deep strictures. Length of the three joints = 1 : 3 : 3, breadth = 1 : 2 : 1. Cephalis subspherical, with a stout pyramidal horn of twice the length. Thorax broad ovate. Abdomen slender, inversely conical, as long as the thorax, and one-third as broad as the base. Pores subregular, circular, hexagonally framed, (Similar to Eusyringium conosiphon, Pl. 78, fig. 10, but only with two strictures and three joints.)

Dimensions.—Length of the three joints, a 0.03, b 0.1, c 0.1; breadth, a 0.03, b 0.07, c 0.025.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

4. Theosyringium tubulus, Haeckel.

Eucyrtidium tubulus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 6.

Shell smooth, slenderly spindle-shaped, with two slight strictures. Length of the three joints = 2 : 10 : 8, breadth = 3 : 6 : 3. Cephalis hemispherical, hyaline, with a stout, pyramidal horn of the same length. Thorax spindle-shaped. Abdomen inversely conical, half as long as the thorax prolonged into a slender, cylindrical tube. Pores subregular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.1, c 0.08; breadth, a 0.03, b 0.06, c 0.03.

Habitat.—Fossil in Barbados.

Genus 617. Lophocyrtis,^[122] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with cylindrical abdomen, and wide open truncate mouth. Cephalis with two horns, or a bunch of horns.

The genus Lophocyrtis differs from its ancestral form Theocyrtis only in the armature of the cephalis, bearing instead of a single horn either two divergent horns, or a bunch, or coronal of numerous spines. The slender abdomen is in both genera cylindrical, with wide open mouth.

1. Lophocyrtis holothuria, n. sp.

Shell smooth, slender, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 2 : 4 : 3. Cephalis hemispherical, with a bunch of five divergent, conical horns, the middle of which is larger and vertical, nearly as long as the thorax. Thorax campanulate, half as long as the cylindrical abdomen. Mouth truncate. Pores regular, circular, quincuncial. (Similar to Theocyrtis cylindrica, but with different cephalis and thorax.)

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.1; breadth, a 0.04, b 0.07, c 0.06.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Lophocyrtis stephanophora, Haeckel.

Eucyrtidium stephanophorum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin p. 72, Taf. viii. fig. 14.

Shell smooth, slender, with deep collar and indistinct lumbar stricture. Length of the three joints = 1 : 2 : 4, breadth = 1 : 3 : 3. Cephalis subspherical, with very small circular pores, and a corona of three to nine short conical spines. Thorax campanulate, with regular, circular pores, which are half or one-third as broad as those of the cylindrical abdomen.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.09; breadth, a 0.025, b 0.06, c 0.06.

Habitat.—Fossil in Barbados.

3. Lophocyrtis synapta, n. sp. Pl. 68, fig. 15.

Shell spiny, with two sharp strictures. Length of the three joints = 5 : 10 : 6, breadth = 4 : 9 : 7. Cephalis large, ovate, with numerous (twenty to thirty or more) conical, radially divergent spines of different sizes, the largest about as long as the cephalis. Thorax subconical, with numerous short, conical, divergent spines, which are directed downwards. Abdomen smooth, cylindrical. The irregular, polygonal pores are separated by thin bars, and in the thorax are twice to four times as broad as in the first and last joints.

Dimensions.—Length of the three joints, a 0.05, b 0.1, c 0.06; breadth, a 0.04, b 0.09, c 0.07.

Habitat.—Indian Ocean, Maldive Islands (Haeckel), surface.

4. Lophocyrtis coronata, Haeckel.

Eucyrtidium coronatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 9.

Shell smooth, cylindrical, with two deep strictures. Length of the three joints = 4 : 3 : 4, breadth = 4 : 5 : 4. Cephalis subspherical, large, of about the same size and form as the thorax, with a coronal of four to eight short, conical spines on the apex. Pores in the two first joints irregular, roundish, twice to four times as broad as the small, circular pores of the cylindrical abdomen, which are disposed in four to eight transverse rows.

Dimensions.—Length of the three joints, a 0.04, b 0.03, c 0.04; breadth, a 0.04, b 0.05, c 0.04.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms; fossil in Barbados.

5. Lophocyrtis biaurita, Haeckel.

Eucyrtidium biauritum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 8. Eucyrtidium biauritum, Bütschli, 1882, Zeitschr. f. wiss. Zool., p. 540, Taf. xxxiii. fig. 38, a-f.

Shell smooth, with two distinct strictures. Length of the three joints = 1 : 6 : 3, breadth = 2 : 5 : 4. Cephalis small, hemispherical, hyaline, with two large, divergent, curved horns of three times the length. Thorax ovate, with few small, widely scattered pores. Abdomen cylindrical, without pores.

Dimensions.—Length of the three joints, a 0.015, b 0.06, c 0.03; breadth, a 0.02, b 0.05, c 0.04.

Habitat.—Fossil in Barbados.

Genus 618. Tricolocampe,^[123] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta), with cylindrical abdomen, and wide open truncate mouth. Cephalis without horn.

The genus Tricolocampe differs from its ancestral genus, Theocyrtis, in the loss of the cephalic horn; it has the same cylindrical form of the slender abdomen, and a wide open terminal mouth of the same breadth. The whole shell is more or less cylindrical, (sometimes conical in the upper part), with two distinct external strictures, or internal annular septa.

Subgenus 1. Tricolocampium, Haeckel.

Definition.—Pores of the thorax and of the abdomen of nearly equal size and similar form.

1. Tricolocampe cylindrica, n. sp. (Pl. 66, fig. 21).

Shell nearly cylindrical, smooth. Length of the three joints = 2 : 3 : 15, breadth = 3 : 4 : 5. Cephalis hemispherical, with numerous very small pores. Thorax and abdomen cylindrical, of about equal breadth, with equal, circular pores, disposed regularly in transverse rows, three to four rows in the thorax, ten to twelve in the abdomen. Mouth wide open, not constricted.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.15; breadth, a 0.03, b 0.04, c 0.05.

Habitat.—Central Pacific, Stations 265 to 274, depth 2350 to 2925 fathoms.

2. Tricolocampe pupa, Haeckel.

Eucyrtidium pupa, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 16.

Shell nearly cylindrical, smooth. Length of the three joints = 2 : 2 : 8, breadth = 2 : 3 : 3. Cephalis subspherical, with four larger pores. Thorax and abdomen cylindrical, of about equal breadth, with equal, very small pores, disposed regularly in transverse rows, two rows in the thorax, eight to ten in the abdomen. Mouth wide open, a little constricted.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.08; breadth, a 0.02, b 0.03, c 0.03.

Habitat.—Tropical Pacific (Philippine Sea), Station 206, depth 2100 fathoms.

3. Tricolocampe polyzona, n. sp. (Pl. 66, fig. 19).

Shell nearly cylindrical, thick-walled. Length of the three joints = 4 : 4 : 12, breadth = 8 : 9 : 9. Cephalis obtuse, conical. Thorax barrel-shaped. Abdomen in the middle part a little constricted. Pores very numerous, subregular, disposed regularly in transverse rows, six to eight in the cephalis, eight to ten in the thorax, twelve to fifteen in the abdomen. Mouth rather constricted, only half as broad as the abdomen.

Dimensions.—Length of the three joints, a 0.04, b 0.04, c 0.12; breadth, a 0.08, b 0.09, c 0.09.

Habitat.—Central Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms; also fossil in the Nicobars and in Barbados.

4. Tricolocampe stenozona, n. sp. (Pl. 66, fig. 20).

Shell nearly cylindrical, thin-walled. Length of the three joints = 5 : 4 : 9, breadth = 6 : 8 : 9. Form of the three joints and disposition of their pores nearly equal to the preceding species; but the proportion of the joints is different, the shell more delicate, and the mouth more widely open, and nearly as broad as the abdomen.

Dimensions.—Length of the three joints, a 0.05, b 0.04, c 0.09; breadth, a 0.06, b 0.08, c 0.09.

Habitat.—North Pacific, Station 256, depth 2950 fathoms.

5. Tricolocampe amphizona, n. sp. (Pl. 66, fig. 17).

Shell mitre-shaped, very thick-walled. Length of the three joints = 2 : 1 : 1, breadth nearly uniform. Cephalis obtuse, conical, as long as the two other cylindrical joints together (probably composed of several united joints). Pores subregular, disposed in transverse rows, six to eight in the cephalis, two in the thorax, and two in the abdomen. Mouth widely open.

Dimensions.—Length of the three joints, a 0.04, b 0.02, c 0.02; breadth, a 0.04, b 0.05, c 0.05.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

6. Tricolocampe panthera, Haeckel.

Eucyrtidium panthera, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 18.

Shell mitre-shaped or nearly cylindrical, thick-walled. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 2. Cephalis subspherical. Thorax campanulate. Abdomen cylindrical. Pores in all three joints irregular, roundish, of different sizes, irregularly disposed. Mouth widely open, truncated, not constricted.

Dimensions.—Length of the three joints, a 0.015 to 0.02, b 0.04 to 0.05, c 0.06 to 0.08; breadth about a 0.02, b and c 0.05.

Habitat.—Cosmopolitan; Atlantic, Pacific; also fossil in Barbados.

Subgenus 2. Tricolocamptra, Haeckel.

Definition.—Pores of the thorax and the abdomen of different sizes or forms.

7. Tricolocampe urnula, n. sp. (Pl. 66, fig. 22).

Shell cylindrical, with obtuse conical apex, smooth. Length of the three joints = 2 : 3 : 10, breadth = 2 : 3 : 6. Cephalis subspherical. Thorax barrel-shaped. Abdomen cylindrical with slightly constricted wide mouth. Pores irregular, roundish, three to four times as broad in the abdomen as in the thorax, irregularly disposed.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.1; breadth, a 0.025, b 0.035, c 0.06.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

8. Tricolocampe doliolum, n. sp.

Shell cylindrical, with hemispherical apex, rough. Length of the three joints = 1 : 3 : 5, breadth = 1 : 2 : 3. Cephalis spherical. Thorax and abdomen cylindrical, of nearly equal breadth. Mouth widely open, not constricted. Pores irregular, roundish, in the abdomen three to four times as large as in the thorax, disposed in oblique rows.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.16; breadth, a 0.03, b 0.05, c 0.09.

Habitat.—Fossil in Barbados.

9. Tricolocampe cingulata, n. sp.

Shell subcylindrical, with obtuse conical apex, thick-walled. Length of the three joints = 2 : 3 : 11, breadth = 3 : 7 : 8. Cephalis hemispherical, not separated externally from the short conical thorax, but with internal collar septum. Abdomen cylindrical, with wide open, non-constricted mouth. Pores in the thorax narrow, obliquely ascending, in the abdomen twice as large, circular, arranged in ten to twelve regular transverse rows, separated by slight strictures. Lumbar septum nearly complete.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.1 to 0.12; breadth, a 0.03, b 0.07, c 0.08.

Habitat.—Fossil in Barbados, and in Tertiary rocks of Sicily; living in the depths of the Atlantic and Central Pacific, Station 348, depth 2450 fathoms; Station 268, depth 2900 fathoms.

10. Tricolocampe arcta, Haeckel.

? Eucyrtidium arctum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 33. ? Lithocampe arcta, Haeckel, 1862, Monogr. d. Radiol., p. 317.

Shell subcylindrical, with obtuse conical apex. Length of the three joints = 1 : 2 : 4, breadth = 1 : 2 : 2. Cephalis subspherical. Thorax campanulate, separated by a deep collar, but a slight lumbar stricture. Abdomen cylindrical, with wide truncate mouth. Pores in the thorax narrow, obliquely ascending, in the abdomen half as large, very small, and densely disposed in six to eight regular transverse rows.

Dimensions.—Length of the three joints, a 0.022, b 0.045, c 0.09; breadth, a 0.026, b 0.05, c 0.05.

Habitat.—Central Pacific, Station 266 to 274, depth 2350 to 2925 fathoms.

Genus 619. Theocorys,^[124] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with ovate abdomen, broader than the constricted mouth. Cephalis with a single horn.

The genus Theocorys and the two following closely allied genera, united formerly with Eucyrtidium, differ from the preceding Theocorida in the constriction of the peristome, so that the inflated abdomen is broader than the terminal mouth. They represent, therefore, the transition to the Theocapsida, with closed mouth. The abdomen is commonly more or less ovate or barrel-shaped, sometimes inversely conical. The cephalis of Theocorys bears a single apical horn.

Subgenus 1. Theocoronium, Haeckel.

Definition.—Pores of the thorax and of the abdomen of nearly equal size and similar form.

1. Theocorys turgidula, Haeckel.

Eucyrtidium turgidulum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 13.

Shell slender, ovate, with two deep strictures, very fragile and thin-walled. Length of the three joints = 2 : 5 : 7, breadth = 2 : 6 : 6. Cephalis subspherical, with a pyramidal horn of the same length. Thorax nearly spherical. Abdomen ovate, twice as broad as the constricted mouth. Pores very numerous, regular hexagonal, three to four times as broad as the bars.

Dimensions.—Length of the three joints, a 0.015, b 0.05, c 0.07; breadth, a 0.02, b 0.06, c 0.06.

Habitat.—Tropical Pacific (Philippine Sea), Stations 206 and 224, surface.

2. Theocorys veneris, n. sp. (Pl. 69, fig. 5).

Shell inversely ovate, with two deep strictures, smooth. Length of the three joints = 2 : 5 : 6, breadth = 3 : 7 : 6. Cephalis hemispherical, with a slender conical horn of twice the length. Thorax nearly spherical. Abdomen ovate, twice as broad as the constricted mouth. Pores regular, circular, twice as broad as the bars, quincuncially disposed.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.06; breadth, a 0.03, b 0.07, c 0.06.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific; many Stations, surface.

3. Theocorys cretica, Haeckel.

Eucyrtidium creticum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. xi. fig. 23.

Shell ovate, thin-walled, smooth, with two deep strictures. Length of the three joints = 2 : 4 : 4, breadth = 3 : 6 : 6. Cephalis hemispherical, with a conical horn of the same length. Thorax and abdomen nearly hemispherical, inflated, united by the opposite bases of the hemispheres. Constricted mouth only one-third as broad as the abdomen. Pores very small and numerous, regular, circular, of the same breadth as the bars, quincuncially disposed.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.04; breadth, a 0.03, b 0.06, c 0.06.

Habitat.—Mediterranean, Crete, Corfu, surface.

4. Theocorys ovata, n. sp. (Pl. 69, fig. 16).

Shell quite ovate, thick-walled, smooth, without external strictures. Length of the three joints = 2 : 2 : 9. breadth = 3 : 5 : 7. Cephalis conical, with a thick conical horn of the same length. Thorax and abdomen gradually dilated towards the base, and then hemispherical, constricted. Mouth scarcely one-third as broad as the abdomen, prolonged into a short tube. Pores regular, circular, disposed in transverse rows, two to three in the cephalis, two to three in the thorax, eight to ten in the abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.09; breadth, a 0.03, b 0.05, c 0.07.

Habitat.—Central Pacific, Stations 263 to 268, depth 2650 to 3000 fathoms.

5. Theocorys plutonis, n. sp. (Pl. 69, fig. 1).

Shell ovate, thick-walled, smooth, with two slight strictures. Length of the three joints = 2 : 5 : 4, breadth = 4 : 7 : 6. Cephalis hemispherical, with a conical, oblique horn of the same length. Thorax and abdomen only slightly inflated, gradually decreasing towards the wide, little constricted mouth. Pores subregular, circular, much larger in the abdomen and the lower half of the thorax than in the upper half and the cephalis.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.04; breadth, a 0.04, b 0.07, c 0.06.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

6. Theocorys scolopax, Haeckel.

Eucyrtidium scolopax, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 5.

Shell slender, inversely ovate, smooth. Length of the three joints = 1 : 3 : 3, breadth = 1 : 4 : 4. Cephalis subspherical, with a long, slightly curved horn, half as long as the whole shell. Thorax campanulate. Abdomen inversely ovate, twice as broad as the constricted mouth (incomplete in Ehrenberg's figure).

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.06; breadth, a 0.02, b 0.08, c 0.08.

Habitat.—Fossil in Barbados.

Subgenus 2. Theocorythium, Haeckel.

Definition.—Pores of the thorax and of the abdomen of different sizes or dissimilar forms.

7. Theocorys dianæ, n. sp. (Pl. 69, fig. 11).

Shell almost ovate, with two deep strictures. Length of the three joints = 3 : 6 : 8, breadth = 3 : 9 : 8. Cephalis subspherical, with a slender, pyramidal horn of three times the length. Thorax conical, constricted at the base. Abdomen bottle-shaped. Pores in the thorax irregular, polygonal, in the abdomen subregular, circular, quincuncially disposed.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.08; breadth, a 0.03, b 0.09, c 0.08.

Habitat.—North Pacific, Station 253, surface.

8. Theocorys hyalothorax, n. sp.

Shell slender, ovate, with two deep strictures. Length of the three joints = 6 : 9 : 8, breadth = 7 : 12 : 11. Cephalis subspherical, with numerous densely-placed circular pores, and with a pyramidal, slender horn of the same length. Thorax hemispherical, hyaline, without any pores. Abdomen ovate, twice as broad as the constricted mouth, with two to four widely distant, transverse rows of small, circular pores.

Dimensions.—Length of the three joints, a 0.024, b 0.036, c 0.032; breadth, a 0.028, b 0.048, c 0.044.

Habitat.—Tropical Pacific, Station 225, depth 4475 fathoms.

9. Theocorys bachabunda, Haeckel.

Thyrsocyrtis bachabunda, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 4.

Shell inversely ovate, with two distinct strictures. Length of the three joints = 2 : 5 : 9, breadth = 3 : 9 : 8. Cephalis subspherical, small, with a large cylindrical horn, which is half as long as the whole shell, and armed with spines at the conical apex. Thorax conical, inflated, with small, subregular, circular, quincuncial pores. Abdomen inversely ovate, with irregular, roundish, pores of larger and smaller sizes mixed, gradually lessening towards the constricted mouth.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.09; breadth, a 0.03, b 0.09, c 0.08.

Habitat.—Fossil in Barbados.

10. Theocorys attenuata, Haeckel.

Eucyrtidium attenuatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 16.

Shell inversely ovate, with distinct collar, but indistinct lumbar stricture. Length of the three joints = 2 : 5 : 5, breadth = 2 : 7 : 6. Cephalis hemispherical, with a short, oblique, conical horn. Thorax inflated, campanulate, with small, regular, circular, quincuncial pores. Abdomen inversely conical, with irregular pores of larger and smaller sizes mixed, gradually lessening towards the truncated mouth.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.05; breadth, a 0.025, b 0.07, c 0.06.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

11. Theocorys obliqua, n. sp. (Pl. 69, fig. 10).

Shell inversely ovate, with distinct collar, but indistinct lumbar stricture. Length of the three joints = 3 : 7 : 4, breadth = 4 : 9 : 8. Cephalis hemispherical, with a stout, pyramidal, oblique horn of the same length. Thorax and abdomen together ovate, gradually lessening towards the constricted mouth, which is only half as broad. Pores irregular, roundish, in the thorax twice to four times as broad as in the abdomen. Both joints are separated by an oblique, internal, lumbar septum, which in some specimens observed was more oblique than in that figured; some specimens had a very irregular form.

Dimensions.—Length of the three joints, a 0.025 to 0.03, b 0.06 to 0.07, c 0.03 to 0.04; breadth, a 0.04, b 0.09, c 0.08.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms; also fossil in Barbados.

12. Theocorys alauda, Haeckel.

Eucyrtidium alauda, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 4.

Shell nearly spindle-shaped, decreasing from the thicker middle towards both ends. Length of the three joints = 1 : 3 : 8, breadth = 1 : 4 : 5. Cephalis subspherical, with a strong, conical horn of three times the length. Thorax campanulate, with numerous regular, circular, quincuncial pores. Abdomen inversely ovate, slender, twice as broad as the truncated mouth, with irregular, roundish pores, three to four times as large as those of the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.16; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Fossil in Barbados and in Tertiary rocks of Sicily.

13. Theocorys apollinis, n. sp. (Pl. 69, fig. 3).

Shell ovate, with two deep strictures. Length of the three joints = 2 : 3 : 5, breadth = 2 : 5 : 7. Cephalis subspherical, with a large, straight, cylindrical horn, about as long as the whole shell (in the specimen figured this is broken off). Thorax truncate, conical. Abdomen subglobose, truncate on both poles, twice as broad as the constricted mouth. Pores quincuncial, subregular, circular, twice as broad in the abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.05; breadth, a 0.02, b 0.05, c 0.07.

Habitat.—South Atlantic, Station 332, surface.

14. Theocorys sphærophila, Haeckel.

Eucyrtidium sphærophilum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. viii. fig. 16.

Shell almost ovate, rough, with two slight strictures. Length of the three joints = 2 : 7 : 10, breadth = 3 : 8 : 12. Cephalis subspherical, with a strong, conical horn of the same length. Thorax nearly spherical, with subregular, circular pores of different sizes. Abdomen ovate, truncate at both poles, nearly twice as broad as the constricted mouth, with very large, subregular, hexagonal pores, four to six times as broad as the bars, in three to four transverse, and ten to twelve longitudinal rows.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.1; breadth, a 0.03, b 0.08, c 0.12.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms; fossil in Barbados.

15. Theocorys tuberculata, n. sp.

Shell almost ovate, tuberculate, with deep collar, but slight lumbar stricture. Length of the three joints = 2 : 5 : 12, breadth = 3 : 8 : 11. Cephalis hemispherical, with a cylindrical horn of twice the length. Thorax hemispherical, with regular, circular, double-edged, quincuncial pores, between which conical tubercles occur. Abdomen truncate, ovate, twice as broad as the constricted mouth, with regular, circular, hexagonally-framed pores, three to four times as broad as those of the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.12; breadth, a 0.03, b 0.08, c 0.11.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms; fossil in Barbados.

16. Theocorys martis, n. sp.

Shell slender, ovate, with two deep strictures. Length of the three joints = 3 : 6 : 18, breadth = 4 : 8 : 12. Cephalis small, hemispherical, with a very large, sword-shaped broad horn, nearly as long as the whole shell. Thorax hemispherical, honey-comb like, with regular, circular, hexagonally-framed pores. Abdomen ovate, with irregular, roundish, very large pores, four to six times as broad as the bars, and as the pores of the thorax. Constricted mouth half as broad as the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.18; breadth, a 0.04, b 0.08, c 0.12.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

17. Theocorys mercurii, n. sp.

Shell ovate, conical, with two slight strictures. Length of the three joints = 1 : 3 : 7, breadth = 2 : 4 : 7. Cephalis hemispherical, with a broad pyramidal horn of the same length. Thorax campanulate, with longitudinal series of small, regular, circular pores, separated by divergent crests. Abdomen nearly spherical, one and a half times as broad as the constricted mouth, which is prolonged into a thin, solid, cylindrical peristome. Pores of the abdomen regular, circular, hexagonally framed, three to four times as broad as the bars, and as the pores of the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.15; breadth, a 0.04, b 0.09, c 0.15.

Habitat.—South Atlantic, Station 338, depth 1990 fathoms.

18. Theocorys minervæ, n. sp. (Pl. 69, fig. 14).

Shell ovate, conical, with two deep strictures. Length of the three joints = 1 : 3 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, with a large pyramidal horn as long as the thorax, and with small, circular pores. Thorax rough, with regular, quincuncial, circular pores, three to four times as large as those of the cephalis. Abdomen barrel-shaped, with irregular, roundish pores of very different sizes, six very large pores immediately beyond the lumbar stricture, and four to five rows of pores, which are twice to four times as large as those of the thorax. Mouth truncated, with thickened margin, two-thirds as broad as the abdomen.

Dimensions.—Length of the three joints, a 0.04, b 0.12, c 0.16; breadth, a 0.04, b 0.16, c 0.2.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 620. Axocorys,^[125] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta), with ovate abdomen, including an internal vertical axial rod, which bears three divergent radial spines or verticils of three branches, and is prolonged into an apical horn.

The genus Axocorys contains only a single but very remarkable species, and may, perhaps, represent a peculiar group, which has closer relations to the Plectoidea than to the other Tricyrtida. The pyriform three-jointed shell has neither lateral nor terminal free appendages, but possesses a very large apical horn, and an inner prolongation of this, an axial rod, which bears some triradiate verticils of branched spines. The original ancestral forms of this remarkable genus are probably Plagoniscus and Plectaniscus (pp. 912 and 924).

1. Axocorys macroceros, n. sp. (Pl. 68, figs. 1, 1a).

Shell pear-shaped, with two distinct strictures. Length of the three joints = 2 : 3 : 16, breadth = 3 : 6 : 16. Cephalis hemispherical, with few small pores. From its apex arises vertically a very long three-sided prismatic horn with denticulate edges, three to four times as long as the shell. An inner thin prolongation of the horn descends vertically nearly to the mouth, and bears on its basal end three verticils of branched spines, each verticil with three divergent forked spines (fig. 1a). Pores regular, circular, in the subspherical abdomen three times as large as in the hemispherical thorax. The constricted mouth is scarcely broader than the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.16; breadth a 0.03, b 0.06, c 0.16.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 621. Lophocorys,^[126] Haeckel, 1881, Prodromus, p. 434.

Definition.—Theocorida (vel Tricyrtida eradiata aperta), with ovate abdomen, broader than the constricted mouth. Cephalis with two divergent horns, or with a bunch of horns.

The genus Lophocorys differs from its ancestral form, Theocorys, only in the armature of the cephalis, bearing either two divergent horns, or a corona of several radial horns. In two species there are four horns on the apex, a larger vertical (occipital) horn being surrounded by three smaller, upwards divergent horns.

1. Lophocorys astrocephala, n. sp. (Pl. 69, fig. 9).

Shell smooth, inversely ovate, with deep collar and slight lumbar stricture. Length of the three joints = 3 : 7 : 6, breadth = 4 : 11 : 10. Cephalis subspherical, stellate, densely covered with numerous (ten to twenty or more) divergent, large, slenderly conical horns, the longest of which reach the length of the shell. Thorax campanulate, with small, regular, circular pores. Abdomen tapering towards the constricted mouth, in the upper half with the same pores, in the lower half with smaller, scarce pores, or nearly hyaline.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.06; breadth, a 0.04, b 0.11, c 0.1.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Lophocorys acanthocephala, Haeckel.

Eucyrtidium acanthocephalum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. ix. fig. 8.

Shell rough, bottle-shaped, with two slight strictures. Length of the three joints = 5 : 11 : 7, breadth = 4 : 12 : 10. Cephalis conical, with a large pyramidal horn of the same length, and three smaller divergent accessory horns at the base of the three edges of the latter. Thorax campanulate, nearly as long as the tapering abdomen (which in the figure of Ehrenberg is broken off). Pores regular, circular, quincuncial.

Dimensions.—Length of the three joints, a 0.05, b 0.11, c 0.07; breadth, a 0.04, b 0.12, c 0.1.

Habitat.—Fossil in Barbados.

3. Lophocorys bicornis, Haeckel.

Eucyrtidium bicorne, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 7.

Shell smooth, almost spindle-shaped, with two slight strictures. Length of the three joints = 2 : 8 : 3, breadth = 3 : 5 : 4. Cephalis hemispherical, with two stout, pyramidal, divergent horns of twice the length. Thorax ovate, with seven to eleven transverse rows of small, regular, circular pores (often very scarce in the upper half). Abdomen with two to four transverse rows of the same pores. Mouth constricted, half as broad as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.03; breadth, a 0.03, b 0.05, c 0.04.

Habitat.—Fossil in Barbados.

4. Lophocorys quadricornis, n. sp.

Shell rough, slenderly ovate, with two distinct strictures. Length of the three joints = 2 : 4 : 2, breadth = 2 : 4 : 3. Cephalis ovate, with four very stout, three-sided prismatic horns; the largest is as long as the thorax and vertical upon the apex, the three smaller are as long as the cephalis and diverge upwards from the base of the former. Thorax ovate, with large, irregular, roundish pores, which are three to four times as broad as the small, circular pores of the first and the third joint. Constricted mouth half as broad as the thorax.

Dimensions.—Length of the three joints, a 0.045, b 0.085, c 0.04; breadth, a 0.035, b 0.075, c 0.06.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

5. Lophocorys bovicornis, n. sp. (Pl. 69, fig. 12).

Shell rough, subovate, with two deep strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 3 : 4. Cephalis subspherical, with two divergent, curved horns of different lengths. Thorax campanulate, with small, circular pores. Abdomen subspherical, truncate at both poles, twice as broad as the constricted mouth, thorny, with very large, circular pores, four to six times as broad as those of the smaller thorax.

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.04, b 0.09, c 0.12.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

Genus 622. Theocampe,^[127] n. gen.

Definition.—Theocorida (vel Tricyrtida eradiata aperta) with ovate abdomen, broader than the constricted mouth. Cephalis without horn.

The genus Theocampe differs from the two preceding genera in the absence of horns on the cephalis, and may, therefore be derived from Theocorys by reduction of the apical horn. It bears to the latter the same relation as Tricolocampe does to Theocyrtis.

Subgenus 1. Theocampana, Haeckel.

Definition.—Pores of the thorax and the abdomen of nearly equal size and similar form.

1. Theocampe ehrenbergii, Haeckel.

Dictyomitra ehrenbergii, Zittel, 1876, Zeitschr. d. deutsch. geol. Gesellsch., p. 82, Taf ii. fig. 5.

Shell ovate, smooth. Length of the three joints = 2 : 3 : 13, breadth = 4 : 7 : 12. Cephalis hemispherical. Thorax truncate, conical. Abdomen inflated, nearly spherical, twice as broad as the constricted mouth. Pores of nearly equal size and form, small, regular, circular.

Dimensions.—Length of the three joints, a 0.014, b 0.018, c 0.076; breadth, a 0.023, b 0.044, c 0.073.

Habitat.—Fossil in the chalk of Northern Germany; Brunswick (Zittel).

2. Theocampe pirum, Haeckel.

Eucyrtidium pirum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. x. fig. 14. Eucyrtidium excellens, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 540, Taf. xxxiii. fig. 31.

Shell ovate, smooth. Length of the three joints = 3 : 5 : 15, breadth = 6 : 10 : 16. Cephalis hemispherical. Thorax truncate conical. Abdomen inflated, subspherical, three times as broad as the constricted mouth. Pores of nearly equal size, regular, circular in the thorax alternating, in the abdomen disposed in five to six transverse, widely distant rows.

Dimensions.—Length of the three joints, a 0.015, b 0.025 c 0.075; breadth, a 0.03, b 0.05, c 0.08.

Habitat.—Fossil in the Tertiary rocks of Barbados.

3. Theocampe stenostoma, n. sp. (Pl. 66, fig. 23).

Shell about ovate, smooth. Length of the three joints = 3 : 4 : 3, breadth = 6 : 8 : 9. Cephalis hemispherical, large. Thorax and abdomen short, barrel-shaped. Both strictures deep. Abdomen three times as broad as the constricted mouth. Pores of equal size, regular, circular, disposed in oblique rows.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.03; breadth, a 0.06, b 0.08, c 0.09.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

4. Theocampe nucula, Haeckel.

Eucyrtidium nucula, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 29, Taf. vii. fig. 19.

Shell nearly ovate, rough. Length of the three joints = 3 : 5 : 3, breadth = 4 : 7 : 6. Cephalis hemispherical, large. Thorax and abdomen inflated. Both strictures deep. Thorax broader than the short abdomen, and twice as broad as the constricted mouth. Pores of equal size, regular, circular, regularly disposed in transverse rows: three in the cephalis, six in the thorax, and three in the abdomen.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.03; breadth, a 0.04, b 0.07, c 0.06.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms; also fossil in Barbados.

5. Theocampe cryptoprora, Haeckel.

Eucyrtidium cryptoprora, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 14.

Shell ovate, thin-walled, smooth, without external strictures, but with two distinct internal annular septa. Length of the three joints = 2 : 7 : 4, breadth = 3 : 7 : 6. Cephalis, large, subspherical, hyaline; its lower half hidden in the upper part of the campanulate thorax. Mouth little constricted, nearly as broad as the truncate abdomen. All pores equal, small, regular, circular.

Dimensions.—Length of the three joints, a 0.025, b 0.07, c 0.04; breadth, a 0.03, b 0.07, c 0.06.

Habitat.—Tropical Pacific, Stations 225 to 265, in various depths.

6. Theocampe ovulum, n. sp.

Shell perfectly ovate, thick-walled, smooth, without external strictures, but with two broad, internal septa. Length of the three joints = 2 : 3 : 10, breadth = 3 : 6 : 8. Cephalis and thorax together obtuse, conical, with obliquely ascending pores. Abdomen inflated, twice as broad as the constricted mouth, with ten to twelve transverse rows of pores. All pores equal, small, regular, circular.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.1; breadth, a 0.03, b 0.06, c 0.08.

Habitat.—Fossil in Tertiary rocks of Barbados and Sicily.

7. Theocampe cassis, Haeckel.

Eucyrtidium cassis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 20.

Shell bottle-shaped, thin-walled, with slight collar, but deep lumbar stricture. Length of the three joints = 3 : 8 : 6, breadth = 2 : 7 : 7. Cephalis ovate. Thorax campanulate. Abdomen inflated, twice as broad as the constricted mouth. Pores equal, regular, circular, disposed in quincuncial rows.

Dimensions.—Length of the three joints, a 0.03, b 0.08. c 0.06; breadth, a 0.02, b 0.07, c 0.07.

Habitat.—Tropical Pacific (Philippines), Station 206, depth 2100 fathoms.

Subgenus 2. Theocamptra, Haeckel.

Definition.—Pores of the thorax and the abdomen of different sizes or dissimilar forms.

8. Theocampe sphærothorax, n. sp. (Pl. 66, fig. 25).

Shell almost ovate, rough. Length of the three joints = 2 : 5 : 10, breadth = 3 : 8 : 8. Cephalis hemispherical. Thorax nearly spherical, truncate. Abdomen ovate, twice as broad as the constricted mouth. Pores subregular, circular, quincuncially disposed, in the abdomen twice as broad as in the thorax, and four times as broad as in the cephalis.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.1; breadth, a 0.03, b 0.08, c 0.08.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

9. Theocampe versipellis, Haeckel.

Eucyrtidium versipellis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 14.

Shell slenderly ovate, rough. Length of the three joints = 3 : 5 : 13, breadth = 4 : 8 : 9. Cephalis subspherical, without pores. Thorax hemispherical. Abdomen inflated, twice as broad as the constricted mouth. Pores subregular, circular, quincuncially disposed, in the abdomen three times as broad as in the thorax.

Dimensions.—Length of the three joints, a 0.025, b 0.05, c 0.13; breadth, a 0.04, b 0.08, c 0.09.

Habitat.—Fossil in Barbados.

10. Theocampe megalopora, Haeckel.

Eucyrtidium megaloporum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 19.

Shell almost ovate, with two distinct strictures. Length of the three joints = 2 : 6 : 3, breadth = 3 : 6 : 4. Cephalis hemispherical. Thorax ovate, inflated. Abdomen inversely ovate, two to three times as broad as the constricted mouth. Pores subregular, circular, quincuncially disposed, twice as broad in the large thorax as in the smaller abdomen.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.03; breadth, a 0.03, b 0.06, c 0.04.

Habitat.—Central Pacific, Station 267, depth 2700 fathoms.

11. Theocampe collaris, n. sp. (Pl. 66, fig. 18).

Shell almost ovate, with two distinct strictures. Length of the three joints = 3 : 3 : 6, breadth = 4 : 5 : 7. Cephalis obtuse conical, with five or six transverse rows of small pores. Thorax truncate conical, with longitudinal furrows, each of which contains a single pore. Abdomen inflated, with five or six distant, transverse rows of small, circular pores.

Dimensions.—Length of the three joints, a 0.03, b 0.03, c 0.06; breadth, a 0.04, b 0.05, c 0.07.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

12. Theocampe gemmata, Haeckel.

Eucyrtidium gemmatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 6.

Shell slenderly ovate, smooth, with two internal annular septa. Length of the three joints = 1 : 1 : 4, breadth = 1 : 2 : 3. Cephalis campanulate, nearly as large as the truncate, conical thorax, both with small, irregular, obliquely descending pores. Abdomen broader, twice as broad as the constricted mouth, with numerous longitudinal ribs, alternating with single rows of small, circular pores. (This and the following allied species approach to Cycladophora, by the abdominal ribs.)

Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.07; breadth, a 0.025, b 0.035, c 0.045.

Habitat.—Fossil in Barbados.

13. Theocampe costata, n. sp. (Pl. 66, fig. 24).

Shell almost ovate, with two sharp strictures. Length of the three joints = 2 : 4 : 8, breadth = 3 : 5 : 7. Cephalis hemispherical. Thorax twice as large, also hemispherical, both with regular, circular, quincuncial pores. Abdomen broader, with numerous longitudinal ribs, alternating with longitudinal rows of larger pores. Mouth constricted, half as broad as the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.08; breadth, a 0.03, b 0.05, c 0.07.

Habitat.—Indian Ocean, Sunda Straits (Rabbe), surface.

14. Theocampe cryptocephala, Haeckel.

Eucyrtidium cryptocephalum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 11.

Shell ovate, rough, with two distinct strictures. Length of the three joints = 1 : 2 : 4, breadth = 1 : 4 : 5. Cephalis subspherical, its lower half hidden in the campanulate thorax. Abdomen subspherical, twice as broad as the constricted mouth. Pores subregular, circular, quincuncial, twice as broad in the abdomen as in the thorax.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.07; breadth, a 0.025, b 0.07, c 0.09.

Habitat.—Fossil in Barbados.

Subfamily 2. Theocapsida, Haeckel, 1881, Prodromus, p. 436.

Definition.—Theocyrtida with the basal mouth of the shell fenestrated (vel Tricyrtida eradiata clausa).

Genus 623. Theocapsa,^[128] Haeckel, 1881, Prodromus, p. 436.

Definition.—Theocapsida (vel Tricyrtida eradiata clausa), with an apical horn, and a terminal lattice-plate on the mouth.

The genus Theocapsa, and the two following genera, represent together the small subfamily of Theocapsida, or of those Tricyrtida in which the mouth is closed by a lattice-plate, and external radial appendages are wanting. Theocapsa may be derived from Theocorys by fenestration of the constricted mouth.

Subgenus 1. Theocapsetta, Haeckel.

Definition.—Thorax of about the same size as the abdomen, or somewhat larger; pores of both nearly equal in size and similar in form.

1. Theocapsa aristotelis, n. sp. (Pl. 66, fig. 6).

Shell subovate, smooth, with two distinct strictures. Length of the three joints = 2 : 6 : 7, breadth = 3 : 8 : 8. Cephalis hemispherical, with a conical, slender horn of about the same length. Thorax and abdomen nearly equal in size, thin-walled, smooth, with small, regular, circular pores of equal size. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.07; breadth, a 0.03, b 0.08, c 0.08.

Habitat.—Mediterranean (Gibraltar), Atlantic (Canary Islands), surface.

2. Theocapsa plinii, n. sp.

Shell subovate, smooth, with two indistinct strictures. Length of the three joints = 2 : 5 : 6, breadth = 3 : 7 : 7. Cephalis hemispherical, with a pyramidal, thick horn of about the same length. Thorax and abdomen of nearly equal size, thick-walled, rough, with large, regular, circular, double-edged pores of equal size (twice as large and half as numerous as in the similar preceding species).

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.06; breadth, a 0.03, b 0.07, c 0.07.

Habitat.—Central Pacific, Stations 265 to 268, depth 2700 to 2900 fathoms.

3. Theocapsa democriti, n. sp. (Pl. 66, fig. 8).

Shell slender, ovate, spiny, with two distinct strictures. Length of the three joints = 3 : 5 : 6, breadth = 4 : 7 : 7. Cephalis ovate, with numerous slender horns of the same length. Thorax and abdomen with small, irregular, roundish pores of nearly equal size, armed with scattered slender spines, half as long as the cephalic horns. Basal pole hemispherical, rounded.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.06; breadth, a 0.04, b 0.07, c 0.07.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

4. Theocapsa galeni, n. sp.

Shell broadly ovate, spiny, with two deep strictures. Length of the three joints = 2 : 7 : 6, breadth = 3 : 8 : 7. Cephalis hemispherical, with two conical, divergent horns of the same length. Thorax and abdomen with large, irregular, roundish pores of nearly equal size, armed with numerous short spines, not larger than the pores. Basal pole conical, pointed.

Dimensions.—Length of the three joints, a 0.02, b 0.07, c 0.06; breadth, a 0.03, b 0.08, c 0.07.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

Subgenus 2. Theocapsilla, Haeckel.

Definition.—Thorax of about the same size as the abdomen, or somewhat larger; pores of the two different in size or form.

5. Theocapsa wottonis, n. sp. (Pl. 66, fig. 11).

Shell subovate, rough, with two deep strictures. Length of the three joints = 3 : 7 : 5, breadth = 3 : 9 : 8. Cephalis subspherical, with regular, circular, hexagonally-framed pores, and with a stout pyramidal horn of the same length. Thorax conical, with subregular, circular, double-edged pores. Abdomen hemispherical, smaller and thinner walled, with irregular, somewhat oblong pores. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.03, b 0.07, c 0.05; breadth, a 0.03, b 0.09, c 0.08.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

6. Theocapsa gessneri, n. sp.

Shell broadly ovate, with two deep strictures. Length of the three joints = 3 : 9 : 5, breadth = 4 : 10 : 4. Cephalis hemispherical, with a slender, conical horn of the same length. Thorax subspherical, with small, regular, circular pores. Abdomen inversely conical, with few large, somewhat oblong pores. Basal pole acute.

Dimensions.—Length of the three joints, a 0.03, b 0.09, c 0.05; breadth, a 0.04, b 0.1, c 0.04.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

7. Theocapsa aldrovandi, n. sp.

Shell slender, inversely ovate, with two slight strictures. Length of the three joints = 3 : 8 : 14, breadth = 4 : 11 : 8. Cephalis subglobular, with a conical horn of the same length. Thorax also subglobular, papillate, with regular, circular, hexagonally-framed pores. Abdomen inversely conical, slender, with very small and numerous, subregular, circular pores. Basal pole ovate, pointed.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.14; breadth, a 0.04, b 0.11, c 0.08.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

8. Theocapsa malpighii, n. sp. (Pl. 66, fig. 15).

Shell inversely ovate, with two distinct strictures. Length of the three joints = 3 : 8 : 11, breadth = 4 : 9 : 8. Cephalis hemispherical, with a conical horn of the some length Thorax hemispherical, thorny, with very small circular pores, surrounded by large, regular, hexagonal frames. Abdomen inversely campanulate, with larger circular pores, and longitudinal ribs. Basal pole blunt, conical.

Dimensions.—Length of the three joints, a 0.03, b 0.08, c 0.11, breadth, a 0.04, b 0.09, c 0.08.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Subgenus 3. Theocapsomma, Haeckel.

Definition.—Thorax much smaller than the abdomen, pores of the two nearly equal in size and similar in form.

9. Theocapsa linnæi, n. sp. (Pl. 66, fig. 13).

Shell slender, subcylindrical, rough with two slight strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 4 : 4. Cephalis hemispherical, with a pyramidal horn of twice the length (sometimes, as in the specimen figured, one or two small accessory horns occur at its base). Thorax hemispherical, thick-walled. Abdomen nearly cylindrical, twice as long as the thorax, thin-walled, with a hemispherical, rounded basal pole. The specimen figured is an abnormal one, with some deformities on the irregular abdomen; in numerous other specimens the abdomen is cylindrical, regular. Pores of the thorax and abdomen equal, very small and numerous, regular, circular, three to four times as broad as the bars.

Dimensions.—Length of the three joints, a 0.02, b 0.05 to 0.06, c 0.1 to 0.12; breadth, a 0.03, b 0.06 to 0.07, c 0.07 to 0.08.

Habitat.—Cosmopolitan; Atlantic, Indian, and Pacific Oceans; many Stations at various depths.

10. Theocapsa forskalii, n. sp. (Pl. 66, fig. 9).

Shell slender, subcylindrical, smooth, with two slight strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 2. Cephalis hemispherical, with a conical horn of half the length. Abdomen three times as long as the thorax, of the same breadth, with the same irregular, roundish pores, large and small intermingled. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.09; breadth, a 0.03, b 0.06, c 0.06.

Habitat.—North Atlantic, Canary Islands, Station 353, depth 2965 fathoms.

11. Theocapsa wolffii, n. sp. (Pl. 66, fig. 14).

Shell slender, spindle-shaped very thick-walled, rough, without external strictures, but with two broad internal girdles. Length of the three joints = 2 : 3 : 15, breadth = 4 : 5 : 7. Cephalis with a short horn of the same length, conical. Abdomen five times as long as the thorax, with the same subregular, circular pores. Basal pole inversely conical, with some larger, elongate pores.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.15; breadth, a 0.04, b 0.05, c 0.07.

Habitat.—Mediterranean, Crete, depth 1620 fathoms (Spratt).

12. Theocapsa pallasii, n. sp.

Shell subovate, thorny, with two slight strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 3. Cephalis ovate, with a pyramidal horn of the same length. Thorax and abdomen with subregular, circular pores of medium size. Basal pole hemispherical. (Differs from Theocapsa mülleri, Pl. 66, fig. 7, mainly in the larger number and smaller size of the regular, quincuncial pores.)

Dimensions.—Length of the three joints, a 0.03, b 0.06, c 0.09; breadth, a 0.03, b 0.06, c 0.09.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms.

Subgenus 4. Theocapsura, Haeckel.

Definition.—Thorax much smaller than the abdomen, pores of the two different in size or form.

13. Theocapsa lamarckii, n. sp. (Pl. 66, fig. 16).

Shell slenderly ovate, rough, with two distinct strictures. Length of the three joints = 1 : 2 : 7, breadth = 1 : 4 : 5. Cephalis subspherical, with a conical horn of twice the length. Thorax conical, with regular, circular pores. Abdomen three times longer, with subregular, hexagonal pores of twice the size. Basal pole hemispherical, with very large, irregular, roundish pores.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.14; breadth, a 0.03, b 0.08, c 0.1.

Habitat.—Indian Ocean, Madagascar (Rabbe), surface.

14. Theocapsa cuvieri, n. sp. (Pl. 66, fig. 10).

Shell slenderly spindle-shaped, thorny, with two slight strictures. Length of the three joints = 1 : 3 : 6, breadth = 1 : 3 : 3. Cephalis subspherical, with a conical horn of the same length. Thorax conical, spiny, with regular, circular, double-edged pores. Abdomen thinner-walled, inversely conical, with irregular, roundish pores. Basal pole acute, with a bunch of larger spines.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.12; breadth, a 0.02, b 0.05, c 0.06.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

15. Theocapsa baerii, n. sp.

Shell slenderly spindle-shaped, smooth with two indistinct strictures. Length of the three joints = 1 : 2 : 8, breadth = 2 : 3 : 4. Cephalis hemispherical, with a thick conical horn of the same length. Abdomen four times as long as the thorax. Pores in the thorax small and numerous, regular, circular, in the abdomen twice as large, and irregularly roundish. Basal pole inversely conical, acute. (Differs from Theocapsa wolffii, Pl. 66, fig. 14, mainly in the shape of the pores.)

Dimensions.—Length of the three joints, a 0.015, b 0.03, c 0.12; breadth, a 0.03, b 0.04, c 0.06.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

16. Theocapsa rathkei, n. sp.

Shell slenderly conical, with two slight strictures. Length of the three joints = 1 : 2 : 10, breadth = 2 : 4 : 15. Cephalis small, with a large, conical horn of three times the length. Thorax small, thorny, with small irregular, roundish pores. Abdomen very large, as long and as broad as the thorax, with irregular polygonal or roundish, very large pores, the margin of which is finely denticulate. Basal pole truncate, rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.05, c 0.2; breadth, a 0.04, b 0.08, c 0.3.

Habitat.—Fossil in Barbados.

17. Theocapsa schwannii, n. sp.

Shell slenderly ovate, or pear-shaped, with two distinct strictures. Length of the three joints = 1 : 2 : 7, breadth = 2 : 4 : 7. Cephalis subspherical, small, with a stout, pyramidal horn of three times the length. Cavity of the thorax subspherical, its thick wall with small, regular, circular, hexagonally-framed pores. Abdomen very thick-walled, with crested bars, and very large, irregular, roundish pores. Basal pole rounded, truncate.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.14, breadth, a 0.04, b 0.08, c 0.14.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

18. Theocapsa mülleri, n. sp. (Pl. 66, fig. 7).

Shell slenderly ovate, or pear-shaped, spiny, with two indistinct strictures. Length of the three joints = 1 : 2 : 3, breadth = 1 : 2 : 3. Cephalis ovate, with a stout, pyramidal horn of the same length, and with a variable number of smaller accessory horns. Pores irregular, roundish, three to four times as broad in the inflated abdomen as in the thorax. Basal pole hemispherical, spiny.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.09; breadth, a 0.03, b 0.07, c 0.09.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

19. Theocapsa sarsii, n. sp.

Shell pear-shaped, with two indistinct strictures. Length of the three joints = 1 : 1 : 3, breadth = 1 : 2 : 4. Cephalis with a thick horn of the same length, conical. Abdomen subspherical, very thick-walled, its pores regular, circular, twice as broad as the bars, and three times as broad as those of the thorax. Basal pole flat, rounded.

Dimensions.—Length of the three joints, a 0.04, b 0.05, c 0.12; breadth, a 0.05, b 0.11, c 0.15.

Habitat.—Fossil in Barbados.

20. Theocapsa darwinii, n. sp. (Pl. 66, fig. 12).

Shell pear-shaped, with two distinct strictures. Length of three joints = 1 : 1 : 5, breadth = 1 : 2 : 5. Cephalis hemispherical, with a conical horn of twice the length. Thorax campanulate, with small, regular, circular pores. Abdomen broad, ovate, with larger, regular, circular, hexagonally-framed pores. Basal pole hemispherical.

Dimensions.—Length of the three joints, a 0.03, b 0.04, c 0.2; breadth, a 0.04, b 0.08, c 0.2.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

Genus 624. Tricolocapsa,^[129] Haeckel.

Definition.—Theocapsida (vel Tricyrtida eradiata clausa) without apical horn, with a terminal lattice-plate on the mouth.

The genus Tricolocapsa differs from the preceding Theocapsa in the loss of the apical horn, and exhibits therefore to it the same relation that Theocampe bears to Theocorys. In some species (Pl. 66, figs. 1, 3) a small tube begins to be developed on the cephalis, and these may perhaps be separated as a peculiar genus, Tricolopera.

Subgenus 1. Tricolocapsula, Haeckel.

Definition.—Thorax of about the same size as the abdomen, or larger.

1. Tricolocapsa theophrasti, n. sp. (Pl. 66, fig. 1).

Shell slenderly ovate, with two slight strictures. Length of the three joints = 2 : 8 : 5, breadth = 3 : 7 : 5. Cephalis hemispherical, with a larger, tube-like, cervical pore at the collar stricture. Thorax very thick-walled, with irregular, roundish, double edged pores, smaller than the bars between them. Abdomen smaller, inversely campanulate-conical, with very irregular pores. Basal pole acute.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.05; breadth, a 0.03, b 0.07, c 0.05.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Tricolocapsa dioscoridis, n. sp. (Pl. 66, fig. 3).

Shell short and broad, with two deep strictures. Length of the three joints = 3 : 5 : 4, breadth = 4 : 7 : 5. Cephalis hemispherical, with a larger, tube-like, cervical pore above the collar stricture. Thorax very broad, with irregular, large and spare, roundish pores. Abdomen much smaller, inversely conical, with smaller pores. Basal pole obtuse.

Dimensions.—Length of the three joints, a 0.03, b 0.05, c 0.04; breadth, a 0.04, b 0.07, c 0.05.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

3. Tricolocapsa linnæi, n. sp. (Pl. 66, fig. 5).

Shell short and broad, with two deep strictures. Length of the three joints = 1 : 4 : 2, breadth = 1 : 4 : 2. Cephalis hemispherical. Thorax thick-walled, inflated, with subregular, circular, double-edged pores. Abdomen much smaller, thin-walled, with irregular, polygonal pores. Basal pole hemispherical, rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.08, c 0.05; breadth, a 0.03, b 0.08, c 0.05.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

4. Tricolocapsa decandollei, n. sp. (Pl. 66, fig. 4).

Shell subovate, with two sharp strictures. Length of the three joints = 2 : 2 : 2, breadth = 3 : 4 : 3.5. Cephalis campanulate. Thorax broader, ring-shaped. Abdomen inversely hemispherical. All three joints of the same length, thick-walled, with the same regular and peculiar reticulation, the small circular pores being surrounded by square, elevated frames.

Dimensions.—Length of the three joints, a 0.07, b 0.07, c 0.07; breadth, a 0.10, b 0.14, c 0.12.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Subgenus 2. Tricolocapsium, Haeckel.

Definition.—Thorax much smaller than the abdomen.

5. Tricolocapsa brownii, n. sp.

Shell ovate, very thick-walled, with two indistinct strictures. Length of the three joints = 2 : 4 : 7, breadth = 3 : 7 : 10. Cephalis flat, hemispherical. Thorax truncate, conical. Abdomen inflated, inversely hemispherical. Pores regular, circular, of the same breadth as the bars, hexagonally-framed, twice as large in the abdomen as in the thorax. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.04, c 0.07; breadth, a 0.03, b 0.07, c 0.1.

Habitat.—Fossil in Barbados.

6. Tricolocapsa schleidenii, n. sp. (Pl. 66, fig. 2).

Shell subconical, with two deep strictures. Length of the three joints = 2 : 3 : 6, breadth = 3 : 5 : 6. Cephalis subspherical. Pores subregular, circular, arranged in transverse girdles, three in the broad thorax, six in the subglobular abdomen. Basal pole rounded.

Dimensions.—Length of the three joints, a 0.02, b 0.03, c 0.06; breadth, a 0.03, b 0.05, c 0.06.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

Genus 625. Phrenocodon,^[130] n. gen.

Definition.—Theocapsida (vel Tricyrtida eradiata clausa) with an apical horn, and a lattice-plate between thorax and abdomen.

The genus Phrenocodon differs from the two preceding genera in the remarkable circumstance, that the basal lattice-plate closes not the terminal mouth itself, but the constricted opening between thorax and abdomen. It may therefore be regarded as a Sethocapsa, which has developed a third, open, abdominal joint. The cephalis bears an apical horn.

1. Phrenocodon clathrostomium, n. sp. (Pl. 70, figs. 7, 8).

Shell campanulate-conical, with two deep strictures. Length of the three joints = 2 : 6 : 3, breadth = 3 : 10 : 14. Cephalis hemispherical, with an oblique curved horn of the same length. Thorax subconical, with polygonal, roundish pores, increasing in size towards the girdle. A perfect fenestrated diaphragm, with irregular, roundish pores of very different sizes, separates the thorax from the abdomen. The latter is composed of three parallel, circular rings, which are connected by fifteen to twenty radial beams. As the middle ring is larger than the two others, the beams between the large quadrangular pores are divergent in the upper, convergent in the lower girdle. Short prolongations of the divergent beams form a coronal around the middle ring (compare fig. 7 profile, fig. 8 from below).

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.03; breadth, a 0.03, b 0.1, c 0.14.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Phrenocodon diaphragma, n. sp.

Shell campanulate-conical, very similar to that of the preceding species, but with abdomen and proportions different. Length of the three joints = 1 : 3 : 2, breadth = 1 : 4 : 4. Abdomen cylindrical, with two or three transverse rows of large quadrangular meshes (fifteen to twenty in each row), without the characteristic inflexion of the preceding species, and without the coronal.

Dimensions.—Length of the three joints, a 0.02, b 0.06, c 0.034; breadth, a 0.02, b 0.08, c 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Section IV. STICHOCYRTIDA, Haeckel, 1862, Monogr. d. Radiol., p. 280, 312 (Pls. 75-80).

Stichocyrtida et Tetracyrtida, Haeckel, 1881, Prodromus, p. 437, 438.

Definition.—Cyrtoidea polythalamia, with annulated shell, divided by three to six or more transverse, horizontal constrictions, into four to seven or more annular joints. (The first joint represents the cephalis, the second the thorax, the third the abdomen, all the following joints together a post-abdomen.)

Synopsis of the three Families and six Subfamilies of Stichocyrtida.

Family LXVIII. Podocampida. Three radial apophyses.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth open,	Stichopilida.
		Mouth closed,	Stichoperida.
Family LXIX. Phormocampida. Numerous radial apophyses.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth open,	Stichophormida.
		Mouth closed,	Stichophænida.
Family LXX. Lithocampida. No radial apophyses.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mouth open,	Stichocorida.
		Mouth closed,	Stichocapsida.

Family LXVIII. Podocampida, n. fam.

Artopilida et Artoperida, Stichopilida et Stichoperida, Haeckel, 1881, Prodromus, p. 437-439.

Definition.—Stichocyrtida triradiata. (Cyrtoidea with an annulated shell, divided by three or more transverse constrictions into four or more annular joints, and bearing three radial apophyses).

The family Podocampida comprises those Cyrtoidea in which the lattice-shell is composed of numerous (four to eight or more) annular joints, and bears three external radial apophyses. It may be divided into two subfamilies, differing in the shape of the terminal mouth. This is a simple wide opening in the Stichopilida (and the united Artopilida), closed by a lattice-plate in the Stichoperida (and the united Artoperida). The phylogenetic origin of the Podocampida may be found in the Podocyrtida (p. 1314).

Very few forms only of the Podocampida were hitherto known, viz., Stichopilium (Pterocodon) davisianum, and three fossil species from Barbados, figured by Ehrenberg; Artopera loxia (united by him with Lithornithium), and two species of Pteropilium (sphinx and bombus, both united by him with the three-jointed Pterocanium). In general, the triradiate Stichocyrtida are much rarer and much poorer in specific forms than the triradiate Tricyrtida, their ancestors. We have observed altogether only forty-four species, thirty Stichopilida, and fourteen Stichoperida; the former are disposed among seven, the latter among three genera.

The three radial apophyses appear either as lateral ribs or prominent wings in the thorax (Pl. 77, fig. 8-12), or as three terminal feet around the mouth (Pl. 97, fig. 15). Sometimes the ribs are replaced by three radial combs, or rows of spines, and these may be united by three divergent beams, forming three vaulted bridges with numerous bows (Pl. 75, figs. 10, 11). The lateral wings or ribs, as well as the terminal feet, are either solid or fenestrated.

Synopsis of the Genera of Podocampida.

I. Subfamily Stichopilida. Mouth of the terminal joint a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Three lateral appendices or wings (no terminal feet).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Lateral wings are solid spines.		Cephalis with horn,	626. Stichopilium.
				Lateral wings are latticed.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	With horn,	627. Artopilium.
						Without horn,	628. Pteropilium.
		Three terminal appendices or feet at the peristome (all with cephalic horn).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Three lateral ribs or crests prolonged into the three terminal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Feet solid,	629. Stichocampe.
						Feet latticed,	630. Stichopterium.
				No lateral ribs. Three terminal feet free.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Feet solid,	631. Podocampe.
						Feet latticed,	632. Stichopodium.
II. Subfamily Stichoperida. Mouth of the terminal joint closed by a lattice-plate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Last joint rounded, without a vertical basal spine (cephalis with horn).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Three lateral solid ribs (or rows of spines),			633. Stichopera.
				Three lateral latticed wings (or rows of wings),			634. Cyrtopera.
		Last joint conical, pointed, with a vertical basal spine.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Three lateral solid ribs (cephalis with an apical horn),			635. Artopera.

Subfamily 1. Stichopilida, Haeckel, 1881, Prodromus, p. 439.

Definition.—Podocampida with the terminal mouth of the shell open (vel Stichocyrtida triradiata aperta).

Genus 626. Stichopilium,^[131] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta) with three solid lateral ribs or wings, without terminal feet. Cephalis with a horn.

The genus Stichopilium is the most primitive among all Stichocyrtida, and represents perhaps the common ancestral form of this family. The shell is composed of four or more joints (sometimes ten to twelve), has a wide open terminal mouth, and three lateral solid wings or ribs (sometimes a little latticed on the base). Stichopilium may be derived from Theopilium or Pterocorys by addition of new terminal joints.

Subgenus 1. Triacartus, Haeckel, 1881, Prodromus, p. 437.

Definition.—Shell with three annular strictures, and four distinct joints.

1. Stichopilium cortina, n. sp.

Shell ovate, with three sharp strictures. Length of the four joints = 2 : 6 : 3 : 4. Cephalis subspherical, with a slender pyramidal horn of twice the length. The three edges of the horn are prolonged into three strong divergent ribs, along the three first joints, and into three free conical lateral spines, directed downwards, on the end of the third joint. The fourth joint is subcylindrical; its circular, terminal mouth half as broad as the third joint, which is the broadest. Pores small, regular, hexagonal, with thin bars.

Dimensions.—Length of the shell (with four joints) 0.15, breadth 0.08. Length of the single joints, a 0.02, b 0.06, c 0.03, d 0.04.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Stichopilium costatum, n. sp.

Shell conical, or nearly pyramidal, with three distinct strictures. Length of the four joints = 3 : 5 : 8 : 4. Cephalis subconical, with a stout pyramidal horn of the same length. Thorax campanulate, with six longitudinal ribs, from three of which in the middle arise three horizontal, conical, free spines or wings, about as long as the cephalis. The third large prismatic joint bears twelve parallel ribs, six new ribs being intercalated between the six former. Fourth joint short, cylindrical, without ribs, the wide open mouth not constricted, nearly as broad as the third joint, which is the broadest. Pores small, irregular, polygonal, or roundish.

Dimensions.—Length of the shell (with four joints) 0.2, breadth 0.12. Length of the single joints, a 0.03, b 0.05, c 0.08, d 0.04.

Habitat.—North Pacific, Station 244 (off Japan), depth 2900 fathoms.

3. Stichopilium bicorne, n. sp. (Pl. 77, fig. 9).

Shell conical, with three slight strictures. Length of the four joints = 4 : 14 : 5 : 3. Cephalis large, conical, with two stout pyramidal, divergent horns of twice the length. From its base (in the middle of the collar stricture) arise three internal, downwardly divergent ribs, which are prolonged on the outside of the upper half of the thorax into three stout, pyramidal, lateral spines (similar to the horns). The fourth joint, with wide open mouth, was the broadest, but not fully developed in the single specimen observed. Pores subregular, hexagonal, with thin bars.

Dimensions.—Length of the shell (with four joints) 0.02, breadth 0.09. Length of the single joints, a 0.02, b 0.07, c 0.025, d 0.015.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

4. Stichopilium davisianum, Haeckel.

Pterocodon davisianus, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 298, Taf. ii. fig. 10.

Cycladophora davisiana, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 289, Taf. ii. fig. 11.

Eucyrtidium davisianum, Haeckel, 1862, Monogr. d. Radiol., p. 328.

Pterocanium davisianum, Haeckel, 1862, Monogr. d. Radiol., p. 332.

Shell campanulate, conical, with three slight strictures. Length of the four joints = 2 : 3 : 4 : 3. Cephalis hemispherical, with few small pores and a short conical horn. Thorax campanulate, with larger circular pores, and three recurved, divergent, lateral wings of the same length. Third and fourth joints each with three transverse rows of very large hexagonal pores. The similar form described by Ehrenberg as Cycladophora davisiana, is either a mutilated specimen, or belongs to Lithostrobus.

Dimensions.—Length of the shell (with four joints) 0.12, breadth 0.08. Length of the single joints, a 0.02, b 0.03, c 0.04, d 0.03.

Habitat.—North Atlantic, Greenland, depth 1000 to 1500 fathoms.

5. Stichopilium campanulatum, n. sp. (Pl. 77, fig. 11).

Shell campanulate, with three slight strictures. Length of the four joints = 3 : 5 : 5 : 4. Cephalis subovate, with an internal rod-cross, and a stout pyramidal horn of the same length. From the middle of the collar stricture arise three divergent collar beams, which descend in the upper half of the campanulate thorax as three divergent ribs, and are prolonged into three free horizontal spines. (In the specimen figured these three wings are very short; in another specimen, found afterwards, there were three solid, pyramidal, horizontal spines, as long as the cephalic horn.) The third joint is the broadest, of about the same length as the fourth. (The annular septum between the two latter is by a mistake not figured). Pores subregular, circular, hexagonally framed.

Dimensions.—Length of the shell (with four joints) 0.17, breadth 0.12. Length of the single joints, a 0.03, b 0.05, c 0.05, d 0.04.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

6. Stichopilium triserratum, n. sp.

Shell slenderly campanulate, with three deep strictures. Length of the four joints = 2 : 4 : 6 : 3. Cephalis hemispherical, with a stout pyramidal horn three times the length. The three edges of the horn are prolonged into three strong prominent ribs along the three first joints; each rib bears a series of stout, irregular, triangular teeth. The fourth joint is without ribs; its constricted mouth is half as broad as the third (broadest) joint. Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.15, breadth 0.08. Length of the single joints, a 0.02, b 0.04, c 0.06, d 0.03.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Subgenus 2. Stichopilidium, Haeckel.

Definition.—Shell with four or more annular strictures and five or more joints.

7. Stichopilium macropterum, Haeckel.

Rhopalocanium varietas, Bury, 1862, Polycystins of Barbados, pl. xvii. fig. 7.

Shell slenderly conical, with five deep strictures. Length of the six joints = 2 : 5 : 4 : 3 : 3 : 6. Cephalis hemispherical, with a stout conical horn of twice the length. Thorax campanulate, with three large, triangular, widely divergent wings or ribbed solid spines, nearly as long as the shell. The breadth of the joints increases gradually; the last joint is the broadest, with wide open mouth. Pores subregular, circular.

Dimensions.—Length of the shell (with six joints) 0.23, breadth 0.1. Length of the single joints, a 0.02, b 0.05, c 0.04, d 0.03, e 0.03, f 0.06.

Habitat.—Fossil in Barbados.

8. Stichopilium pectinatum, n. sp.

Shell slenderly conical, with nine sharp strictures. All ten joints have nearly equal length, and increase gradually in breadth; the last joint is the broadest, and twice as long as each of the others, with wide open mouth. Cephalis subspherical, with a conical horn of the same length. Each joint (excepting the first and the last) bears three lateral, nearly horizontal spines, and the bases of all the spines are connected by three longitudinal, divergent ribs. Pores subregular, hexagonal. (Similar to Stichopera pectinata, Pl. 75, fig. 11.)

Dimensions.—Length of the shell (with ten joints) 0.32, breadth 0.1.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

9. Stichopilium thoracopterum, n. sp.

Shell slenderly ovate, twice as long as broad, with eleven slight annular strictures. The twelve joints (excepting the second) are of nearly equal length, or alternately longer and shorter. The eighth joint is the broadest, one and a half times as broad as the slightly constricted mouth. Cephalis small, hemispherical, with a pyramidal horn of twice the length. Thorax (or second joint) campanulate, twice to three times as long as each of the eleven other joints, with three longitudinal ribs, prolonged into three divergent, slender, free spines. Pores small, regular, hexagonal.

Dimensions.—Length of the shell (with twelve joints) 0.22, breadth 0.11. Length of each joint (on an average) 0.015 to 0.017, thorax 0.035.

Habitat.—South Pacific, Station 296, depth 1825 fathoms.

Genus 627. Artopilium,^[132] Haeckel, 1881, Prodromus, p. 437.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta) with three latticed lateral ribs or wings, without terminal feet. Cephalis with a horn.

The genus Artopilium (including also the genera Trictenartus, Pterocorythium, Stichopterygium, and Clathropyrgus of my Prodromus) has a shell of the same form as the preceding Stichopilium, but it differs in the fenestration of the three lateral ribs or wings, which in the latter are solid. The limit between the two genera is often not sharp. Artopilium may be also derived from the three-jointed Dictyoceras by addition of new terminal joints.

Subgenus 1. Trictenartus, Haeckel, 1881, Prodromus, p. 437.

Definition.—Shell with three annular strictures and four joints.

1. Artopilium elegans, n. sp. (Pl. 75, fig. 1).

Shell three-sided pyramidal, with three annular strictures. Length of the four joints = 1 : 2 : 9 : 3. Cephalis small, hemispherical, with two large, prismatic, divergent horns of three times the length. The three prominent edges of the second and third joints are finely latticed and dentated, and at the basal end of the third joint are prolonged into three stout, free, pointed, pyramidal, divergent wings, about as long as the horns. The fourth joint is only as long as the second, three-sided prismatic, its wide triangular mouth is armed with six parallel, vertical, slender teeth (two between every three wings). Network very delicate and regular, in the first and second joints with circular, in the third and fourth joints with small hexagonal meshes.

Dimensions.—Length of the shell (with four joints) 0.3, breadth of the third joint 0.3, of the fourth 0.2. Length of the single joints, a 0.02, b 0.04, c 0.18, d 0.06.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

2. Artopilium longicorne, n. sp. (Pl. 77, fig. 10).

Shell subovate, with three internal annular septa. Length of the four joints = 2 : 3 : 2 : 6. Cephalis hemispherical, with a very large three-sided prismatic horn, nearly as long as the shell. Along the three following joints arise three broad, triangular, latticed wings, about as long as the shell. The fourth joint is the broadest, and twice as broad as the constricted mouth. Pores in the two upper joints regular, circular, in the two lower and the three wings hexagonal.

Dimensions.—Length of the shell (with four joints) 0.13, breadth 0.09. Length of the single joints, a 0.02, b 0.03, c 0.02, d 0.06.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

3. Artopilium cyrtopterum, n. sp. (Pl. 77, fig. 12).

Shell subovate, with three sharp strictures. Length of the four joints = 1 : 2 : 3 : 3. Cephalis subspherical, with a stout, pyramidal horn of twice the length. Along the second and third joints arise three broad, triangular, latticed wings, about half as long as the shell. The third joint is the broadest, and twice as broad as the constricted mouth. Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.1. Length of the single joints, a 0.02, b 0.04, c 0.06, d 0.06.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

Subgenus 2. Clathropyrgus, Haeckel, 1881, Prodromus, p. 439.

Definition.—Shell with four or more annular strictures, and five or more joints.

4. Artopilium trifenestra, n. sp. (Pl. 75, fig. 7).

Clathropyrgus trifenestra, Haeckel, 1881, Prodromus et Atlas (loc. cit.).

Shell tower-shaped, nearly cylindrical, with nine deep strictures. The ten joints are of different lengths and breadths. The third and fourth joints are the longest, twice as long as the first, fifth, sixth, eighth, and ninth joints. The third, seventh, and tenth joints are the broadest, and nearly twice as broad as the second and ninth joints. The mouth of the last joint is dilated. The second joint bears three divergent ribs, and the third joint (as prolongations of these) three broad, triangular, lattice-wings, and between the latter three large, ovate openings or windows, recalling those in Clathrocanium (Pl. 64). Cephalis subspherical, with a pyramidal horn of twice the length. Pores subregular, circular, hexagonally framed.

Dimensions.—Length of the shell (with ten joints) 0.28, of the first and ninth joints 0.02, of the third and fourth joints 0.04; breadth of the third and seventh joints 0.08, of the second and ninth joints 0.04.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

5. Artopilium trigonopterum, n. sp.

Shell in the upper half campanulate-conical, in the lower half cylindrical, with seven internal septa. The four middle joints are equal in length, each about twice as long as each of the two first and of the two last joints. Cephalis hemispherical, with a conical horn of the same length. Along the first three joints arise three broad, triangular, lattice-wings. Pores small, regular, hexagonal, in the wings and the two first joints circular. The five lower joints are of equal breadth.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1. Length of the four middle joints, each about 0.034, of the two first and the two last, each 0.017.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

6. Artopilium cornutella, n. sp.

Shell slenderly conical, without external strictures, but with twelve to fifteen internal annular septa. All thirteen to sixteen joints are nearly equal or slightly different in length, but increase gradually in breadth. Along the whole shell arise three narrow, divergent lattice-wings, increasing in height towards the wide open mouth. Pores subregular, square, in three to four transverse rows on each joint, half as large in the three wings as in the joints. Cephalis small, subspherical, with a conical horn of twice the length. (In the specimen described the axis of the slender cone was straight, in another incomplete specimen curved; this may perhaps be a separate species, Artopilium curvatum.)

Dimensions.—Length of the shell (with sixteen joints) 0.3, basal breadth 0.12. Length of each single joint (on an average), 0.02.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

7. Artopilium stichopterygium, n. sp. (Pl. 75, fig. 8).

Stichopterygium tanypterum, Haeckel, 1881, Prodromus, p. 439, et Atlas.

Shell slenderly ovate, subconical, with five deep strictures. The four lower joints are nearly equal in length, each about twice as long as each of the first two joints. The fourth and fifth joints are the broadest. Along the whole shell arise three broad, triangular wings, which envelop the long, slender, pyramidal horn of the cephalis. In the delicate and loose lattice-work of each wing is a longitudinal series of six large, ovate apertures, one on each joint. The small pores of the shell are irregular, polygonal, or roundish.

Dimensions.—Length of the shell (with six joints) 0.17, breadth 0.08. Length of each of the four lower joints 0.03, of each of the two upper joints 0.015.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

8. Artopilium anomalum, Haeckel.

Eucyrtidium anomalum, Haeckel, 1862, Monogr. d. Radiol., p. 323, Taf. vii. figs. 11-13.

Lithocampe anomala, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 839.

Stichopterygium anomalum, Haeckel, 1881, Prodromus, p. 439.

Shell five-jointed, with four internal septa, of a peculiar, irregular, and abnormal form. Cephalis small, hemispherical, with an oblique, curved horn. Thorax inflated, campanulate, with three large, latticed, and carinated protuberances. The third joint (the first abdominal joint) nearly as large as the thorax, two to three times as long as the two last joints, the septa of which are connected in a peculiar manner by a common nodal point on one side. Pores subregular, circular. (Compare the detailed description of this remarkable species—perhaps the type of a peculiar genus, Stichopterygium—in my Monograph, loc. cit.)

Dimensions.—Length of the shell (with five joints) 0.15, breadth 0.1.

Habitat.—Mediterranean (Messina), surface.

Genus 628. Pteropilium,^[133] n. gen.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta) with three latticed external ribs or wings, without terminal feet. No horn upon the cephalis.

The genus Pteropilium (confounded by Ehrenberg with Pterocanium) differs from this three-jointed form by addition of new terminal joints. The shell-form is in general the same as in the preceding species, from which it may be derived by phylogenetic loss of the cephalic horn.

1. Pteropilium sphinx, Haeckel.

Pterocanium sphinx, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 255, Taf. xvii. fig. 5.

Shell slenderly conical, with three slight strictures. Each of the two last joints as long as the two first joints together. Cephalis hemispherical. Third joint with three prominent, divergent ribs, which are prolonged along the fourth joint into three latticed, triangular wings, ending in a free, strong, conical spine. Pores subregular, circular, twice as broad in the fourth joint as in the third, and three times as broad as in the second joint.

Dimensions.—Length of the shell (with four joints) 0.15, of the single joints, a 0.02, b 0.03, c 0.05, d 0.05; breadth of the third joint 0.09, of the fourth joint 0.06.

Habitat.—Fossil in Barbados.

2. Pteropilium bombus, Haeckel.

Pterocanium bombus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 82, Taf. xvii. fig. 4.

Shell broadly conical, with three deep strictures. Length and breadth of the four joints, gradually increasing giving the proportion 2 : 4 : 5 : 6. Cephalis hemispherical, second joint with three prominent ribs, which are prolonged along the third and fourth joints into three slender, triangular pointed wings, with few pores at the base. Pores of the shell subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.17, of the single joints, a 0.02, b 0.04, c 0.05, d 0.06; basal breadth 0.11.

Habitat.—Fossil in Barbados.

3. Pteropilium pyramis, n. sp.

Shell three-sided, pyramidal, with five deep strictures. Length and breadth of the six joints gradually increasing towards the wide mouth. Cephalis subconical. Along the four first joints arise three slender, divergent ribs, which at the fifth joint become three free, triangular, latticed wings, with long, descending, terminal spines. The sixth joint is free, without wings. Pores irregular, roundish.

Dimensions.—Length of the shell (with six joints) 0.2, basal breadth 0.2.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Genus 629. Stichocampe,^[134] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta) with three solid lateral ribs or wings, which are prolonged into three solid terminal feet. Cephalis with a horn.

The genus Stichocampe, together with the three following genera, represent a peculiar small group among the Stichocyrtida, differing from all other members of this family in the possession of three free terminal feet around the open mouth. In the two genera, Stichocampe and Stichopterium, these three feet are the terminal prolongations of three lateral ribs or crests, while in the two genera developed later, Podocampe and Stichopodium, the three original ribs are lost, and only the three free feet remain. Stichocampe (the most primitive of these four genera) may be derived from Theopodium by addition of new joints.

1. Stichocampe divergens, n. sp.

Shell spiny, broadly pyramidal, with six deep strictures. Seven joints gradually increasing in breadth and length, the seventh twice as broad as the fourth. Pores subregular, circular, hexagonally framed. The prominent edges of the pyramis are prolonged over the wide mouth into three slender, straight, divergent feet, half as long as the shell.

Dimensions.—Length of the shell (with seven joints) 0.3, of the last joint 0.06, of the fourth 0.03; breadth 0.25.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Stichocampe convergens, n. sp.

Shell smooth, slenderly pyramidal, with eight distinct strictures. All nine joints nearly equal in length. Pores regular, circular, forming three or four transverse rows in each joint. The smooth edges of the pyramis are prolonged over the wide mouth into three slender, slightly curved, and convergent feet, twice as long as one joint.

Dimensions.—Length of the shell (with nine joints) 0.25, of each joint, about 0.035; breadth 0.11.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

Genus 630. Stichopterium,^[135] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta), with three lateral ribs or wings, which are prolonged into three latticed, terminal feet. Cephalis with a horn.

The genus Stichopterium has in general the same shell-formation as the nearly allied Stichocampe, but differs from this ancestral form in the fenestration of the three terminal feet. It corresponds, therefore, to Pterocanium among the Tricyrtida.

1. Stichopterium pterocanium, n. sp.

Shell campanulate, with three distinct strictures. Length of the four joints = 2 : 3 : 4 : 3. Cephalis subspherical, with a conical horn of twice the length. Pores regular, hexagonal, with thin bars. From the collar stricture arise three divergent ribs, which in the fourth joint become latticed and prolonged over its mouth into three slender, pyramidal, latticed, divergent feet, nearly as long as the shell. (Similar to Pterocanium bicorne, Pl. 73, fig. 5, but with four distinct strictures.)

Dimensions.—Length of the shell (with four joints) 0.12, breadth 0.1. Length of the single joints, a 0.02, b 0.03, c 0.04, d 0.03.

Habitat.—South Pacific (off Patagonia), Station 304, surface.

2. Stichopterium virgineum, n. sp.

Shell three-sided, pyramidal, with four sharp strictures. Length of the five joints = 1 : 4 : 3 : 2 : 1. Cephalis hemispherical, with a pyramidal horn three times the length. Pores subregular, circular, in the second campanulate joint twice or three times as broad as in the four other joints. From the base of the cephalic horn arise three divergent ribs, which descend over the whole shell, and in the fourth joint become latticed and prolonged over the wide mouth of the fifth joint into three latticed, pyramidal feet, as long as the second joint. (Similar in general form to Pterocanium virgineum, Pl. 73, fig. 6.)

Dimensions.—Length of the shell (with five joints) 0.22, breadth 0.16. Length of the single joints, a 0.02, b 0.08, c 0.06, d 0.04, e 0.02.

Habitat.—Central Pacific, Station 281, surface.

3. Stichopterium dictyopodium, n. sp.

Shell subovate, with five internal annular septa. The third and the fourth joints are about twice as long as the two first and the two last joints. The fifth joint is the broadest. Pores small and numerous, regular, circular. The three first joints are without ribs. From the third stricture arise three divergent, triangular, latticed wings, which descend along the three last joints, and are prolonged over the wide mouth as three slender, fenestrated, divergent feet, two-thirds as long as the shell.

Dimensions.—Length of the shell (with six joints) 0.18, breadth 0.12. Length of the two middle joints 0.04, of the four others 0.02 to 0.03.

Habitat.—South Pacific, Station 288, surface.

Genus 631. Podocampe,^[136] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta), without lateral ribs or wings, but with three free, solid, terminal feet. Cephalis with a horn.

The genus Podocampe is next allied to Stichocampe, and has also three solid, free feet around the mouth, but it has lost the three lateral ribs of the latter. It corresponds to Podocyrtis among the Tricyrtida, and may be derived from this by addition of new terminal joints.

1. Podocampe tripodiscus, n. sp.

Shell ovate, with three annular septa. The fourth joint is the broadest, and as long as the three other joints together. Cephalis hemispherical, with a pyramidal horn of twice the length. Mouth constricted, with three convergent, curved, triangular feet, half as long as the last joint. Pores subregular, circular. (Similar to Podocyrtis pedicellaria, Pl. 72, fig. 8, but larger, with more slender feet, and four joints instead of three.)

Dimensions.—Length of the shell (with four joints) 0.2, of the last joint 0.1; breadth 0.12.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Podocampe trictenota, n. sp. (Pl. 97, fig. 15).

Shell slenderly ovate, nearly spindle-shaped, with three annular septa. The third joint is the broadest, somewhat longer than the second and third joints, and three times as long as the hemispherical cephalis, which bears a strong pyramidal horn of twice the length. Along the two first joints arise three divergent, dentate crests, each with four to six strong pyramidal teeth. Mouth strongly constricted, only as broad as the cephalis, with three conical, vertical, parallel feet, as long as the cephalis. Pores regular, circular, hexagonally framed.

Dimensions.—Length of the shell (with four joints) 0.14, of the third joint 0.06, of the last 0.04; breadth 0.08.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. Podocampe conica, n. sp.

Shell conical, with five distinct strictures. Six joints gradually increasing in length and breadth. The sixth joint is the broadest, and twice as long as the fifth joint, three times as long as the fourth. Cephalis conical, with a stout, conical horn of the same length. Mouth little constricted, with three divergent, conical feet, half as long as the shell. Pores subregular, circular. (Similar to Podocyrtis lithoconus, Pl. 72, fig. 3, but with six joints instead of three, and with divergent, slender feet.)

Dimensions.—Length of the shell (with six joints) 0.18, of the last joint 0.06; breadth 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

4. Podocampe cornuta, n. sp.

Shell slenderly conical, with seven distinct strictures. Eight joints of nearly equal length, gradually increasing in breadth. Along the three last joints arise three prominent crests, which are prolonged over the wide mouth into three divergent, conical feet, half as long as the shell. Cephalis hemispherical, with a conical, slender, curved horn, three times the length. Pores subregular, hexagonal.

Dimensions.—Length of the shell (with eight joints) 0.16, of each single joint (on an average) 0.02; basal breadth 0.07.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Genus 632. Stichopodium,^[137] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichopilida (vel Stichocyrtida triradiata aperta) without lateral ribs or wings, but with three free latticed terminal feet. Cephalis with a horn.

The genus Stichopodium differs from the preceding genus Podocampe in the fenestration of the three free terminal feet. It agrees in this character with the genus Stichopterium, and may be derived either from this by loss of the lateral ribs, or from the three-jointed Pterocanium by addition of new shell-joints.

1. Stichopodium dictyopodium, n. sp. (Pl. 75, fig. 6).

Shell subcylindrical, in the upper third conical, with six or seven internal annular septa. All seven or eight joints are about equal in length, except the small hemispherical cephalis, which is scarcely half as long, and bears an oblique, conical horn of the same length. Pores small and numerous, regular, circular, quincuncial. The last joint with wide open mouth, and a peristome of three large, triangular, latticed, shovel-shaped, vertical feet.

Dimensions.—Length of the shell (with seven joints) 0.2, breadth 0.11. Length of each single joint about 0.03, of the feet 0.03.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Subfamily 2. Stichoperida, Haeckel, Prodromus, p. 439.

Definition.—Podocampida with the terminal mouth of the shell fenestrated (vel Stichocyrtida triradiata clausa).

Genus 633. Stichopera,^[138] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichoperida (vel Stichocyrtida triradiata clausa) with three solid lateral ribs, or three longitudinal combs of spines. Cephalis with a horn.

The genus Stichopera, and the two following genera, represent the small subfamily of Stichoperida, or those triradiate Stichocyrtida in which the terminal mouth is closed by lattice-work. In Stichopera the three radial appendages are either solid lateral ribs or longitudinal combs of spines; the closed basal part of the shell is rounded, not pointed. It may be derived either from Stichopilium by closure of the mouth, or from Lithornithium by increase of the number of the joints.

Subgenus 1. Stichoperina, Haeckel.

Definition.—Shell with three solid radial ribs, or longitudinal dentate crests.

1. Stichopera ovata, n. sp.

Shell ovate, with three distinct strictures. Length of the four joints = 2 : 3 : 4 : 6. The fourth joint is the broadest, and twice as long as the second, with hemispherical basal pole. Cephalis hemispherical, with a conical horn of twice the length. Along the second and third joints descend three prominent divergent ribs, which disappear in the middle zone of the fourth joint. Pores regular, circular.

Dimensions.—Length of the shell (with four joints) 0.15, breadth 0.1. Length of the single joint, a 0.02, b 0.03, c 0.04, d 0.06.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Stichopera lagena, n. sp.

Shell bottle-shaped, with six sharp strictures; the upper half is slender, conical, and composed of six joints of nearly equal length, the lower half is formed only by the last subspherical joint. Cephalis subspherical, with a pyramidal horn of the same length. From its base arise three divergent ribs, which attain the greatest height in the fourth joint, and disappear in the sixth joint. (Similar to Stichophæna ritteriana, Pl. 75, fig. 12, but only with three ribs and seven joints.) Pores regular, hexagonal.

Dimensions.—Length of the shell (with seven joints) 0.25. Length of each joint 0.02 to 0.025, of the last joint 0.12; breadth 0.14.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Stichopera serrata, n. sp.

Shell bottle-shaped, with eight deep strictures. The first eight joints are little different in length, and form together a slender cone, while the last joint is four times as long (half as long as this cone), and subspherical. Cephalis conical, with a slender, prismatic horn of three times the length. Along the whole shell arise three divergent, serrate ribs, which disappear towards the hemispherical, basal pole. Pores subregular, hexagonal.

Dimensions.—Length of the shell (with nine joints) 0.21, breadth 0.08; length of each joint 0.016 to 0.019, of the last joint 0.07.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

Subgenus 2. Sticholagena, Haeckel.

Definition.—Shell with three radial combs or longitudinal rows of isolated spines (instead of the three radial ribs).

4. Stichopera pectinata, n. sp. (Pl. 75, fig. 11).

Shell club-shaped, with nine sharp strictures. The nine upper joints increase gradually in length and breadth, and are together three times as long as the inflated, inversely campanulate and rounded last joint. Each joint (excepting the first and the last) bears three thin, bristle-shaped spines, which are directed obliquely upwards. Cephalis subspherical, with a slender, conical horn of twice the length. Pores subregular, in the upper half circular, in the lower hexagonal.

Dimensions.—Length of the shell (with ten joints) 0.22, breadth 0.09; length of the eighth and ninth joints 0.02, of the last joint 0.075.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

5. Stichopera clavata, n. sp.

Shell club-shaped, with eight sharp strictures, very similar in form and structure to that of the preceding species, but differing from it in the club-like form of the inflated last joint, which is nearly half as long as the shell; its lower half is broader than the upper (the reverse being the case in the preceding species). The lateral spines of the three combs are not directed upwards, but downwards. Cephalis with a curved, conical horn of the same length.

Dimensions.—Length of the shell (with nine joints) 0.2, breadth 0.08; length of the eighth joint 0.02, of the last joint 0.09.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

6. Stichopera verticillata, n. sp.

Shell club-shaped, with ten sharp strictures, similar in form and structure to that of the two preceding species, but differing from them in the ovate form of the slender last joint, which is one-third as long as the whole shell, and five times as long as the preceding joint. The lateral spines of the three combs are directed nearly horizontally, and are much more numerous, each joint (excepting the first and last) bears six to twelve spines (two, three, or four in each radius). They form together about thirty horizontal verticils, each with three spines. Cephalis with a curved, conical horn of three times the length.

Dimensions.—Length of the shell (with eleven joints) 0.28, breadth 0.09; length of the tenth joint 0.02, of the last joint 0.1.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 634. Cyrtopera,^[139] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichoperida (vel Stichocyrtida triradiata clausa) with three latticed lateral wings, or three longitudinal rows of lattice wings. Cephalis with a horn.

The genus Cyrtopera differs from the preceding Stichopera in the fenestration of the three lateral wings, and bears therefore to it the same relation that Sethornithium exhibits to Lithornithium among the Tricyrtida.

Subgenus 1. Artopera, Haeckel, 1881, Prodromus, p. 438.

Definition.—Shell with three annular strictures and four joints.

1. Cyrtopera thoracoptera, n. sp. (Pl. 75, fig. 3).

Artopera thoracoptera, Haeckel, 1881, Prodromus et Atlas (loc. cit.).

Shell inflated, with three very deep strictures. Length of the four joints = 2 : 7 : 8 : 6. Cephalis hemispherical, with a slender, prismatic horn, half as long as the shell. Thorax subspherical, in its middle third with three latticed, triangular wings of half the length. Abdomen with inflated third, and inversely hemispherical fourth joint; the third is the broadest. Pores subregular, hexagonal, with thin bars.

Dimensions.—Length of the shell (with four joints) 0.23. Breadth of the third (broadest) joint 0.13. Length of the single joints, a 0.02, b 0.07, c 0.08, d 0.06.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Cyrtopera ornithoptera, n. sp.

Shell broadly ovate, with three slight strictures. Length of the four joints = 1 : 2 : 3 : 4. Cephalis hemispherical, with a slender, pyramidal horn of three times the length. Along the second and third joints arise with broad base three latticed, triangular wings, nearly as long as the whole shell. Abdomen inflated. The fourth joint is the broadest and longest, with hemispherical basal pole. Pores subregular, hexagonal. (Similar to Artopilium longicorne, Pl. 77, fig. 10, but with more closely reticulated network, and perfectly closed mouth.)

Dimensions.—Length of the shell (with four joints) 0.2. Breadth of the fourth (broadest) joint 0.14. Length of the single joints, a 0.02, b 0.04, c 0.06, d 0.08.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

3. Cyrtopera gasteroptera, n. sp.

Shell slenderly ovate, with three distinct strictures. Length of the four joints = 2 : 6 : 7 : 6. Cephalis subspherical, with a stout pyramidal horn of the same length. The three following joints have nearly equal length; the third is the broadest. The thorax exhibits three divergent solid ribs; as prolongations of these, three descending latticed wings, of about the same length, arise from the third joint, with broad triangular base. The fourth joint is inversely conical, blunt. Pores irregular, roundish. (Similar to Hexalatractus fusiformis, Pl. 68, fig. 13, but with three wings and four joints.)

Dimensions.—Length of the shell (with four joints) 0.21. Breadth of the third (broadest) joint 0.11. Length of the single joints, a 0.02, b 0.06, c 0.07, d 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Subgenus 2. Cyrtolagena, Haeckel, 1879, Atlas (Pl. 75).

Definition.—Shell with four or more annular strictures, and five or more joints.

4. Cyrtopera laguncula, n. sp. (Pl. 75, fig. 10).

Cyrtolagena laguncula, Haeckel, 1879, Manuscript et Atlas (loc. cit.).

Shell bottle-shaped, with seven sharp strictures; the upper part is slender, conical, composed of seven joints of nearly equal length; the lower part is only formed by the spherical last joint. Cephalis subspherical, with a slender curved horn at three times the length. Along the whole shell arise three longitudinal combs or rows of ascending spines (three on each joint, fifteen on the last). These are connected by three divergent longitudinal rods, so that three elegant fenestrated ribs are formed (each rib with one series of large square meshes). Pores in the seven upper joints regular, circular, in the last polygonal, irregular and larger.

Dimensions.—Length of the shell (with eight joints) 0.17, of the last joint 0.08; breadth 0.08.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

5. Cyrtopera lagenella, n. sp.

Shell bottle-shaped, with twelve sharp strictures, very similar in form and structure to the preceding species; but instead of the three simple fenestrated ribs there arise here, along the shell, three series of short, triangular, latticed wings. The four first and the last joints are without wings. The hemispherical cephalis bears a curved conical horn, as long as the subspherical last joint. The twelve joints of the upper conical part are nearly equal in length, with regular, small, hexagonal pores. The last inflated joint is one-third as long as the shell, and has larger, irregular, polygonal pores.

Dimensions.—Length of the shell (with thirteen joints) 0.25, of the last joint 0.08; breadth 0.1.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

Genus 635. Artopera,^[140] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichoperida with three solid lateral ribs or wings, and with a vertical basal spine on the end of the pointed last joint. Cephalis with a horn.

The genus Artopera differs from its ancestral genus, Stichopera, in the development of a vertical terminal spine on the end of the last joint, and bears therefore to it the same relation that Rhopalatractus exhibits to Rhopalocanium among the Tricyrtida.

1. Artopera loxia, Haeckel.

Lithornithium loxia, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 8; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 78, Taf. iv. fig. 8.

Shell spindle-shaped, with three deep strictures. Length of the four joints = 2 : 5 : 5 : 4. Cephalis subspherical, hyaline, without pores, with a thick conical horn of the same length. From the two following joints, which are nearly equal in size and of campanulate form, arise, with broad base, three divergent, slender, triangular wings. The fourth joint is smaller, inversely conical, and bears on the basal pole a strong, three-sided pyramidal, vertical spine, half as long as the shell. Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.07. Length of the single joints, a 0.02, b 0.055, c 0.055, d 0.05.

Habitat.—Fossil in Barbados.

2. Artopera motacilla, n. sp.

Shell spindle-shaped, with three distinct strictures. Length of the four joints = 1 : 2 : 3 : 2. Cephalis subspherical, with a conical horn of twice the length. From the second joint arise three longitudinal, smooth, divergent ribs, which are prolonged over the third joint, and terminate at the third stricture in three short, conical teeth. The fourth is inversely conical, and bears on the basal pole a strong, vertical, cylindrical spine, nearly half as long as the shell. Pores subregular, circular, hexagonally framed. (Similar to Rhopalatractus pentacanthus, Pl. 68, fig. 11, but differing in the presence of three sharp strictures, and a large, conical, basal joint).

Dimensions.—Length of the shell (with four joints) 0.18. Breadth of third (broadest) joint 0.09. Length of the single joint, a 0.02, b 0.04, c 0.06, d 0.04.

Habitat.—Western Tropical Pacific (Philippine Sea), Station 198, depth 2150 fathoms.

3. Artopera fusiformis, n. sp.

Shell spindle-shaped, with three distinct strictures. Length of the four joints = 2 : 3 : 5 : 5. Cephalis conical, with a strong, conical horn of the same length. Along the three first joints arise three divergent, irregularly dentate ribs, which at the second joint bear stronger, pyramidal teeth, also at the third stricture a strong, terminal tooth. Fourth joint without ribs, inversely conical, with a strong, conical, terminal spine of half the length on the basal pole. Pores subregular, circular, double-edged.

Dimensions.—Length of the shell (with four joints) 0.15. Breadth of the third (broadest) joint 0.08. Length of the single joint, a 0.02, b 0.03, c 0.05, d 0.05.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Family LXIX. Phormocampida, n. fam.

Artophormida et Artophænida, Stichophormida et Stichophænida, Haeckel, 1881, Prodromus, pp. 438, 439.

Definition.—Stichocyrtida multiradiata. (Cyrtoidea with an annulated shell, divided by three or more transverse constrictions into four or more annular joints, with numerous, four to nine or more, radial apophyses.)

The family Phormocampida comprises those Cyrtoidea in which the lattice-shell is composed of numerous (four to eight or more) annular joints, and bears numerous (four to eight or more) radial apophyses. We divide it into two subfamilies, differing in the shape of the terminal mouth. This is a simple wide opening in the Stichophormida (and the united Artophormida), closed by a lattice-plate in the Stichophænida (and the united Artophænida). The phylogenetic origin of the Phormocampida may be found in the Phormocyrtida.

Three fossil forms only of Phormocampida were hitherto known, two of which were described by Stöhr as Eucyrtidium acutatum and Lithocampe fimbriata, the third by Ehrenberg as Eucyrtidium barbadense; the latter belongs to Artophormis, the two former to Cyrtophormis. All the other Phormocampida here described, forming together thirty-one species, are new; twenty-two of them belong to the Stichophormida, and nine to the Stichophænida. The latter are disposed in two, the former in four genera.

The number of the radial apophyses is sometimes six or nine, sometimes twelve or more, usually a multiple of three. They are either lateral ribs or wings (Pl. 75, figs. 2, 5, 12), or terminal feet (Pl. 77, figs. 13 to 18). Usually they are solid, not latticed, and not strongly developed. The majority of Phormocampida have probably been derived from Phormocyrtida by growth of the abdomen, which becomes annulated by transverse constrictions. Some forms, however, may be derived from similar Podocampida, by interpolation of three to six or more secondary apophyses between the three primary or perradial apophyses.

Synopsis of the Genera of Phormocampida.

I. Subfamily Stichophormida. Mouth of the terminal joint open, simple.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell conical or pyramidal. Mouth wide open, not constricted.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Lateral ribs prolonged into the terminal feet,	636. Stichophormis.
				No lateral ribs. Feet free, terminal,	637. Phormocampe.
		Shell ovate or spindle-shaped. Mouth more or less constricted.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Lateral ribs prolonged into the terminal feet,	638. Artophormis.
				No lateral ribs. Feet free, terminal,	639. Cyrtophormis.
II. Subfamily Stichophænida. Mouth of the terminal joint closed by a lattice-plate.	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Six radial ribs or wings,			640. Artophæna.
		Nine radial ribs or wings,			641. Stichophæna.

Subfamily 1. Stichophormida, Haeckel, 1881, Prodromus, p. 439.

Definition.—Phormocampida with the terminal mouth of the shell open (vel Stichocyrtida multiradiata aperta).

Genus 636. Stichophormis,^[141] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichophormida (vel Stichocyrtida multiradiata aperta) with conical or pyramidal shell, bearing in its wall numerous lateral ribs, which are prolonged into terminal feet. Mouth not constricted.

The genus Stichophormis and the three following genera represent together the subfamily of Stichophormida, or of those multiradiate Stichocyrtida in which the mouth remains open; they may be derived therefore either from the Theophormida by increasing the number of the shell-joints, or from the Stichopilida by the interpolation of new radial ribs between the three primary ribs. Stichophormis may have been derived in the former way from Theophormis.

Subgenus 1. Stichophormium, Haeckel.

Definition.—Shell with six prominent longitudinal ribs, which are prolonged into six (sometimes five or seven) divergent free feet over the mouth.

1. Stichophormis pyramidalis, n. sp.

Shell slenderly pyramidal, with three annular septa, and six prominent radial ribs, which arise from the collar-septum, and are prolonged on the mouth into six free, divergent, pyramidal feet, about as long as the shell. Length of the four joints = 2 : 3 : 5 : 8. Cephalis subspherical, with a stout, pyramidal horn of twice the length. Pores regular, circular.

Dimensions.—Length of the shell (with four joints) 0.18, basal breadth 0.08. Length of the single joints, a 0.02, b 0.03, c 0.05, d 0.08.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

2. Stichophormis lucerna, n. sp.

Shell slenderly pyramidal, with three annular septa and six prominent radial ribs, which arise from the second stricture, and are prolonged over the mouth into six free, divergent, cylindrical feet, half as long as the shell. Length of the four joints = 1 : 2 : 3 : 15. Cephalis hemispherical, with a prismatic horn of the same length. Pores in the first and second joints very small and scarce, in the third campanulate joint circular, hexagonally framed, in the colossal fourth joint very large, polygonal (each about as large as the third joint).

Dimensions.—Length of the shell (with four joints) 0.4, basal breadth 0.2. Length of the single joints a 0.02, b 0.04, c 0.06, d 0.3.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Stichophormis cornutella, n. sp. (Pl. 75, fig. 9).

Shell slenderly conical, with nine annular strictures and six longitudinal divergent ribs, which arise in the middle of the shell (from the sixth or seventh stricture), and are prolonged over the wide mouth into six slender bristle-shaped feet, about half as long as the shell. The bases of the feet are connected by arcades of lattice-work. All ten joints have nearly the same length and regular hexagonal pores (in the first and second joints circular). Cephalis hemispherical, with a very large curved horn, nearly half as long as the shell, and on one side decurrent to the fourth or fifth joint.

Dimensions.—Length of the shell (with ten joints) 0.16, of each single joint about 0.016; basal breadth 0.07.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

Subgenus 2. Stichophormiscus, Haeckel.

Definition.—Shell with nine prominent radial ribs, which are prolonged over the mouth into nine (sometimes eight or ten) divergent free feet.

4. Stichophormis novena, n. sp. (Pl. 79, fig. 9).

Shell slenderly conical, very similar to the preceding, but with eleven annular strictures and nine divergent ribs, which arise from the tenth or eleventh stricture, and are prolonged over the wide mouth into nine bristle-shaped feet, half as long as the shell. The length of the twelve joints increases gradually; the tenth is twice as long as the sixth. Pores regular, circular. Cephalis hemispherical, with a curved conical horn of twice the length. (In the somewhat mutilated specimen figured, the horn and the nine feet were broken off, but were well preserved in another specimen, found afterwards.)

Dimensions.—Length of the shell (with twelve joints) 0.22, eighth joint 0.02, fourth joint 0.01; basal breadth 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

5. Stichophormis radiata, n. sp.

Shell slender, conical, with fourteen annular strictures, and nine radial ribs; three primary ribs arise from the third stricture, the other six (secondary) ribs from the ninth stricture; all are prolonged over the mouth into nine slender bristle-shaped feet, about twice as long as one joint. All joints have nearly the same length. Cephalis subspherical, with a straight, conical horn three times the length. Pores regular, hexagonal.

Dimensions.—Length of the shell (with fifteen joints) 0.24, of each joint, about 0.016; basal breadth 0.12.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

Genus 637. Phormocampe,^[142] n. gen.

Definition.—Stichophormida (vel Stichocyrtida multiradiata aperta), with conical or pyramidal shell, without lateral ribs. Mouth dilated, with a corona of terminal feet.

The genus Phormocampe may be derived from the preceding Stichophormis by loss of the lateral ribs, whilst the terminal feet remain. It bears therefore to the latter the same relation that Calocyclas exhibits to Theophormis among the Tricyrtida.

Subgenus 1. Anthocorys, Haeckel, 1881, Prodromus, p. 437.

Definition.—Shell with three transverse strictures or annular septa, and with four distinct joints.

1. Phormocampe campanula, n. sp. (Pl. 77, fig. 13).

Anthocorys campanula, Haeckel, 1881, Prodromus et Atlas (loc. cit.).

Shell campanulate, with three internal, annular septa. Length of the four joints = 5 : 2 : 8 : 3. Cephalis three-sided, pyramidal, slender, bearing a pyramidal horn of the same length, with three dentate edges. Thorax very small, hemispherical. Third joint very large, campanulate. Fourth joint of the same breadth, but only one-third as long. Pores subregular, circular. Peristome with a coronal of twelve to fifteen conical, divergent feet, as long as the last joint.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.09. Length of the single joints, a 0.05, b 0.02, c 0.08, d 0.03.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

2. Phormocampe lamprocyclas, n. sp. (Pl. 77, fig. 16).

Shell conical, with three internal annular septa. Length of the four joints = 1 : 1 : 3 : 4. Cephalis subspherical, as large as the thorax, with a stout, pyramidal horn of three times the length, bearing at the apex a spinulate knob. The fourth joint is the broadest, and has large, circular, hexagonally-framed pores, two to three times as broad as the circular pores of the three first joints. Peristome with a double coronal of short, conical, divergent feet, nine on each coronal.

Dimensions.—Length of the shell (with four joints) 0.16, breadth 0.11. Length of the single joints, a 0.02, b 0.02, c 0.05, d 0.07.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

3. Phormocampe eucalyptra, n. sp. (Pl. 77, fig. 14).

Shell flatly conical, somewhat broader than long, with four internal annular septa. The four joints increase gradually in length and breadth. Pores subregular, hexagonal. Cephalis hemispherical, with two small, divergent horns. Peristome with a coronal of thirty to forty short, conical, divergent feet.

Dimensions.—Length of the shell 0.14, breadth 0.17. Length of the single joints, a 0.02, b 0.03, c 0.04, d 0.05.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

4. Phormocampe metalis, n. sp.

Shell spiny, with three broad internal annular septa. Three of the four joints are nearly equal in length, each being three times as long as the first. Cephalis subspherical, with a conical horn of twice the length. The second and third joints are together nearly ellipsoidal, and are not separated externally. The fourth joint is separated from them by a deep stricture, one and a half times as broad, and flatly conical. Pores subregular, circular, hexagonally framed. Peristome with a coronal of twenty to thirty strong, conical, divergent feet.

Dimensions.—Length of the shell 0.22, basal breadth 0.16. Length of the single joint, a 0.02, b 0.06, c 0.06, d 0.08.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

Subgenus 2. Cyrtocorys, Haeckel, 1881, Prodromus, p. 438.

Definition.—Shell with four or more transverse strictures, and five or more joints.

5. Phormocampe mitra, n. sp.

Shell broadly campanulate, conical, about as broad as long, with five internal annular septa. Length of the six joints gradually increasing. Cephalis flat, cap-shaped, with a short, bristle-shaped, conical horn. Pores small and numerous, regular, hexagonal, with thin bars. Peristome with a coronal of forty to fifty divergent, bristle-shaped feet, about as long as the last joint.

Dimensions.—Length of the shell (with six joints) 0.16, of the last joint 0.05; breadth 0.18.

Habitat.—North Pacific, Station 235 (off Japan), surface.

6. Phormocampe conus, n. sp.

Shell slenderly conical, three times as long as broad, with thirteen distinct strictures. Length of the fourteen joints nearly equal. Breadth gradually increasing towards the mouth. Cephalis hemispherical, with a slender, conical, curved horn of three times the length. Pores small and numerous, regular, circular. Peristome with a coronal of twenty to thirty slightly divergent, bristle-shaped feet, twice as long as the last joint.

Dimensions.—Length of the shell (with fourteen joints) 0.22, of each joint (on an average) 0.016; basal breadth 0.08.

Habitat.—South Pacific, Station 297, surface.

Genus 638. Artophormis,^[143] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichophormida (vel Stichocyrtida multiradiata aperta) with ovate or spindle-shaped shell, bearing in its wall numerous lateral ribs, which are prolonged into terminal feet. Mouth constricted.

The genus Artophormis and the following Cyrtophormis differ from the two preceding genera in the ovate form of the shell, which tapers in breadth towards the constricted mouth. It differs from the similar Alacorys in the greater number of the shell-joints, this being four or more.

1. Artophormis horrida, n. sp. (Pl. 75, fig. 2).

Shell slenderly ovate, spiny, with three deep strictures, twice as long as broad. Length of the four joints = 2 : 5 : 6 : 7. Whole surface covered with strong conical spines. Six prominent, longitudinal ribs, decurrent from the cephalis to the mouth, are armed with larger spines, which in the upper joints are directed upwards, in the lower downwards. The six ribs are prolonged over the constricted mouth into six stout, conical feet. Cephalis subspherical, with a conical horn and some smaller spines. Pores circular, of very different sizes.

Dimensions.—Length of the shell (with four joints) 0.2, breadth 0.1. Length of the single joints, a 0.02, b 0.05, c 0.06, d 0.07.

Habitat.—South Pacific, Station 300, depth 1375 fathoms.

2. Artophormis costata, n. sp.

Shell spindle-shaped, rough, with six distinct strictures, three times as long as broad. The length of the seven joints increases gradually; the last joint is twice as long as the fifth. Six prominent, radial ribs arise from the third stricture, and are prolonged into six slender, convergent, conical feet, as long as the sixth joint. Cephalis hemispherical, with a pyramidal horn of twice the length. Pores regular, circular.

Dimensions.—Length of the shell (with seven joints) 0.24, breadth 0.08. Length of the last joint 0.05.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

3. Artophormis barbadensis, Haeckel.

Calocyclas barbadensis, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xviii. fig. 8.

Shell slenderly ovate, smooth, with three sharp strictures, twice as long as broad. Length of the four joints = 1 : 2 : 3 : 2. Nine prominent longitudinal ribs arise from the third joint, and are prolonged into nine slender, conical, little convergent feet. Cephalis hemispherical, with a conical horn of the same length. Pores subregular, circular, twice as large in the third joint as in the second; the fourth joint bears above a circle of nine very large pores (alternate with the nine ribs), and below two or three circles of smaller pores (eighteen to twenty-seven in the circumference). Mouth somewhat constricted. The figure of Ehrenberg is incomplete, the horn of the cephalis and the nine feet being broken off.

Dimensions.—Length of the shell (with four joints) 0.16, breadth 0.08. Length of the single joints, a 0.02, b 0.04, c 0.06, d 0.04.

Habitat.—Fossil in Barbados.

Genus 639. Cyrtophormis,^[144] n. gen.

Definition.—Stichophormida (vel Stichocyrtida multiradiata aperta) with ovate or spindle-shaped shell, without lateral ribs. Mouth constricted, with a corona of terminal feet.

The genus Cyrtophormis may be derived from the preceding Artophormis by reduction of the lateral ribs, whilst the terminal feet (as their free prolongations) remain, and form a corona around the mouth. Sometimes also each constriction bears a corona of spines. It corresponds to Calocyclas among the Tricyrtida and Anthocyrtis among the Dicyrtida.

Subgenus 1. Cyrtophormium, Haeckel.

Definition.—Shell with six (sometimes five or seven) feet on the peristome (three perradial alternate with three interradial).

1. Cyrtophormis armata, n. sp. (Pl. 78, fig. 17).

Shell spiny, spindle-shaped, with three annular septa. Length of the four joints = 3 : 4 : 5 : 6. The third joint is the broadest, being twice as broad as the constricted mouth. Pores irregular, roundish. Cephalis conical, armed with a bunch of strong, conical spines, and distinguished by double-contoured pores. Peristome with six (sometimes five or seven) triangular, vertical, parallel, or slightly divergent feet.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.09. Length of the single joints, a 0.03, b 0.04, c 0.05, d 0.06.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

2. Cyrtophormis ovata, n. sp.

Shell rough, ovate, very thick-walled, with three distinct strictures. Length of the four joints = 1 : 1 : 2 : 3. The fourth joint is the broadest, inversely hemispherical, and three times as broad as the constricted mouth. Pores regular, circular, hexagonally framed. Cephalis hemispherical, with a pyramidal horn of the same length. Peristome with a coronal of six short, conical, curved, outwardly convex teeth.

Dimensions.—Length of the shell (with four joints) 0.2, breadth 0.14. Length of the single joints, a 0.02, b 0.03, c 0.06, d 0.09.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Subgenus 2. Cyrtophormiscus, Haeckel.

Definition.—Shell with nine (sometimes eight or ten) feet on the peristome (three perradial alternate with six interradial).

3. Cyrtophormis cingulata, n. sp. (Pl. 78, fig. 18).

Shell spiny, spindle-shaped, with three internal annular septa, and three external girdles of spines. The second and third joints are of nearly equal length, twice as broad as the first, and half as broad as the fourth joint. The third joint is the broadest, and twice as broad as the constricted mouth. Pores subregular, circular. Cephalis hemispherical, with a large apical horn, and a coronal of six strong ascending spines. Peristome beyond the stricture of the mouth somewhat dilated, with nine triangular, divergent teeth (broken off in the specimen figured).

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.09. Length of the single joints, a 0.02, b 0.04, c 0.04, d 0.08.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

4. Cyrtophormis aculeata, n. sp.

Shell spiny, slenderly ovate, with five distinct strictures, each with a girdle of spines. The three middle joints are of nearly equal length, each half as long as the second, and one-third as long as the sixth joint. The fifth joint is the broadest, twice as broad as the constricted mouth. Pores regular, circular. Cephalis conical, with a bunch of strong, divergent spines. Peristome with nine strong, conical, vertical, parallel teeth.

Dimensions.—Length of the shell (with six joints) 0.18, breadth 0.08. Length of the first joint 0.02, the second 0.04, the three following 0.02, the sixth 0.06.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

5. Cyrtophormis acutata, Haeckel.

Eucyrtidium acutatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 105, Taf. iv. fig. 11.

Shell rough, spindle-shaped, with six annular strictures. The third, fourth, and seventh joints are equal in length, three times as long as the first and the fifth joints. The fourth joint is the broadest, four times as broad as the constricted mouth. Pores irregular, roundish. Cephalis small, subspherical, with a short conical horn. Peristome with nine (?) irregular, triangular, little convergent teeth.

Dimensions.—Length of the shell (with seven joints) 0.22, breadth 0.11. Length of the third, fourth, and seventh joints 0.04.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte (Stöhr).

Subgenus 3. Acanthocyrtis, Haeckel.

Definition.—Shell with numerous (twelve to twenty or more) terminal feet.

6. Cyrtophormis cylindrica, n. sp. (Pl. 77, fig. 17).

Shell rough, subcylindrical, with three annular septa. The fourth cylindrical joint is four times as long as the second and the third joints. These three joints are nearly equal in breadth. Pores small and numerous, almost square, in regular, transverse rows; two to three in the first joint, five to six in the second and in the third, fourteen to sixteen in the fourth joint. Cephalis flat, cap-shaped, with a short, pyramidal horn. Peristome half as broad as the shell, hyaline, with a coronal of numerous, very delicate, vertical feet.

Dimensions.—Length of the shell (with four joints) 0.2, breadth, 0.08. Length of the single joints, a 0.02, b 0.03, c 0.03, d 0.12.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

7. Cyrtophormis corona, n. sp. (Pl. 77, fig. 15).

Shell smooth, conical, ovate, with three deep strictures, about twice as long as broad. The fourth joint is the broadest, inflated, and three times as long as the second and the third joints. Pores small and numerous, circular, in regular, transverse rows; two in the first joint, four in the second and third, and ten in the fourth joint. Cephalis hemispherical, with a stout, pyramidal horn. Peristome two-thirds as broad as the fourth joint, with twelve to fifteen triangular, convergent teeth.

Dimensions.—Length of the shell (with four joints) 0.16, breadth 0.08. Length of the single joints, a 0.01, b 0.03, c 0.03, d 0.09.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

8. Cyrtophormis cornuta, n. sp. (Pl. 77, fig. 18).

Shell thorny, spindle-shaped, with three distinct strictures. Length of the four joints = 2 : 4 : 3 : 5. The third joint is the broadest. Pores circular, of different sizes, in the three first joints double-contoured. Cephalis subspherical, with a large, conical horn of three times the length. The fourth joint is inversely conical, three times as broad as the constricted mouth. Peristome with a coronal of numerous (ten to twenty) irregular, thin, partly forked teeth.

Dimensions.—Length of the shell (with four joints) 0.14, breadth 0.07. Length of the single joints, a 0.02, b 0.04, c 0.03, d 0.05.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

9. Cyrtophormis fimbriata, Haeckel.

Lithocampe fimbriata, Stöhr, 1880, Palæontogr., vol. xxvi. p. 103, pl. iv. fig. 3.

Shell rough, spindle-shaped, with six annular septa. The fifth joint is the longest, twice as long as each of the three preceding joints, and four times as long as the sixth. The fourth joint is the broadest, three times as broad as the constricted mouth. Pores small, regular, circular. Cephalis small, subspherical, with a small, conical horn (broken off in the specimen figured). Peristome with an irregular, double coronal of ten to twenty vertical teeth.

Dimensions.—Length of the shell (with seven joints) 0.25, breadth 0.1. Length of the fifth joint 0.06, of each of the three preceding 0.03.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; fossil in Sicily (Grotte, Caltanisetta).

10. Cyrtophormis turrita, n. sp.

Shell smooth, nearly conical, twice as long as broad, with twelve sharp strictures. The thirteen joints increase gradually in length and breadth. The last joint is much longer than any of the others, twice as long as the eleventh, and twice as broad as the ninth joint. The constricted mouth on its lower surface is only one-third as broad. Cephalis small, hemispherical, with a short, conical horn. Peristome with a coronal of twenty to thirty delicate, partly confluent, vertical teeth.

Dimensions.—Length of the shell (with thirteen joints) 0.26, breadth 0.12.

Habitat.—South-Eastern Pacific, Station 299 (off Valparaiso), depth 2160 fathoms.

11. Cyrtophormis turricula, n. sp. (Pl. 75, fig. 5).

Shell smooth, slender, tower-shaped, with fourteen distinct strictures. The ten first joints are nearly equal in length. The twelfth joint is the largest, three to four times as long as each of the preceding, and broader than all the others, twice as broad as the suddenly constricted mouth. Pores small and numerous, regular, circular, quincuncial. Cephalis small, subspherical, with a pyramidal horn of three times the length. Peristome with a coronal of twenty to thirty very delicate, partly confluent, short, vertical teeth.

Dimensions.—Length of the shell (with fifteen joints) 0.3, breadth 0.1. Length of the twelfth joint 0.05.

Habitat.—South-Eastern Pacific, Station 298 (off Valparaiso), depth 2225 fathoms.

Subfamily 2. Stichophænida, Haeckel, 1881, Prodromus, p. 439.

Definition.—Phormocampida with the terminal mouth of the shell fenestrated (vel Stichocyrtida multiradiata clausa).

Genus 640. Artophæna,^[145] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichophænida (vel Stichocyrtida multiradiata clausa) with six radial ribs or wings.

The genus Artophæna and the following genus Stichophæna represent together the small subfamily of Stichophænida, or of those Cyrtoidea in which the multiradiate shell is composed of numerous (four or more) joints, and closed at the end by a lattice-plate. The number of the lateral, solid, or latticed appendages is six in Artophæna, nine in Stichophæna. They may have been derived either from the Stichophormida by closure of the terminal mouth, or from the Stichoperida by intercalation of three or six interradial appendages.

1. Artophæna ærostatica, n. sp. (Pl. 75, fig. 4).

Shell four-jointed, with three sharp strictures and internal septa. The fourth joint is subspherical, longer than the three first joints together, and twice as broad as these. The second joint is twice as long as the first and the third, and armed with six divergent, stout, pyramidal, radial spines or wings of the same length. Cephalis flat, cap-shaped, with an oblique pyramidal horn of twice the length. Pores regular, circular, hexagonally framed.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.12. Length of the single joints, a 0.02, b 0.04, c 0.02, d 0.1.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Artophæna senaria, n. sp.

Shell pear-shaped, with five distinct strictures. Length of the four middle joints little different. The fifth joint is the broadest. From the first stricture there arise six radial ribs, which at the fourth are prominent as six short, conical, divergent spines. The last joint is inversely hemispherical, twice as long as the preceding. Cephalis hemispherical, with a conical horn of the same length. Pores regular, circular.

Dimensions.—Length of the shell (with six joints) 0.14, breadth 0.09; of each joint 0.02, of the last 0.04.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

3. Artophæna hexalatractus, n. sp.

Shell spindle-shaped, with three sharp strictures, and six triangular, latticed, divergent wings, which arise from the collar stricture and descend along the two middle joints. Their terminal points fall into the same plane as the basal end of the fourth inversely conical joint. Length of the four joints = 1 : 2 : 4 : 2. Cephalis hemispherical, with a conical horn of the same length. (Similar to Theophæna hexaptera, Pl. 68, fig. 13, but with three distinct internal annular septa, corresponding to the three external strictures.)

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.08. Length of the four single joints, a 0.02, b 0.04, c 0.08, d 0.04.

Habitat.—South Pacific (off Juan Fernandez), Station 300, depth 1375 fathoms.

4. Artophæna hexapodiscus, n. sp.

Shell ovate, without external strictures, but with five internal annular septa. Length of the six joints = 1 : 2 : 3 : 4 : 3 : 6. Cephalis hemispherical, with a stout conical horn of twice the length. The last joint is the broadest, inversely hemispherical. From the fourth and fifth joints arise six divergent ribs, which are prolonged over the fifth stricture into six triangular, divergent, fenestrated feet, about as long as the last joint. Pores in the upper half of the shell regular, circular, in the lower half irregular, roundish.

Dimensions.—Length of the shell (with six joints) 0.2, breadth 0.12. Length of the single joints, a 0.015, b 0.025, c 0.03, d 0.04, e 0.03, f 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 641. Stichophæna,^[146] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichophænida (vel Stichocyrtida multiradiata clausa) with nine radial ribs or wings.

The genus Stichophæna differs from the preceding Artophæna in the typical number of the radial lateral appendages, being nine in the former, six in the latter. Usually these are simple ribs enclosed in the shell-wall, more rarely prominent wings.

Subgenus 1. Stichophænidium, Haeckel.

Definition.—Last joint of the shell rounded, without basal spines.

1. Stichophæna ritteriana, n. sp. (Pl. 75, fig. 12).

Shell pear-shaped, twice as long as broad, with seven internal annular septa. The upper half is slenderly conical, composed of seven joints of nearly equal length, gradually increasing in breadth. The lower half is formed only by the eighth joint, which is very large, subglobose, inflated, and as long as the seven other joints together. The spherical cephalis bears a conical horn of the same length. From the thorax arise at equal distances nine radial ribs in the form of thin, triangular lamellæ, which attain their greatest height in the sixth joint, and form nine elegant, denticulate crests in the eighth joint. Pores small and numerous, subregular, circular. This beautiful species is dedicated to my honourable friend, Dr. Paul von Ritter, the magnanimous philanthropist and liberal protector of free science, who founded in the University of Jena the first professorial chair of Darwinism and phylogeny.

Dimensions.—Length of the shell (with eight joints) 0.24, breadth 0.12. Length of each of the first seven joints 0.015; diameter of the subspherical last joint 0.12.

Habitat.—South Pacific, Station 300 (off Juan Fernandez), depth 1375 fathoms.

2. Stichophæna darwiniana, n. sp.

Shell pear-shaped, twice as long as broad, with six distinct strictures. The last joint is the broadest and twice as long as the sixth, three times as long as each of the five preceding joints. The hemispherical cephalis bears a conical horn of twice the length. From the third joint arise nine radial ribs, which reach the sixth joint, but are not developed in the last hemispherical joint. Pores irregular, roundish.

Dimensions.—Length of the shell (with seven joints) 0.2, breadth 0.1. Length of five first joints, each 0.018 to 0.022, of the sixth 0.03, of the seventh joint 0.06.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Stichophæna gœtheana, n. sp.

Shell ovate, one and a half times as long as broad, rough, with five internal annular septa. The six joints gradually increase in length and breadth. The last joint is the broadest, and half as long as the five others together. The hemispherical cephalis bears a pyramidal horn of twice the length. From the thorax arise nine radial ribs, which attain their greatest height in the fourth joint and reach the fifth joint, but are not developed in the last ovate joint. Pores subregular, circular.

Dimensions.—Length of the shell (with six joints) 0.22, breadth 0.14. Length of the single joints, a 0.02, b 0.025, c 0.03, d 0.035, e 0.04, f 0.7.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Subgenus 2. Stichophænoma, Haeckel.

Definition.—Last joint of the shell pointed, armed with a polar, basal spine, or a bunch of spines.

4. Stichophæna nonaria, n. sp. (Pl. 76, fig. 6).

Shell nearly spindle-shaped, with five or six distinct strictures. The third joint is the broadest and longest, and twice as long as the second and the fifth joints. Along the second or third middle joint (beginning from the second or third) descend nine prominent longitudinal ribs. Cephalis hemispherical, with two short, conical, divergent horns. Last joint inversely conical, armed with several strong, conical, divergent spines.

Dimensions.—Length of the shell (with seven joints) 0.23, of the third joint 0.05, of the last 0.04; breadth 0.1.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

5. Stichophæna novena, n. sp. (Pl. 76, fig. 7).

Shell nearly spindle-shaped, with eight or nine deep strictures. The third joint is the broadest, campanulate, in its lower half with nine prominent ribs, which disappear beyond the third stricture. The following joints are alternately longer and shorter, and decrease gradually in breadth. Thorax hemispherical. Cephalis small, hemispherical, with a conical horn of the same length. Last joint also hemispherical, scarcely larger than the cephalis, with a bunch of conical, divergent spines.

Dimensions.—Length of the shell (with nine joints) 0.25, of the third joint 0.05, of the last 0.02; breadth 0.1.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Family LXX. Lithocampida, n. fam.

Artocorida et Artocapsida, Stichocorida et Stichocapsida, Haeckel, 1881, Prodromus, pp. 437-439.

Definition.—Stichocyrtida eradiata. (Cyrtoidea with an annulated shell, divided by three or more transverse constrictions into four or more annular joints, without radial apophyses.)

The family Lithocampida comprises those Cyrtoidea in which the lattice-shell is composed of numerous (four to eight or more) annular joints, and bears no radial apophyses. It may be divided into two subfamilies, differing in the shape of the terminal mouth. This is a simple wide opening in the Stichocorida (and the united Artocorida), closed by a lattice-plate in the Stichocapsida (and the allied Artocapsida). The phylogenetic origin of the Lithocampida may be found in the Theocyrtida.

The number of species of Lithocampida is very great, and amounts here to more than one hundred and sixty whilst the total number of Stichocyrtida is about two hundred and forty. They represent therefore, two-thirds of the whole group, whilst one third is composed of the Podocampida and Phormocampida. Ehrenberg has already described between forty and fifty species in his genera Eucyrtidium and Lithocampe; the majority of these were fossils from Barbados.

This large number of species may be easily increased by accurate researches on the great masses of Lithocampida, which are found in the Radiolarian ooze of the Challenger, and as fossils in Barbados. The variety in the number, size, and proportion of the shell-joints and of the lattice-pores is very great, and permits us to distinguish a far greater number of species than are here described. Many species are cosmopolitan, and belong to the most common forms of Radiolaria.

This large number of species requires to be disposed in different genera, but the distinction of these latter is a rather difficult task, since the exterior of the shell, as well as its internal structure, offers no striking differences (compare Pls. 78 to 80). In my Monograph (1862, pp. 312 to 319) I have already pointed out the difficulty of distinguishing between Lithocampe and Eucyrtidium. The general form of the shell exhibits a continuous series of transformations, from a flat, conical, or nearly discoidal form, through cylindrical to ovate, or spindle-shaped shells, the wide open terminal mouth becoming more or less constricted, and finally (in the Stichocapsida) closed. The absence or presence of an apical horn may further serve for the distinction of genera. A peculiar small group is represented by the Spirocampida (Spirocyrtis, Spirocampe, Pl. 76, figs. 11 to 17), the transverse latticed girdles separating the single joints, which are usually parallel and horizontal, becoming here partly connected, so that they form a descending spiral.

Synopsis of the Genera of Lithocampida.

I. Subfamily Stichocorida. Terminal mouth of the last shell-joint a simple wide opening.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	All annular septa or transverse strictures of the shell separated, parallel, not connected by a spiral line.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Shell conical or cylindrical. Mouth of the last joint wide open, not distinctly constricted.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Conical, gradually dilated.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	With horn,	642. Lithostrobus.
								No horn,	643. Dictyomitra.
						Conical above, cylindrical below.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	With horn,	644. Stichocorys.
						Cylindrical or subcylindrical.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	With horn,	645. Artostrobus.
								No horn,	646. Lithomitra.
				Shell ovate or spindle-shaped. Mouth of the last joint constricted.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Cephalis with a horn.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Last joint not tubular,	647. Eucyrtidium.
								Last joint a long tube,	648. Eusyringium.
						Cephalis without horn.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Cephalis with tube.	649. Siphocampe.
								Cephalis without tube,	650. Lithocampe.
		Annular septa or transverse strictures of the shell all or partly obliquely descending and connected spirally.					$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	With horn,	651. Spirocyrtis.
								No horn,	652. Spirocampe.
II. Subfamily Stichocapsida. Terminal mouth closed by a lattice-plate.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Last joint rounded, without a vertical basal spine.					$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	With horn,	653. Cyrtocapsa.
								No horn,	654. Stichocapsa.
		Last joint conical, pointed, with a vertical, basal spine.					$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Cephalis with horn,	655. Artocapsa.

Subfamily 1. Stichocorida, Haeckel, 1881, Prodromus, p. 438.

Definition.—Lithocampida with the terminal mouth of the shell open (vel Stichocyrtida eradiata aperta).

Genus 642. Lithostrobus,^[147] Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta), with conical shell, gradually dilated towards the wide open mouth. Cephalis with a horn.

The genus Lithostrobus is probably the most primitive among the Lithocampida, and comprises those forms of this family in which the slender, conical shell is gradually dilated towards the wide, terminal mouth, each joint being broader than the preceding. It may be derived from Theoconus by increase in the number of the joints. Some species are distinguished by a curved axis, which gives them a horn-like appearance; these may be separated as a peculiar genus, Cornustrobus.

Subgenus 1. Conostrobus, Haeckel.

Definition.—Shell regularly conical, with straight axis; all joints nearly equal in length, gradually increasing in breadth.

1. Lithostrobus monostichus, n. sp.

Shell slenderly conical, smooth, with straight axis, and eight to ten deep strictures. All joints nearly of the same length, gradually increasing in breadth; the eighth joint twice as broad as the fourth. In each joint only a single transverse series of small, circular, regular pores. Horn of the cephalis conical, straight, of twice the length. (Similar to Lithostrobus tetrastichus, Pl. 80, fig. 6, but in each joint there is only a single series of pores.)

Dimensions.—Length of the shell (with ten joints) 0.2, of each joint 0.02; breadth of the fourth joint 0.03, of the eight 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Lithostrobus distichus, n. sp.

Shell conical, papillate, with straight axis, and four to six deep strictures. All joints nearly of the same length, the fifth twice as broad as the second. In each joint two transverse rows of large, circular pores. Horn of the cephalis stout, straight, conical, of the same length.

Dimensions.—Length of the shell (with six joints) 0.18, of each joint 0.03; breadth of the second joint 0.04, of the fifth 0.08.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

3. Lithostrobus tristichus, Haeckel.

Lithostrobus cuspidatus, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529. Eucyrtidium cuspidatum, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii, p. 5, pl. i. fig. 12.

Shell slenderly conical, smooth, with straight axis, and eight to ten deep strictures. All joints nearly of the same length, the eighth joint twice as broad as the third. In each joint three transverse rows of pores. Horn of the cephalis bristle-shaped, strongly curved, about as long as the shell (Ehrenberg confounds this species with Lithostrobus cuspidatus).

Dimensions.—Length of the shell (with eight joints) 0.16, of each joint 0.02; breadth of the fourth joint 0.04, of the eighth 0.08.

Habitat.—North Pacific, Kamtschatka (Bailey); Station 241, depth 2300 fathoms.

4. Lithostrobus tetrastichus, n. sp. (Pl. 80, fig. 6).

Shell slenderly conical, smooth, with straight axis and six to eight deep strictures. All joints nearly of the same length, the eighth joint twice as broad as the second. In each joint four transverse rows of regular, circular pores with very thin bars. Horn of the cephalis conical, strong, curved, about as long as two joints.

Dimensions.—Length of the shell (with eight joints) 0.12, of each joint 0.015; breadth of the second joint 0.02, of the eighth 0.04.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

5. Lithostrobus pentastichus, n. sp.

Shell slenderly conical, smooth, with straight axis, and six to eight slight strictures. All joints nearly of the same length, the sixth twice as broad as the third. In each joint five transverse rows of small circular pores. Horn of the cephalis pyramidal, of twice the length. (Similar to Eucyrtidium cienkowskii, Pl. 80, fig. 9, but regularly conical, with all the joints equal in length.)

Dimensions.—Length of the shell (with eight joints) 0.2, of each joint 0.025; breadth of the third joint 0.04, of the sixth 0.08.

Habitat.—South Pacific, Station 298, depth 2225 fathoms.

6. Lithostrobus hexastichus, n. sp. (Pl. 80, fig. 15).

Shell campanulate-conical, smooth, with straight axis, and six to eight slight strictures. All joints nearly of the same length, the sixth joint twice as broad as the second. In each joint six transverse rows of subregular, hexagonal pores, with thin bars. Horn of the cephalis conical, straight, of about the same length. (The specimen figured is a somewhat irregular one; other specimens found afterwards were perfectly conical and regular, with joints of equal length).

Dimensions.—Length of the shell (with six joints) 0.16, of each joint 0.027.

Habitat.—Central Pacific, Station 270 to 274, depth 2350 to 2925 fathoms.

Subgenus 2. Cornustrobus, Haeckel.

Definition.—Shell horn-shaped, conical, with curved axis; all joints nearly equal in length, gradually increasing in breadth.

7. Lithostrobus cyrtoceras, n. sp. (Pl. 80, fig. 2).

Shell horn-shaped, conical, with curved axis, smooth, with six to eight deep strictures. All joints nearly of the same length, gradually increasing in breadth; the sixth joint twice as broad as the second. In each joint about four transverse series of regular circular pores. Horn of the cephalis conical, slightly curved, of the same length.

Dimensions.—Length of the curved axis of the shell (with eight joints) 0.24, length of each joint 0.03; breadth of the second joint 0.04, of the sixth 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

8. Lithostrobus leptoceras, n. sp.

Shell horn-shaped, slenderly conical, with curved axis (like a quadrant of a circle), smooth, with twelve to fourteen slight strictures. All joints nearly of the same length, the tenth twice as broad as the second. In each joint only a single transverse row of small circular pores. Horn of the cephalis curved, bristle-shaped, half as long as the shell.

Dimensions.—Length of the curved axis of the shell (with twelve joints) 0.18, length of each joint 0.15; breadth of the second joint 0.02, of the tenth 0.04.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

9. Lithostrobus caloceras, n. sp. (Pl. 80, fig. 4).

Shell horn-shaped, conical, with curved axis, smooth, with six to eight deep strictures. All joints nearly of the same length, the sixth twice as broad as the third. On each joint a single circle of very large roundish pores, separated by two to four series of smaller pores. Horn of the cephalis conical, curved, of twice the length.

Dimensions.—Length of the curved axis of the shell (with six joints) 0.12, length of each joint 0.02; breadth of the third joint 0.04, of the sixth 0.08.

Habitat.—South Pacific, Station 297, depth 1775 fathoms.

10. Lithostrobus macroceras, n. sp.

Shell horn-shaped, slenderly conical, with curved, nearly semicircular axis, without external strictures, but with twelve to twenty internal septal rings. All joints nearly of the same length, the twelfth twice as broad as the third. On each joint three to four transverse rows of subregular, small, hexagonal pores. Horn of the cephalis conical, curved, of twice the length.

Dimensions.—Length of the curved axis of the shell (with sixteen joints) 0.32, length of each joint 0.02; breadth of the third joint 0.02, of the twelfth 0.04.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Subgenus 3. Cyrtostrobus, Haeckel.

Definition.—Shell conical (often more campanulate or irregular), with straight axis; joints of different lengths. Cephalis not lobate.

11. Lithostrobus conulus, n. sp. (Pl. 80, fig. 1).

Shell slenderly conical, smooth, with straight axis, and seven to ten distinct strictures. Joints of different lengths; the fourth and fifth about twice as long as the preceding and following joints, the former with four to five, the latter with two to three transverse rows of large irregular pores; the seventh joint twice as broad as the third. Horn of the cephalis short, pyramidal.

Dimensions.—Length of the shell (with eight joints) 0.14, length of the fifth joint 0.03; breadth 0.06.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

12. Lithostrobus picus, Bütschli.

Lithostrobus picus, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529. Eucyrtidium picus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 1.

Shell slenderly conical, smooth, with straight axis, and six to eight slight strictures. Joints of different lengths, the second twice as long as each of the three following, and four times as long as each of the last joints; the sixth joint one and a-half times as broad as the second. Small circular pores in regular transverse rows; six rows in the first and the second, three rows in the third, fourth, and fifth, a single row in each of the last joints. Horn of the cephalis cylindrical, half as long as the shell.

Dimensions.—Length of the shell (with eight joints) 0.12, length of the second joint 0.03; breadth 0.04.

Habitat.—Fossil in Barbados.

13. Lithostrobus argus, Bütschli.

Lithostrobus argus, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529. Eucyrtidium argus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. ix. fig. 1.

Shell conical, thorny, with straight axis, and five to seven slight strictures. Joints of different lengths, each of the three first twice as long as each of the following. Pores large, roundish, in transverse rows; three rows in the first and the second joints (which in the figure of Ehrenberg are not separated), two rows in the third joint, a single row in each of the following joints. Horn of the cephalis large, conical, curved, half as long as the shell.

Dimensions.—Length of the shell (with seven joints) 0.2, length of the fourth joint (and each following) 0.02; breadth 0.1.

Habitat.—Fossil in Barbados.

14. Lithostrobus acuminatus, Haeckel.

Eucyrtidium acuminatum, Bury, 1862, Polycystins of Barbados, pl. i, fig. 1.

Shell slenderly conical, smooth, with straight axis, and four to six deep strictures. Joints gradually increasing in length. Pores in regular, transverse rows, commonly three rows in the first, four in the second, five in the third, six in the fourth, seven in the fifth, &c. (sometimes the increase of the number is more or less irregular). Horn of the cephalis strong, conical, straight, about as long as the fourth or sixth joint.

Dimensions.—Length of the shell (with six joints) 0.2; length of the fourth joint 0.04, breadth 0.06.

Habitat.—Fossil in Barbados.

15. Lithostrobus cuspidatus, Haeckel.

Eucyrtidium cuspidatum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ii. fig. 15.

Shell, slender, conical, smooth, with straight axis, and ten to twelve distinct strictures. Joints gradually increasing slightly in length, the tenth twice as long as the third. Pores circular, in regular transverse rows; commonly two rows in the first, three in the second, four in the third, seven in the eighth and following joints. Horn of the cephalis long, bristle-shaped, curved. This species called Eucyrtidium cuspidatum by Ehrenberg, differs from Lithostrobus tristichus (compare above), to which Bailey had given the same name.

Dimensions.—Length of the shell (with ten joints) 0.2; length of the tenth joint 0.03, breadth 0.06.

Habitat.—North Atlantic (Greenland, Ehrenberg); Station 348, depth 2450 fathoms.

16. Lithostrobus cornutella, Bütschli.

Lithostrobus cornutella, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529. Eucyrtidium cornutella, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. ii. fig. 14.

Shell slender, conical, smooth, with straight axis, and seven to nine slight strictures. Joints gradually increasing slightly in length, the sixth or seventh about twice as long as the third. Pores circular, in regular transverse rows; two or three in the three or four first joints, three or four in the following, four or five in the last joints. Horn of the cephalis thin, bristle-shaped, curved.

Dimensions.—Length of the shell (with eight joints) 0.1; length of the eighth joint 0.01, breadth 0.04.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific; many stations, surface.

17. Lithostrobus tornatus, Haeckel.

Eucyrtidium tornatum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 292, Taf. ix. fig. 20.

Shell campanulate-conical, smooth, with straight axis, and four to six deep strictures. Joints broad, gradually increasing in length, the fifth twice as long as the second. Pores small, circular, in regular transverse rows; in the second and third joints three or four rows, in the fifth seven rows, &c. Horn of the cephalis small, double or forked.

Dimensions.—Length of the shell (with five joints) 0.1; length of the fifth joint 0.04, breadth 0.08.

Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).

18. Lithostrobus seriatus, n. sp. (Pl. 79, fig. 15).

Shell slender, conical, smooth, with straight axis, and four or five deep strictures. Joints little different in length, increasing towards the inflated last joint, which is twice as long as the preceding. On each joint four or five transverse rows of small circular pores. Horn small, bristle-shaped, oblique. This common species is rather variable.

Dimensions.—Length of the shell (with five joints) 0.14; length of the fifth joint 0.05, breadth 0.06.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

19. Lithostrobus cornutus, n. sp. (Pl. 77, fig. 6).

Shell slender, conical, subcampanulate, smooth, with three or four deep strictures. Joints of different lengths, the third and the fourth twice as long as the second, four times as long as the first. Transverse rows of small circular pores; three in the first joint, five in the second, eight in the third and in the fourth. Horn large, pyramidal, about as long as the third joint.

Dimensions.—Length of the shell (with four joints) 0.12; length of the third joint 0.04, breadth 0.06.

Habitat.—Central Pacific, Station 265 to 268, depth 2700 to 2900 fathoms.

20. Lithostrobus microporus, Bütschli.

Lithostrobus microporus, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529. Eucyrtidium microporum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. xi. fig. 20.

Shell slender, conical, smooth, very similar to the preceding species, differs mainly in the more slender form and the smaller pores. The first joint has four, the second eight, the third ten transverse rows of pores. Horn conical, as long as the cephalis. The third joint in this and the preceding species is campanulate, and large.

Dimensions.—Length of the shell (with four joints) 0.11; length of the third joint 0.05, breadth 0.04.

Habitat.—Fossil in Barbados.

21. Lithostrobus quadratus, n. sp.

Shell broad, conical, smooth, with straight axis, and six to eight deep strictures. Joints of different lengths, usually alternately longer and shorter. The seventh joint five times as broad as long, twice as long as the sixth and the fourth; six transverse rows of pores in the seventh, three in the sixth joint. Horn small, conical. This species differs from all others in the subregular square form of the small pores.

Dimensions.—Length of the shell (with seven joints) 0.15; length of the seventh joint 0.024, breadth 0.12.

Habitat.—Central Pacific, Station 271 to 274, depth 2350 to 2750 fathoms.

22. Lithostrobus hexagonalis, n. sp. (Pl. 79, fig. 20).

Shell broad, conical, smooth, with straight axis, and five to eight prominent girdles between six and nine constricted broad joints. The first and the third joints are half as long as the second, the fourth, and each of the following joints. The sixth joint is five times as broad as long. Pores subregular, hexagonal, in regular transverse rows; three to four rows in the first and the second joints, six to eight in the third, the fourth, and each following joint. Cephalis with some small spines, and a larger, oblique, curved horn.

Dimensions.—Length of the shell (with six joints) 0.2; length of the sixth joint 0.04, breadth 0.2.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

Subgenus 4. Botryostrobus, Haeckel.

Definition.—Shell conical, with straight axis, joints of different lengths. Cephalis lobate, with some irregular constrictions. (Perhaps derived from Botryodea?).

23. Lithostrobus botryocyrtis, n. sp. (Pl. 79, figs. 18, 19).

Shell slender, conical, smooth, with straight axis, and three deep strictures. Joints of different lengths. The length of the fourth joint equals two-thirds of its breadth, and of the length of the three preceding joints together. Each of the latter bears three transverse rows of small, quadrangular pores, the fourth joint has six rows. The cephalis is irregularly lobate, with four to six prominent lobes, and two small divergent horns (fig. 19).

Dimensions.—Length of the shell (with four joints) 0.1; length of the fourth joint 0.04, breadth 0.06.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

24. Lithostrobus lithobotrys, n. sp. (Pl. 79, fig. 17).

Shell slender, conical, smooth, with straight axis, and four deep strictures. Joints of different lengths, gradually increasing towards the mouth, the length of the fifth joint equals half its breadth, and one-third of the length of the whole shell. The single joints bear each four or five transverse rows of small, roundish pores. Cephalis irregularly lobate, with four to six prominent lobes, and the same number of small, conical horns.

Dimensions.—Length of the shell (with five joints) 0.12; length of the fifth joint 0.04, breadth 0.08.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 643. Dictyomitra,^[148] Zittel, 1876, Zeitschr. d. deutsch. geol. Gesellsch., p. 80.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta), with conical shell gradually dilated towards the wide open mouth. Cephalis without horn.

The genus Dictyomitra agrees with the preceding Lithostrobus in the slender, conical form of the multiarticulate shell, but differs from it in the absence of a horn on the cephalis; the horn is here completely lost.

Subgenus 1. Dictyomitrella, Haeckel.

Definition.—Shell smooth, with joints nearly equal in length.

1. Dictyomitra articulata, Haeckel.

Eucyrtidium articulatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. figs. 2, 3.

Shell slender, conical, smooth, with six to eight deep strictures. All joints nearly equal in length, gradually increasing in breadth, the eighth four times as broad as long, and twice as broad as the fourth joint. In each joint three to four transverse series of small, regular, circular pores.

Dimensions.—Length of the shell (with eight joints) 0.12, of each joint 0.015; breadth of the fourth joint 0.04, of the eighth joint 0.08.

Habitat.—Fossil in Barbados.

2. Dictyomitra macilenta, Haeckel.

Eucyrtidium macilentum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 15.

Shell slender, conical, smooth, with five to seven deep strictures. All joints nearly equal in length, gradually increasing in breadth, the sixth joint three times as broad as long, and twice as broad as the second. In each joint only two transverse series of small, regular, circular pores.

Dimensions.—Length of the shell (with seven joints) 0.08, of each joint 0.012; breadth of the sixth joint 0.036, of the second 0.018.

Habitat.—Western Tropical Pacific, Stations 200 to 225, in various depths.

3. Dictyomitra conica, n. sp.

Shell widely conical, with six to eight prominent strictures. All joints nearly equal in length, gradually increasing in breadth, the eighth five times as broad as long, and twice as broad as the third. In each joint three to four transverse rows of regular, hexagonal pores. (Similar to Lithostrobus hexagonalis, Pl. 79, fig. 20, but more slender, and without cephalic horn.)

Dimensions.—Length of the shell (with seven joints) 0.16, of each joint 0.022; breadth of the sixth 0.08.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

Subgenus 2. Dictyomitrissa, Haeckel.

Definition.—Shell smooth, with joints of very different lengths.

4. Dictyomitra polypora, Zittel.

Dictyomitra polypora, Zittel, 1876, Zeitschr. d. deutsch. geol. Gesellsch., p. 80, Taf. ii. fig. 1.

Shell slender, conical, rough, with six to nine deep strictures. Breadth and length of the joints gradually increasing, so that the eighth joint is twice as long and broad as the third. Pores regular, circular, in transverse rows, four rows in each joint, in the last joint five to six rows.

Dimensions.—Length of the shell (with eight joints) 0.24; length of the eighth joint 0.04, breadth 0.1; length of the third joint 0.02, breadth 0.05.

Habitat.—Fossil in secondary rocks of Northern Germany (chalk of Brunswick, &c.), Zittel.

5. Dictyomitra eurythorax, n. sp. (Pl. 77, fig. 4).

Lithocampium eurythorax, Haeckel, 1881, Prodromus, p. 437, et Atlas, pl. lxxvii. fig. 4.

Shell campanulate, conical, rough, with three deep strictures. Cephalis small, hemispherical. Thorax large, inflated, hemispherical, with six transverse rows of pores. Abdomen with two broader joints, together as long as the thorax, each with three to four rows of pores.

Dimensions.—Length of the shell (with four joints) 0.14, of the thorax 0.06; breadth of the thorax 0.08, of the last joint 0.1.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

6. Dictyomitra microcephala, Haeckel.

Eucyrtidium microcephalum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 32; Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, p. 291, Taf. xi. fig. 24.

Shell broadly conical, smooth, with six to eight distinct strictures. Breadth of the joints gradually increasing, length unequal. The three first joints short, only one-half or one-third as long as each of the following joints; in each of the former three to four transverse rows, in each of the latter six to eight transverse rows of small, regular, circular pores.

Dimensions.—Length of the shell (with six joints) 0.09, of the three first joints 0.03, of the three following 0.06; breadth of the sixth joint 0.08, of the fourth 0.04.

Habitat.—Mediterranean (Candia) Spratt, depth 1620 fathoms.

7. Dictyomitra demersissima, Haeckel.

Eucyrtidium demersissimum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. vii. fig. 11.

Shell slender, conical, smooth, with four internal septal rings (without external strictures). Breadth of the five joints gradually increasing, length unequal; the third joint the longest, twice as long as the second, and longer than any of the following. Pores very small and numerous, in longitudinal rows.

Dimensions.—Length of the shell (with five joints) 0.09, of the second joint 0.015, of the third 0.03; breadth of the second joint 0.03, of the third 0.05.

Habitat.—Tropical Pacific, Philippine Sea, depth 3300 fathoms.

Subgenus 3. Dictyomitroma, Haeckel.

Definition.—Shell with longitudinal ribs and furrows between them, with joints of different lengths.

8. Dictyomitra costata, n. sp.

Shell slender, conical, with prominent longitudinal ribs, and six to eight deep strictures. Length of the majority of joints nearly equal, the two or three first joints shorter, the last a little longer. In each joint only a single transverse series of pores at the distal end (one pore in each furrow). (Similar to Siphocampe tubulosa, Pl. 79, fig. 13, but conical, and without cephalic tube.)

Dimensions.—Length of the shell (with eight joints) 0.16, of each middle joint 0.03, of the first 0.02; breadth of the last joint 0.06.

Habitat.—Central Pacific, Station 295, depth 1500 fathoms.

9. Dictyomitra multicostata, Zittel.

Dictyomitra multicostata, Zittel, 1876, Zeitschr. d. deutsch. geol. Gesellsch., p. 81, Taf. ii. figs. 2-4.

Shell slender, conical, with prominent longitudinal ribs, and eight to ten deep strictures. Length and breadth of the joints gradually increasing, the eighth joint twice as long and broad as the fourth joint. Pores regular, circular, one series in each longitudinal furrow, three to four pores on each joint.

Dimensions.—Length of the shell (with eight joints) 0.2, of the fourth joint 0.02, of the eighth joint 0.04; breadth of the fourth joint 0.04, of the eighth 0.08.

Habitat.—Fossil in secondary rocks of North Germany (chalk of Brunswick, &c.), Zittel.

Genus 644. Stichocorys,^[149] Haeckel, 1881, Prodromus, p. 438 (sensu emendato).

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with a middle constriction of the shell, the upper half of which is conical, the lower cylindrical. Mouth truncate. Cephalis with a horn.

The genus Stichocorys is intermediate between the two preceding and the two following genera; the upper half of the shell with the three first joints is conical, the lower half with the fourth and the following joints cylindrical, of equal breadth. The third joint of the shell (or the abdomen of Theoconus) is constantly the largest, being broader than all the other joints. Stichocorys is a very common and characteristic form, and may be derived from Theoconus by development of a post-abdomen.

1. Stichocorys wolffii, n. sp. (Pl. 80, fig. 10).

Shell in the upper half (with three joints) thorny, in the lower half (with two joints) smooth. Pores of the former double-contoured, in subregular, transverse rows. Pores of the latter smaller, simple, scarcely scattered. Cephalis with a pyramidal horn of the same length. Thorax with prominent, longitudinal divergent ribs. Dedicated to Caspar Friedrich Wolff (Halle, 1759).

Dimensions.—Length of the shell (with five joints) 0.16; breadth of the third joint 0.08, of the fourth 0.05.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Stichocorys panderi, n. sp. (Pl. 80, fig. 7).

Shell in the upper conical half (with three joints) spiny, in the lower subcylindrical half (with three joints) smooth. Pores small, circular, irregularly scattered, simple. Cephalis with a conical horn of the same length. No longitudinal ribs. Dedicated to Christian Pander (Würzburg, 1817.)

Dimensions.—Length of the shell (with six joints) 0.18; breadth of the third joint 0.08, of the fourth 0.05.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

3. Stichocorys baerii, n. sp. (Pl. 80, fig. 8).

Shell in the upper conical half (with three joints) spiny, in the lower cylindrical half (with three joints) sulcate, with prominent longitudinal ribs, alternating with longitudinal rows of small pores. Pores of the upper half smaller, quincuncially disposed. Cephalis with a stout pyramidal horn of the same length. Dedicated to Carl Ernst Baer (Königsberg, 1828).

Dimensions.—Length of the shell (with six joints) 0.2; breadth of the third joint 0.09, of the fourth 0.07.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

4. Stichocorys okenii, n. sp. (Pl. 80, fig. 5).

Shell smooth, without spines or ribs; the upper conical half (with three joints) about the same length as the lower subcylindrical half (with three joints). Pores subregular, circular, in the inflated third joint twice as large as in the five other joints. At the lumbar stricture (between the second and third joints) a coronal of nine very large pores. Cephalis with a curved horn of half the length. Dedicated to Lorenz Oken (Jena, 1806).

Dimensions.—Length of the shell (with six joints) 0.2; breadth of the third joint 0.09, of the fourth 0.07.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

5. Stichocorys huschkei, n. sp. (Pl. 80, fig. 3).

Shell in the upper conical half (with three joints) thorny, in the lower cylindrical half (with five joints) smooth, roundish. Pores irregularly scattered, always double-contoured, in the second joint three times as large as in the third. At the third stricture (between the third and fourth joints) a coronal of larger pores. Cephalis with a small, conical horn of half the length. No longitudinal ribs. Dedicated to Emil Huschke (Jena, 1832).

Dimensions.—Length of the shell (with eight joints) 0.18; breadth of the third joint 0.08, of the fourth joint 0.07.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

6. Stichocorys rathkei, n. sp.

Shell spiny, everywhere covered with short conical spines. The upper conical part of the shell (with three joints) half as long as the lower cylindrical part (with six joints). Pores irregular, roundish, in the thorax twice to three times as large as in the eight other joints. Cephalis with a pyramidal horn of the same length. No longitudinal ribs. Dedicated to Heinrich Rathke (Königsberg, 1839).

Dimensions.—Length of the shell (with nine joints) 0.24; breadth of the third joint 0.08, of the fourth joint 0.06.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

7. Stichocorys mülleri, n. sp.

Shell in the upper conical part (with three joints) spiny, in the lower cylindrical part (with seven joints) smooth. Pores in the former irregularly scattered, roundish, in the latter circular, regularly disposed in longitudinal series, alternate, with prominent ribs. The upper conical part of the shell is about half as long as the lower cylindrical part. Cephalis with a large, pyramidal horn of three times the length. Dedicated to Johannes Müller (Berlin, 1858).

Dimensions.—Length of the shell (with ten joints) 0.22; breadth of the third joint 0.09, of the fourth joint 0.06.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

Genus 645. Artostrobus,^[150] n. gen.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with cylindrical shell, the upper pole of which is rounded, the lower truncate. Cephalis with a horn.

The genus Artostrobus and the following Dictyomitra differ from all the other Stichocorida in the cylindrical or nearly cylindrical form of the shell, all the joints of which are nearly equal in breadth, and are very short, often with a single transverse row of pores only. The first joint or cephalis is usually different from the following, often hemispherical or cap-shaped joints. The last joint is truncate, and has a wide open mouth. Since the constrictions between the single joints are often very slight, some species are very similar to the Dicyrtide Sethocorys.

Subgenus 1. Artostrobulus, Haeckel.

Definition.—A single transverse row of small, circular pores on each joint. (Sometimes on the uppermost joints two or three rows.)

1. Artostrobus annulatus, Haeckel.

Cornutella annulata, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii. pl. i. fig. 5a, 5b. Eucyrtidium annulatum, Haeckel, 1862, Monogr. d. Radiol., p. 327.

Shell slender, cylindrical, smooth, without external strictures, but with ten to twenty internal annular septa. On each joint only a single transverse row of small pores. Cephalis hemispherical, with a single or double small horn. Each joint about four times as broad as long.

Dimensions.—Length of the shell (with twenty joints) 0.2; length of each joint 0.01, breadth 0.04.

Habitat.—Arctic Ocean, Kamtschatka (Bailey); Greenland (Ehrenberg).

2. Artostrobus elegans, Haeckel.

? Eucyrtidium elegans, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, pl. xi. fig. 12. ? Eucyrtidium pauperum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, pl. xi. fig. 13.

Shell cylindrical, smooth, with eight to ten internal annular septa. Cephalis subspherical, with a short, conical horn. Thorax campanulate, with two transverse rows of pores. Abdomen with six to eight equal joints, each with a single row of pores. (May be described, perhaps, better as Theocyrtis elegans. Eucyrtidium pauperum, Ehrenberg, loc. cit., may be a variety of this species.)

Dimensions.—Length of the shell (with nine joints) 0.1; length of each abdominal joint 0.01, breadth 0.03.

Habitat.—Fossil in Barbados.

Subgenus 2. Artostrobium, Haeckel.

Definition.—All (or the majority) of the joints of the shell with several transverse rows of pores, in variable number.

3. Artostrobus auritus, Haeckel.

Lithocampe aurita, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 84.

Lithocampe auricula, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 71.

Eucyrtidium auritum, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 25.

Eucyrtidium auritum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 104, Taf. iv. fig. 7.

Shell subcylindrical, with five sharp strictures. All six joints nearly equal in length; each with four or five transverse rows of small pores. Cephalis small, flat, hemispherical, with two or three small, conical, oblique horns. Mouth of the sixth joint a little constricted.

Dimensions.—Length of the shell (with six joints) 0.12; length of each joint (on an average) 0.02, breadth 0.04 to 0.05.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte, Caltanisetta).

4. Artostrobus biseriatus, n. sp.

Shell cylindrical, smooth, with ten to twelve deep strictures. All joints nearly equal in size; each with two transverse rows of small circular pores. Cephalis hemispherical, with a long, bristle-shaped, curved horn.

Dimensions.—Length of the shell (with twelve joints) 0.24; length of each joint 0.02, breadth 0.04.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

5. Artostrobus articulatus, n. sp. (Pl. 79, fig. 16).

Shell subcylindrical, with elegant longitudinal ribs and five sharp strictures. All six joints nearly equal in length, each with three or four transverse rows of small circular pores. The middle joints twice as broad as long. Cephalis hemispherical with a conical, oblique horn.

Dimensions.—Length of the shell (with six joints) 0.16, length of a single joint 0.02 to 0.03, breadth 0.04 to 0.05.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

Genus 646. Lithomitra,^[151] Bütschli, 1882, Zeitschr. f. wiss. Zool., p. 529.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with cylindrical shell, the upper pole of which is rounded, the lower truncate. Cephalis without horn.

The genus Lithomitra differs from the preceding genus Artostrobus in the absence of a cephalic horn, and therefore bears to it the same relation as Dictyomitra does to Lithostrobus. In many species the joints are very short, and bear only a single transverse row of pores, and since the constrictions between the joints are often very slight, Lithomitra becomes very similar to the Dicyrtide Dictyocephalus.

Subgenus 1. Lithomitrella, Haeckel.

Definition.—A single transverse row of small circular pores on each joint. (Sometimes on the uppermost joints two or three rows.)

1. Lithomitra pachyderma, Bütschli.

Lithomitra pachyderma, Bütschli, 1882, Zeitschr. f. wiss. Zool., Vol. xxxvi. p. 529.

Eucyrtidium pachyderma, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 21.

Eucyrtidium imbricatum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. xi. fig. 22.

Shell thick-walled, subcylindrical, with longitudinal ribs, slightly dilated in the middle, with ten to twelve subequal joints. On the lower edge of each joint a single row of small circular pores. No external strictures. This and the following species (though separated by Ehrenberg as four different species) may be united.

Dimensions.—Length of the shell (with ten joints) 0.11; length of each joint 0.01 to 0.012, breadth 0.04.

Habitat.—Fossil in Barbados.

2. Lithomitra acephala, Bütschli.

Lithomitra acephala, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 529.

Eucyrtidium acephalum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 5.

Eucyrtidium obstipum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xi. fig. 17.

Shell nearly cylindrical, smooth, thick-walled, with twelve to sixteen subequal joints. On each joint a single row of small circular pores. No external strictures. Scarcely differing from the preceding species; the joints are broader and shorter, the cephalis is larger (by union of some joints?), and the ribs of the surface less distinct.

Dimensions.—Length of the shell (with twelve joints) 0.1; length of each joint 0.006 to 0.009, breadth 0.04.

Habitat.—Fossil in Barbados.

3. Lithomitra lineata, Haeckel.

Lithocampe lineata, Ehrenberg (partim), 1838, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 130; Mikrogeol., 1854, Taf. xxii. fig. 26.

Lithocampe lineata, Haeckel, 1862, Monogr. d. Radiol., p. 316.

Eucyrtidium lineatum, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 43; Mikrogeol., 1854, Taf. xxxvi. fig. 16; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 72, Taf. xi. fig. 9.

Dictyomitra lineata, Stöhr, 1880, Palæontogr., vol. xxvi. p. 101, Taf. iii. fig. 22.

Shell subcylindrical, smooth, with longitudinal ribs, and four to eight slight transverse strictures. Cephalis small, subspherical, with few small pores. Thorax broader, with two or three transverse rows of pores. Each succeeding (abdominal) joint with a single transverse row of small pores. Variable and nearly related to the two preceding species (compare my Monograph, loc. cit.).

Dimensions.—Length of the shell (with six to eight joints) 0.06 to 0.08; length of each joint (on an average) 0.01, breadth 0.03.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Indian, Pacific, in various depths; many stations; fossil in Secondary and Tertiary rocks of many places.

4. Lithomitra nodosaria, n. sp. (Pl. 79, fig. 1).

Shell subcylindrical, with longitudinal ribs, and five to eight transverse strictures, and prominent girdles between them. On each girdle (at the lowermost edge of each joint) a single transverse row of circular pores. The three or four uppermost joints are united, and represent a conical cephalis.

Dimensions.—Length of the shell (with six joints) 0.1; length of each joint 0.01 to 0.15, breadth 0.04 to 0.06.

Habitat.—Central Pacific, Station 263 to 274, depth 2350 to 2925 fathoms.

5. Lithomitra eruca, n. sp. (Pl. 79, fig. 3).

Shell subcylindrical, diminishing slightly towards both ends, with ten to fifteen slight strictures. On each joint a single transverse row of circular pores, descending obliquely in the wall. The two or three first joints form together a roundish cephalis. Usually each joint is three times as broad as long.

Dimensions.—Length of the shell (with twelve joints) 0.2; length of each joint (on an average) 0.016, breadth 0.05.

Habitat.—Central Pacific, Station 265 to 268, depth 2700 to 2900 fathoms; fossil in Barbados.

6. Lithomitra chrysalis, n. sp. (Pl. 79, fig. 4).

Shell subcylindrical, diminishing slightly towards both ends, with elegant longitudinal ribs, and with five to eight slight strictures. Each of the upper joints with two (or sometimes three) transverse rows of small pores; each of the lower joints with only a single row.

Dimensions.—Length of the shell (with six joints) 0.11; length of each joint 0.01 to 0.015, breadth 0.04 to 0.05.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Subgenus 2. Lithomitrissa, Haeckel.

Definition.—All (or the majority) of the joints of the shell with several transverse rows of pores, in variable number.

7. Lithomitra cylindrica, n. sp.

Shell cylindrical, smooth, with twelve to sixteen internal septal rings (without external strictures). On each joint two transverse rows of small, regular, circular pores. The hemispherical cephalis also has two rows of pores. Each joint is twice as broad as long.

Dimensions.—Length of the shell (with sixteen joints) 0.3; length of each joint 0.02, breadth 0.04.

Habitat.—South Pacific, Station 297, depth 1775 fathoms.

8. Lithomitra costata, Haeckel.

Dictyomitra costata, Stöhr, 1880, Palæontogr., vol. xxvi. p. 101, Taf. iii. fig. 23.

Shell with longitudinal ribs, in the upper half conical, in the lower half cylindrical, with six to eight slight strictures. Small, circular pores in regular transverse rows; three rows in each upper joint, two rows in each lower joint (the last joints sometimes confluent).

Dimensions.—Length of the shell (with eight joints) 0.15; length of each joint 0.017 to 0.023, breadth 0.04 to 0.05.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte (Stöhr), Caltanisetta (Haeckel).

9. Lithomitra punctata, Haeckel.

Lithocampe punctata, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 84.

Eucyrtidium punctatum, Ehrenberg, 1854, Mikrogeol., Taf. xxii. fig. 24.

Dictyomitra punctata, Stöhr, 1880, Palæontogr., vol. xxvi. p. 101, Taf. iii. fig. 24.

Shell subcylindrical, smooth, with four to six distinct strictures. Cephalis small, subspherical. Thorax campanulate-conical. Abdomen cylindrical, with three to four equal joints. In each joint five to six transverse rows of small, circular pores, quincuncially disposed.

Dimensions.—Length of the shell (with five joints) 0.1; length of each joint (except the first) 0.02, breadth 0.05.

Habitat.—Fossil in Tertiary rocks of Sicily; Caltanisetta (Ehrenberg), Grotte (Stöhr).

10. Lithomitra seriolata, Haeckel.

Eucyrtidium seriolatum, Ehrenberg, 1858, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 33. Lithocampe seriolata, Haeckel, Monogr. d. Radiol., p. 316.

Shell subcylindrical, smooth, with four to six sharp strictures. Cephalis small, hemispherical. Thorax conical. Abdomen cylindrical, with three to five different joints of alternate sizes. Small circular pores in transverse rows; three or four rows in the third and fifth joints, seven or eight rows in the second, fourth, and sixth joints.

Dimensions.—Length of the shell (with six joints) 0.1; length of the second and fourth joints 0.03, of the third and fifth joints 0.015.

Habitat.—Mediterranean, Crete (Ehrenberg), Corfu (Haeckel).

11. Lithomitra hyperborea, Haeckel.

Eucyrtidium hyperboreum, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii., pl. i. fig. 10. Lithocampe hyperborea, Haeckel, 1862, Monogr. d. Radiol., p. 315.

Shell cylindrical, with prominent longitudinal ribs and six deep strictures. Cephalis hemispherical. On each joint three to four transverse rows of small, obsolete pores. Each joint is about twice as broad as long.

Dimensions.—Length of the shell (with six joints) 0.12; length of each joint 0.02, breadth 0.04.

Habitat.—Arctic and Northern Pacific, Kamtschatka (Bailey).

12. Lithomitra australis, Haeckel.

Lithocampe australis, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 187.

Lithocampe australis, Haeckel, 1862, Monogr. d. Radiol., p. 315.

Eucyrtidium australe, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 43; Mikrogeol., 1854, Taf. xxxv., A 21, fig. 18.

Shell subcylindrical, smooth, with five deep strictures. The two middle joints somewhat larger than the two proximal and the two distal joints. Pores small, circular, in regular, transverse rows; two rows in the first and the sixth joints, five rows in the second and the fifth, seven or eight rows in the third and fourth joints. The two latter are twice as broad as long.

Dimensions.—Length of the shell (with six joints) 0.14; length of the four smaller joints 0.017, of the two larger joints 0.035; breadth 0.06.

Habitat.—Antarctic Sea (lat. 78° 10′ S., long. 162° W.) Ross.

13. Lithomitra eminens, Haeckel.

Lithocampe eminens, Stöhr, 1880, Palæontogr., vol. xxvi. p. 102, Taf. iv. fig. 2.

Shell subcylindrical, rough, with seven slight strictures. The two or three middle joints half as long as the two preceding and the two following joints. Cephalis small, subspherical. Pores small, in subregular, transverse rows, on the fifth and sixth joints only two rows, on the second, third, seventh, and eighth joints four to five rows.

Dimensions.—Length of the shell (with eight joints) 0.27; length of the fifth and sixth joints 0.17, of the others 0.03 to 0.04; breadth 0.08.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte (Stöhr).

14. Lithomitra infundibulum, n. sp. (Pl. 79, fig. 5).

Shell in the upper half subconical, in the lower half subcylindrical, rough, with four slight strictures. Cephalis hemispherical. Thorax conical. Abdomen subcylindrical, three-jointed. Pores of the second, third, and fourth joints funnel-shaped, with very small inner, and larger double-contoured outer aperture; on the thorax twelve transverse rows, on the third and fourth joints five rows. Fifth joint with irregular, polygonal pores.

Dimensions.—Length of the shell (with five joints) 0.2; length of the thorax 0.06, breadth 0.08; length of each abdominal joint 0.04, breadth 0.08.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 647. Eucyrtidium,^[152] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Stichocorida (vel Stichocyrtida eradiate aperta) with ovate or spindle-shaped shell, the mouth of which is constricted, but not prolonged into a tube. Cephalis with a solid horn.

The genus Eucyrtidium (as here stated in the definition) and the three following nearly allied genera differ from the preceding Stichocorida in the more or less constricted mouth, and the consequent ovate or spindle-form of the multiarticulate shell. The middle joints of the latter are broader than the upper and the lower joints. In the earlier definition given in my Monograph (1862, pp. 312 to 320), the genus had a much wider sense; but the very large number of species since detected requires a more strict definition. Ehrenberg confounded in his genus Eucyrtidium a large number of very different Cyrtoidea. In his last works (1872, 1875) he described not less than one hundred and eleven species, fifty-five fossil and fifty-six living (eight fossil species being yet living). But, in reality, these one hundred and three species belong to twenty or twenty-two very different genera of Cyrtoidea.

Subgenus 1. Eucyrtis, Haeckel, 1881, Prodromus, p. 438.

Definition.—All joints of the shell nearly of the same length (excepting often the first). Surface smooth or rough, without spines.

1. Eucyrtidium acuminatum, Ehrenberg.

Eucyrtidium acuminatum, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 43; Mikrogeol., 1854, Taf. xii. fig. 27.

Eucyrtidium acuminatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 104, Taf. iv. fig. 6.

Eucyrtidium acuminatum, Haeckel, 1862, Monogr. d. Radiol., p. 326.

Lithocampe acuminata, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 84.

Shell smooth, slender, nearly spindle-shaped, without external strictures, but with eight to nine internal septal rings. All joints (except the first) nearly of the same length (or the upper somewhat longer). The fifth joint is the broadest. Cephalis small, subspherical, with a short, conical horn. Pores very small and numerous, regular, hexagonal, four to six on the length of each joint.

Dimensions.—Length of the shell (with eight joints) 0.14; length of each joint about 0.02; greatest breadth, in the fifth joint, 0.07.

Habitat.—Fossil in Tertiary rocks of Sicily (Caltanisetta, Grotte, &c.).

2. Eucyrtidium tropezianum, Haeckel.

Lithocampe tropeziana, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 42, Taf. vii. figs. 4, 5, 6. Lithocampe tropeziana, Haeckel, 1862, Monogr. d. Radiol., p. 326.

Shell smooth, slender, nearly spindle-shaped, without external strictures, but with seven or eight internal septal rings. All joints of the same length. The fifth and sixth joints are the broadest. Cephalis hemispherical, with a pyramidal horn of the same length. Pores very small and numerous, regular, circular, hexagonally framed, five to six in the length of each joint. (Very near to the preceding species, but more regular, and with different pores.)

Dimensions.—Length of the shell (with eight joints) 0.16, length of each joint 0.02; greatest breadth (in the fifth joint) 0.07.

Habitat.—Mediterranean, French shore, St. Tropez (J. Müller), surface.

3. Eucyrtidium hexagonatum, n. sp. (Pl. 80, fig. 11).

Shell smooth, ovate, with six to seven internal septal rings. All joints (except the first) nearly of the same length; the sixth joint is the broadest. The seventh and eighth joints (broken off in the specimen figured) gradually decrease toward the constricted mouth, which is as broad as the septum between the third and fourth joints. Cephalis and thorax together pear-shaped, with circular pores, sharp lumbar stricture, and a stout, pyramidal horn of the same length. The five or six abdominal joints with regular, hexagonal pores, six or seven in course of the length of each joint.

Dimensions.—Length of the shell (with eight joints) 0.2, length of each joint 0.025 to 0.03; greatest breadth (in the sixth joint) 0.1.

Habitat.—Central Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms.

4. Eucyrtidium fusiforme, n. sp.

Shell smooth, slender, spindle-shaped, without external strictures, but with ten to twelve internal septal rings. All joints of the same length; the sixth joint is the broadest. Cephalis conical, with a pyramidal horn of the same length. Pores regular, circular, four or five in course of the length of each joint. (Differs from all other species of the genus in the regular, slender, spindle form; the constricted mouth of the last joint is half as broad as the sixth joint.)

Dimensions.—Length of the shell (with twelve joints) 0.24, length of each joint 0.02; greatest breadth (on the sixth joint) 0.06, of the mouth 0.03.

Habitat.—Indian Ocean, Maldive Islands (Haeckel, 1882), surface.

5. Eucyrtidium doliolum, n. sp.

Shell smooth, barrel-shaped, or nearly spindle-shaped, with eight or nine distinct strictures. All joints (except the first) of the same length; the fourth joint is the broadest. Cephalis small, subspherical, with two short, divergent, conical horns. Pores regular, circular, hexagonally framed, three to four in course of the length of each joint.

Dimensions.—Length of the shell (with ten joints) 0.2, length of each joint 0.022; greatest breadth (in the fourth joint) 0.08.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

Subgenus 2. Stichocyrtis, Haeckel, 1881, Prodromus, p. 438.

Definition.—All joints of the shell nearly of the same length (excepting often the first). Surface spiny.

6. Eucyrtidium spinosum, n. sp.

Shell spiny, slender, ovate, without external strictures, but with seven or eight internal septal rings. Conical spines of different lengths are scattered over the whole surface. All joints have nearly the same length; the sixth is the broadest. Cephalis conical, with one large and two or three smaller conical horns. Mouth constricted, half as broad as the shell. Pores irregular, roundish, double-edged, three to four on the length of each joint.

Dimensions.—Length of the shell (with eight joints) 0.16, length of each joint 0.02; greatest breadth (on the sixth joint) 0.06.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

7. Eucyrtidium chrysalidium, n. sp.

Shell spiny, spindle-shaped, with four to five slight strictures, above each stricture a circle or girdle of conical spines (as in the similar Cyrtophormis cingulata, Pl. 78, fig. 18). All joints (except the first) have the same length. Cephalis subspherical, with a bunch of divergent spines. Mouth constricted, only one-third as broad as the third joint, which is the broadest. Pores subregular, circular, four to five on the length of each joint.

Dimensions.—Length of the shell (with six joints) 0.18, length of each joint 0.032; greatest breadth 0.08.

Habitat.—South Pacific, Station 302, depth 1450 fathoms.

Subgenus 3. Artocyrtis, Haeckel.

Definition.—Joints of the shell of very different lengths. Surface smooth or rough, without spines.

8. Eucyrtidium profundissimum, Ehrenberg.

Eucyrtidium profundissimum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. vii. fig. 12.

Shell smooth, campanulate, ovate, with three internal septal rings. Four joints of different lengths. Cephalis subspherical, with a small bristle-shaped horn. Thorax campanulate, nearly twice as long as each of the two following joints, which are nearly equal in breadth. Terminal mouth wide open, little constricted. Pores very small and numerous, regular, hexagonal.

Dimensions.—Length of the shell (with four joints) 0.12; length of the thorax 0.05, breadth 0.07.

Habitat.—Pacific; many Stations (Stations 206, 225, 253, 265, &c.), in depths between 2000 and 4000 fathoms.

9. Eucyrtidium anthophorum, Haeckel.

Thyrsocyrtis anthophora, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 84, Taf. xii. fig. 9.

Shell smooth, slender, ovate, with three slight strictures. Four joints of different lengths. Cephalis subspherical, with a stout, club-shaped, spinulate or branched horn of the same length. Second campanulate and third subcylindrical joint about equal in size. Fourth joint only half as long, with slightly constricted mouth (broken off in Ehrenberg's figure). Pores small and numerous, regular, circular, quincuncial.

Dimensions.—Length of the shell (with four joints) 0.12; length of the second and of the third joints 0.04, breadth 0.05 to 0.06.

Habitat.—Fossil in Barbados.

10. Eucyrtidium hertwigii, n. sp. (Pl. 80, fig. 12).

Shell smooth, ovate, truncate, with three distinct strictures. Four joints of different lengths. Cephalis campanulate, with an internal rod-cross, and a stout pyramidal horn of the same length. Second joint campanulate. Third joint larger, subcylindrical, with a variable number of irregular, longitudinal ribs, some of which are prolonged into the second and fourth joints. The latter is only half as long, and slightly constricted towards the mouth. Pores small and numerous, subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.22. Length of the single joints, a 0.03, b 0.06, c 0.08, d 0.05; breadth, a 0.03, b 0.1, c 0.12, d 0.11.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

11. Eucyrtidium lagena, Haeckel.

Eucyrtidium lagena, Haeckel, 1862, Monogr. d. Radiol., p. 325, Taf. iv. fig. 11. Lithocampe lagena, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 839.

Shell smooth, bottle-shaped, with three distinct strictures. Four joints of different sizes. Cephalis small, spherical, with a bristle-shaped horn of the same length. Second joint conical, third subcylindrical, fourth inflated, with slightly constricted mouth; their lengths about equal. Pores subregular, hexagonal, large, with thin bars.

Dimensions.—Length of the shell (with four joints) 0.16; length of each of the three lower joints about 0.05, breadth 0.05 to 0.064.

Habitat.—Mediterranean (Messina).

12. Eucyrtidium teuscheri, n. sp. (Pl. 77, fig. 5).

Shell smooth, bottle-shaped, with three distinct strictures. Four joints of different lengths. The third joint four times as long as each of the two first joints, and longer than the fourth, which is little constricted towards the mouth. The greatest breadth is in the middle of the shell. Cephalis hemispherical, with a small, conical horn of the same length. Pores large, circular, of variable sizes. Dedicated to Dr. Reinhold Teuscher.

Dimensions.—Length of the shell (with four joints) 0.16. Length of the single joints, a 0.015, b 0.02, c 0.07, d 0.055; breadth, a 0.03, b 0.05, c 0.08, d 0.06.

Habitat.—Central Pacific, Stations 266 to 274, depth 2350 to 2925 fathoms.

13. Eucyrtidium bütschlii, n. sp. (Pl. 77, fig. 7).

Shell rough, slender, ovate, truncate, with three distinct strictures. Four joints of different lengths; the third is the largest, inflated, subspherical. Fourth joint subcylindrical, little constricted towards the truncate mouth. Cephalis hemispherical, with a small, conical horn. Pores circular, much larger in the third joint than in the three others.

Dimensions.—Length of the shell (with four joints) 0.16. Length of the single joints, a 0.02, b 0.03, c 0.06, d 0.05; breadth, a 0.03, b 0.07, c 0.09, d 0.07.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

14. Eucyrtidium galatheæ, Ehrenberg.

Eucyrtidium galatheæ, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 242.

Shell smooth, campanulate, with three deep strictures. Four joints of different lengths; the fourth joint is the broadest, twice as long as the third and the second, three times as long as the hemispherical cephalis, which bears a stout, pyramidal, oblique horn of twice the length. Mouth little constricted. Pores regular, circular, in transverse rows, three rows in each of the three first joints, five or six rows in the last joint.

Dimensions.—Length of the shell (with four joints) 0.12; length of the fourth joint 0.05, breadth 0.07.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

15. Eucyrtidium galea, Haeckel.

Eucyrtidium galea, Haeckel, 1862, Monogr. d. Radiol., p. 324, Taf. vii. figs. 8-10. Lithocampe galea, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 838.

Shell smooth, helmet-shaped, with four sharp strictures. Five joints of different lengths. Cephalis small, spherical, with a thin pyramidal horn of the same length. Second joint conical, about as long as the third, longer than the fourth and the fifth joints. The third joint is the broadest. Pores regular, circular, small and numerous.

Dimensions.—Length of the shell (with five joints) 0.18; length of the second and the third joints 0.05, of the fourth 0.03; breadth 0.08 to 0.1.

Habitat.—Mediterranean (Messina), surface.

16. Eucyrtidium eruca, Ehrenberg.

Eucyrtidium eruca, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. x. fig. 13.

Shell smooth, slender, ovate, or nearly spindle-shaped, with four sharp strictures. Five joints of different lengths, the third and fourth nearly equal, twice as long as the fifth, one and a half times as long as the second; the fourth joint is the broadest. Mouth little constricted. Cephalis subspherical, with a small, conical horn. Pores small and numerous, subregular, circular.

Dimensions.—Length of the shell (with five joints) 0.12 to 0.14; length of the third and the fourth joints, 0.03 to 0.04, breadth 0.04 to 0.05.

Habitat.—Cosmopolitan; Atlantic, Pacific, in different depths; also fossil in Barbados and Sicily.

17. Eucyrtidium montiparum, Ehrenberg.

Eucyrtidium montiparum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 11.

Shell rough, nearly spindle-shaped, with five deep strictures. Six joints of different lengths, the third and fourth nearly equal, longer than the fifth and the sixth joints; the fourth joint is the broadest. Mouth slightly constricted. Cephalis very small, hemispherical, hyaline, with a short, conical horn. Pores subregular, circular, twice as broad as in the similar smaller preceding species.

Dimensions.—Length of the shell (with six joints) 0.2; length of the third and the fourth joints 0.05, breadth 0.07 to 0.08.

Habitat.—Fossil in Barbados.

18. Eucyrtidium cienkowskii, n. sp. (Pl. 80, fig. 9).

Shell smooth, subconical, with five distinct strictures. Six joints of different lengths; the third joint conical, one and a half to two times as long as each of the other joints; the fifth joint is the broadest. Mouth wide, very slightly constricted. Cephalis hemispherical, with an oblique pyramidal horn of the same length. Pores regular, circular, in dense transverse rows; five to six rows in each of the three last joints, eight to nine rows in the third joint.

Dimensions.—Length of the shell (with six joints) 0.16, length of the third joint 0.04, of each following joint 0.02; greatest breadth (in the fifth joint) 0.08.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

19. Eucyrtidium elongatum, Stöhr.

Eucyrtidium elongatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 105, Taf. iv. fig. 10.

Shell rough, slender, nearly spindle-shaped, variable in size and form, with six to seven distinct strictures. Seven to eight joints of different lengths, often alternately longer and shorter. The second and the last joints are the longest, the third is the broadest. Mouth slightly constricted (broken off in Stöhr's figure). Cephalis small, subspherical, with a small, oblique, curved horn. Pores irregular.

Dimensions.—Length of the shell (with seven joints) 0.2; length of the single joints, between 0.02 and 0.04, breadth 0.06 to 0.08.

Habitat.—Fossil in Sicily (Grotte, Caltanisetta).

20. Eucyrtidium stöhrii, n. sp.

Shell smooth, spindle-shaped, gradually diminishing towards both ends, with eight to ten distinct strictures. Nine to eleven joints of different lengths; the two or three middle joints—fifth, sixth, and seventh—longer and broader than the other joints; the broadest is the fifth joint, which is twice to three times as long as the first and last joints. Cephalis subspherical, with a conical horn of the same length. Terminal mouth strongly constricted, one-half or one-third as broad as the fifth joint. Pores small, regular, circular.

Dimensions.—Length of the shell (with ten joints) 0.22; length of the largest (fifth joint) 0.03, breadth 0.09.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

21. Eucyrtidium scalarium, n. sp.

Shell smooth, slender, ovate, with nine to ten deep strictures, and ten to eleven separate step-like joints of different lengths. The sixth joint is the longest, twice as long as the fourth, and three times as long as the third and the last joint; the seventh and eighth joints are the broadest, one and a half times as broad as the wide mouth. Cephalis hemispherical, with a short pyramidal horn of the same length. Pores small and numerous, subregular, square, in regular transverse rows; six rows in the sixth joint, three rows in the last joint. (Somewhat similar to Spirocyrtis scalaris, Pl. 76, fig. 14, but ovate, not conical and not spiral.)

Dimensions.—Length of the shell (with eleven joints) 0.22, breadth 0.11; length of the last joint 0.01, of the sixth 0.03.

Habitat.—North Atlantic, Station 64, surface.

Subgenus 4. Acanthocyrtis, Haeckel, 1881, Prodromus, p. 437.

Definition.—Joints of the shell of very different lengths. Surface spiny.

22. Eucyrtidium tricinctum, n. sp. (Pl. 78, fig. 13).

Shell spiny, spindle-shaped, with three distinct strictures. Four joints of different lengths, the first and third half as long as the second and fourth; the third joint is the broadest, four times as broad as the strongly constricted mouth. Spines irregularly scattered over the lower half of the shell, increasing in size towards the mouth. Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.25. Length of the single joints, a 0.03, b 0.08, c 0.04, d 0.09; breadth (of the third joint) 0.1.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

23. Eucyrtidium armatum, n. sp. (Pl. 78, fig. 14).

Shell spiny, spindle-shaped, with three distinct strictures. Four joints of different lengths, the second and third joints of the same length, shorter than the fourth joint; the third joint is the broadest, four times as broad as the strongly constricted mouth. The latter, as well as the conical cephalis, is armed with an irregular bunch of strong conical spines, while numerous smaller spines are scattered over the whole surface. Pores irregular, roundish, double-contoured.

Dimensions.—Length of the shell (with four joints) 0.2. Length of the single joints, a 0.02, b 0.05, c 0.05, d 0.08; breadth (of the third joint) 0.1.

Habitat.—Western Tropical Pacific, Station 224, depth 1850 fathoms.

24. Eucyrtidium conostoma, n. sp. (Pl. 78, fig. 16).

Shell spiny, spindle-shaped, with four distinct strictures. Five joints of different lengths, having the proportion = 1 : 2 : 3 : 6 : 10. The fourth joint is the broadest, inflated, twice as broad as long. Cephalis small, with a conical horn of the same length. Fifth joint inversely conical, with a narrow mouth, broader than the cephalis. Short conical spines are scattered over the whole surface. Pores subregular, circular.

Dimensions.—Length of the shell (with five joints) 0.22. Length of the single joints, a 0.01, b 0.02, c 0.03, d 0.06, e 0.1; breadth (of the fourth joint) 0.09.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

25. Eucyrtidium ehrenbergii, n. sp. (Pl. 78, fig. 15).

Shell spiny, spindle-shaped, with four distinct strictures (the first and the fourth are by a mistake not distinctly figured). Five joints of different lengths, having the proportion = 2 : 3 : 4 : 2 : 5. The third joint is the broadest, twice as broad as long, and twice as broad as the constricted mouth. Whole surface covered with strong spines. Pores irregular, roundish.

Dimensions.—Length of the shell (with five joints) 0.16. Length of the single joints, a 0.02, b 0.03, c 0.04, d 0.02, e 0.05; breadth (in the third joint) 0.08.

Habitat.—Western Tropical Pacific, Station 220, depth 1100 fathoms.

26. Eucyrtidium ovatum, n. sp.

Shell spiny, inversely ovate, with five sharp strictures. Six joints of different lengths, having the proportion = 1 : 3 : 2 : 1 : 1 : 3. The third joint is the broadest, three times as broad as the constricted mouth. Cephalis with a stout pyramidal horn of the same length. Whole surface spiny. Pores irregular, roundish.

Dimensions.—Length of the shell (with six joints) 0.22. Length of the single joints, a 0.02, b 0.06, c 0.04, d 0.02, e 0.02, f 0.06; breadth (in the third joint) 0.11.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

Genus 648. Eusyringium,^[153] Haeckel, 1881, Prodromus, p. 437.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with ovate or spindle-shaped shell, the mouth of which is constricted, and prolonged into a terminal cylindrical tube. Cephalis with a solid horn.

The genus Eusyringium differs from the preceding closely allied genus Eucyrtidium in the peculiar formation of the last shell-joint, representing a narrow, cylindrical, fenestrated tube. It exhibits, therefore, to the latter the same relation as Theosyringium bears to Theocorys.

Subgenus 1. Eusyringartus, Haeckel.

Definition.—Shell with three strictures and four joints; the third joint is the largest, inflated, and much broader than the three others.

1. Eusyringium conosiphon, n. sp. (Pl. 78, fig. 10).

Shell with four joints, very thick-walled, rough. Cephalis hemispherical, with a very stout, smooth, three-sided pyramidal horn of the same length and breadth. Thorax hemispherical. Third joint subspherical, three times as long, and twice as broad as the thorax, and of the same length as the slender, inversely conical fourth joint. Pores in the three first joints subregular, circular, in the fourth joint irregular.

Dimensions.—Length of the shell (with four joints) 0.25. Length of the single joint a 0.02, b 0.03, c 0.1, d 0.1; breadth 0.12.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

2. Eusyringium pachysiphon, n. sp. (Pl. 78, fig. 11).

Shell with four joints, very thick-walled, rough. Cephalis conical, with a thick, dimpled, conical horn of the same length. Thorax hemispherical. Third joint inflated, subspherical, and fourth joint slender, inversely conical, as in the similar preceding species. Differs from the latter mainly in the form of the cephalic horn, and the cylindrical tube of the last joint. Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.3. Length of the single joints, a 0.03, b 0.03, c 0.12, d 0.12; breadth 0.15.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

3. Eusyringium macrosiphon, n. sp. (Pl. 78, fig. 12).

Shell with four joints, thick-walled, rough. Cephalis subspherical with a large, dimpled, conical horn of twice the length. The three following joints nearly of the same shape as in the two similar preceding species. It differs from these in the smaller size, the larger cephalic horn, and the longer tube of the fourth joint, which is twice as long as the subspherical third joint (in the figure the lower half is broken off). Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.3. Length of the single joints, a 0.03, b 0.03, c 0.08, d 0.16; breadth 0.09.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

4. Eusyringium leptosiphon, n. sp.

Shell with four joints, thin-walled, smooth. Cephalis subspherical, with a large, dimpled, slender, conical horn of three times the length. Thorax hemispherical. Third joint ovate, four times as long as the thorax, and of the same length as the thin, cylindrical tube of the fourth joint. Differs from the three preceding species in the more slender form and the thinness of the tube. Pores irregular, roundish.

Dimensions.—Length of the shell (with four joints) 0.33. Length of the single joints, a 0.02, b 0.03, c 0.13, d 0.15; breadth 0.1.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

5. Eusyringium sipho, Haeckel.

Eucyrtidium sipho, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 72, Taf. ix. fig. 2.

Shell with four joints, thick-walled, smooth. Cephalis subspherical, hyaline, without pores, with a thick, conical horn of twice the length. Thorax hemispherical. Third joint ovate, four times as long as the thorax, and of the same length as the thin, cylindrical fourth joint. Pores subregular, circular, in the fourth joint twice as broad as in the third, and three times as broad as in the second joint.

Dimensions.—Length of the shell (with four joints) 0.22. Length of the single joints, a 0.02, b 0.02, c 0.09, d 0.09; breadth 0.08.

Habitat.—Fossil in Barbados.

6. Eusyringium fistuligerum, Haeckel.

Eucyrtidium fistuligerum, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf ix. fig. 3.

Shell with four joints, thin-walled, smooth. Cephalis subspherical, with numerous very small pores, and a stout, pyramidal horn of the same length. Thorax hemispherical. Third joint subspherical, four times as long as the thorax, and of the same length as the slender, inversely conical or cylindrical, fourth joint. Pores irregular, roundish or circular, in the fourth joint twice as broad as in the two preceding joints.

Dimensions.—Length of the shell (with four joints) 0.2. Length of the single joints, a 0.02, b 0.02, c 0.08, d 0.08; breadth 0.09.

Habitat.—Fossil in Barbados.

Subgenus 2. Eusyringoma, Haeckel.

Definition.—Shell with four or more strictures, and five or more joints; the last joint is strongly constricted, and forms a narrow cylindrical tube.

7. Eusyringium lagenoides, Haeckel.

Eucyrtidium lagenoides, Stöhr, 1880, Palæontogr., vol. xxvi. p. 104, Taf. iv. fig. 8.

Shell with five joints, and four sharp strictures, nearly spindle-shaped. The third joint is twice as long as the second and the fourth. Cephalis small, cap-shaped, with a thin conical horn of the same length. The fifth joint is in Stöhr's figure broken off, but well conserved in a specimen from Caltanisetta, and represents a slender cylindrical tube, with few pores, half as long as the shell. Pores small, subregular, circular, quincuncial.

Dimensions.—Length of the shell (with five joints) 0.24, breadth 0.08; length of the third joint 0.06, of the second and the fourth 0.03, of the fifth 0.1; breadth of the basal tube 0.027.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte, Caltanisetta).

8. Eusyringium rhaphanus, Haeckel.

Eucyrtidium rhaphanus, Stöhr, 1880, Palæontogr., vol. xxvi. p. 106, Taf. iv. fig. 12.

Shell with six or seven joints of very different lengths, in the upper half campanulate, in the lower cylindrical. The second and the two last joints are the longest. Cephalis small, subspherical, with a short conical horn. The last joint is a narrow cylindrical tube of variable length, scarcely one-fourth as broad as the preceding joints. Pores in the upper joints regular, circular, in the lower irregular, roundish.

Dimensions.—Length of the shell (with seven joints) 0.2, breadth 0.1; length of the second and last joints 0.03 to 0.04; breadth of the basal tube 0.025.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte).

9. Eusyringium siphonostoma, n. sp. (Pl. 80, fig. 14).

Shell with eight joints, in the upper half slender, conical, in the lower half cylindrical. The single joints are separated by seven internal annular septa. The third and the seventh joints are the largest, twice as long as the three intercalated joints. Cephalis small, cap-shaped, with a conical horn of twice the length. The last joint (broken off in the specimen figured) is a narrow cylindrical tube, one-third as long and one-third as broad as the shell. Pores regular, circular, quincuncial.

Dimensions.—Length of the shell (with eight joints) 0.24, breadth 0.08; length of the single joints 0.02 to 0.04; breadth of the basal tube 0.03.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

10. Eusyringium cannostoma, n. sp. (Pl. 80, fig. 13).

Shell with nine or ten joints, slender ovate. The single joints are separated by eight or nine internal annular septa. The third joint is the longest, about twice or three times as long as each following joint. Cephalis hemispherical, with a curved, conical horn of the same length. The last joint is a narrow, cylindrical tube, about as long as the third joint, but only one-fourth as broad. Pores small, regular, circular, quincuncially disposed, and hexagonally framed.

Dimensions.—Length of the shell (with ten joints) 0.22, breadth 0.08; length of the third joint 0.04, of the other joints 0.01 to 0.02, of the basal tube 0.04; breadth of the latter 0.02.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Genus 649. Siphocampe,^[154] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with ovate or spindle-shaped shell, the mouth of which is constricted, but not prolonged into a tube. Cephalis with an oblique, open, apical tube.

The genus Siphocampe differs from the closely allied genera Lithocampe and Eucyrtidium in a very remarkable character, viz., the development of a hollow cylindrical tube on the cephalis. This probably serves for the emission of a bunch of pseudopodia. It has the same position and the same oblique direction on the cephalis as the solid apical horn of Eucyrtidium.

Subgenus 1. Siphocampula, Haeckel.

Definition.—All joints of the shell (excepting the first) are nearly equal in length.

1. Siphocampe tubulosa, n. sp. (Pl. 79, fig. 13).

Shell slender nearly spindle-shaped, with eight deep transverse strictures, and elegant longitudinal ribs. Nine joints slightly different in length and shape. Cephalis flat, cap-shaped, with three or four transverse rows of small pores, and a cylindrical, oblique tubule of twice the length. Each successive joint with a single transverse row of regular, circular pores at its lower edge, separated by divergent, longitudinal ribs. Last joint shorter, with a hyaline annular peristome of the same length. Mouth half as broad as the middle part of the shell.

Dimensions.—Length of the shell (with nine joints) 0.24; length of each joint (on an average) 0.02 to 0.03; breadth 0.08.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Siphocampe annulosa, n. sp. (Pl. 79, fig. 10).

Shell slender, subcylindrical, with nine slight transverse strictures, and interrupted longitudinal ribs. Ten joints nearly equal in length and shape, excepting the two first, which together form a hemispherical cephalothorax, with six to eight transverse rows of pores. Tubule of the cephalis short and wide, truncate, conical. Each of the eight abdominal joints with a single transverse row of small pores. Mouth constricted, without tubulose peristome, half as broad as the shell.

Dimensions.—Length of the shell (with ten joints) 0.18; length of each joint (on an average) 0.02, breadth 0.07.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

3. Siphocampe caminosa, n. sp. (Pl. 79, fig. 12).

Shell slender, subcylindrical, with six deep transverse strictures. Seven joints nearly equal in length and breadth. Cephalis hemispherical, with an oblique, cylindrical tubule of twice the length (in the figure the greater part is broken away). Small circular pores in transverse rows and in variable number; usually three rows in the first and the last joint, five rows in the fourth joint, four rows in each of the other joints. Mouth constricted, with a short tubulose peristome, only one-third as broad as the shell.

Dimensions.—Length of the shell (with seven joints) 0.18; length of each joint (on an average) 0.025, breadth 0.055.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

4. Siphocampe erucosa, n. sp. (Pl. 79, fig. 11).

Shell slender, nearly spindle-shaped, with five slight transverse strictures. Six joints nearly equal in length. The two first joints are united, and form together a hemispherical cephalothorax, with a short, oblique, cylindrical tubule. Pores regular, circular, double-contoured, in regular, transverse rows; two rows in the first and the last joints, four rows in each of the four middle joints. Mouth constricted, without peristome, only one-third as broad as the shell.

Dimensions.—Length of the shell (with six joints) 0.14; length of each joint (on an average) 0.02, breadth 0.07.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

Subgenus 2. Siphocampium, Haeckel, 1881, Prodromus, p. 437.

Definition.—The joints of the shell are very different in length.

5. Siphocampe quadrantalis, n. sp.

Shell nearly spindle-shaped, with three deep strictures. Four joints of very different lengths. Cephalis subspherical with an oblique cylindrical tubule of twice the length, and with few small pores. Thorax ovate, half as long as the shell, with twelve transverse rows of small pores. Abdomen with two short joints, each of which has two transverse rows of pores. Mouth constricted, one-third as broad as the thorax.

Dimensions.—Length of the shell (with four joints) 0.18; length of the thorax 0.1, breadth 0.08.

Habitat.—Western Tropical Pacific; North Coast of New Guinea, Station 220, depth 1100 fathoms.

6. Siphocampe spiralis, n. sp. (Pl. 79, fig. 14).

Shell nearly spindle-shaped, with eight slight strictures. Nine joints of very different lengths. Cephalis subspherical, with an oblique cylindrical tubule of the same length, and numerous small pores. Thorax conical, one-fourth as long as the shell, with eight transverse rows of small pores. Abdomen with numerous prominent, spirally convoluted ribs, and spiral rows of pores between them. The first abdominal joint is from two to three times as long as each of the six following joints. Abdominal pores larger, roundish, disposed in eleven transverse rows. Four rows in the first abdominal joint, one row in each of the five following, and two rows in the last joint. Mouth slightly constricted, two-thirds as broad as the shell.

Dimensions.—Length of the shell (with nine joints) 0.17, cephalis 0.02, thorax 0.04, abdomen 0.11; breadth 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms; also fossil in Barbados.

Genus 650. Lithocampe,^[155] Ehrenberg, 1838, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 128 (sensu emendato).

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with ovate or spindle-shaped shell, the mouth of which is constricted, but not prolonged into a tube. Cephalis without horn and tube.

The genus Lithocampe is the oldest of all "Polycystina," being founded by Ehrenberg in 1838 upon Lithocampe radicula. Afterwards numerous other species, which belong to very different genera, were described by him. In 1862 I attempted to give a more strict definition of this genus in my Monograph (p. 312 to 315), and separated it from the closely allied and often confounded Eucyrtidium by the absence of a cephalic horn. The great number of species afterwards discovered leads to the stricter definition given above.

Subgenus 1. Lithocampula, Haeckel.

Definition.—All joints of the shell (except often the first) are equal or nearly equal in length.

1. Lithocampe eupora, Haeckel.

Eucyrtidium euporum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 291, Taf. iv. fig. 30.

Shell smooth, ovate or subconical, with three deep strictures. Four joints equal in length, gradually increasing in breadth, each with three transverse rows of regular, circular, hexagonally-framed pores; the fourth joint is the broadest. Mouth little constricted, of the same breadth as the third joint.

Dimensions.—Length of the shell (with four joints) 0.08; length of each joint 0.02, greatest breadth 0.06.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms; North Atlantic, depth 3600 fathoms (Morse).

2. Lithocampe platycephala, Haeckel.

Eucyrtidium platycephalum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, pp. 145, 293, Taf. iii. fig. 16.

Shell smooth, subconical or slenderly ovate, with three slight strictures. Four joints equal in length, slightly increasing in breadth towards the mouth. The hemispherical cephalis with longitudinal ribs and irregular pores, each of the three other joints with four transverse rows of regular, circular pores. Mouth strongly constricted, half as broad as the third and fourth joints.

Dimensions.—Length of the shell (with four joints) 0.12; length of each joint 0.03, greatest breadth 0.06.

Habitat.—North Atlantic, depth 3600 fathoms (Morse).

3. Lithocampe nereidum, Haeckel.

Lithocampe nereidum, Haeckel, 1862, Monogr. d. Radiol., p. 319. Eucyrtidium nereidum, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 242; Mikrogeol., Taf. xxxv. B, b, fig. 22.

Shell smooth, slenderly ovate, with four deep strictures. Five joints equal in length, the fourth being the broadest. Each joint with three transverse rows of small, regular, circular pores (sometimes in the fourth joint there are four rows). Mouth constricted, half as broad as the fourth joint. (In Ehrenberg's figure all five joints are delineated, but the greater part of the hemispherical cephalis is broken off.)

Dimensions.—Length of the shell (with five joints) 0.1, of each joint 0.02; breadth of the fourth joint 0.05.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

4. Lithocampe radicula, Ehrenberg.

Lithocampe radicula, Ehrenberg, 1838, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 130, Taf. iv. fig. 11.; Mikrogeol., 1854, Taf. xxii. fig. 23a.

Shell smooth, spindle-shaped, with five sharp strictures. Six joints equal in length, each with four transverse rows of regular, circular, double-edged pores. The third and fourth joints are the broadest, and equal. The constricted mouth is not broader than the hemispherical cephalis, scarcely one-fourth as broad as the third and the fourth joints. This remarkable species is the oldest known skeleton of a Radiolarian, a figure of it being given in 1838, loc. cit. (compare my Monograph, 1862, p. 3, 4, 331). But this figure of Ehrenberg is not quite accurate, and differs from other figures of the same species, which he afterwards (1854) published in his Mikrogeologie (loc. cit.). The best of these is fig. 23a in pl. xxii., and is identical with the typical form (common in Barbados), and according to this I have here framed my description. The sixth joint possesses a distinct (though small) terminal mouth; when this becomes closed, the species passes over into Stichocapsa radicula.

Dimensions.—Length of the shell (with six joints) 0.18, length of each joint (on an average) 0.03; breadth of the third and fourth joints 0.08, of the second and fifth 0.06, of the terminal mouth and the cephalis 0.03.

Habitat.—Fossil in Tertiary rocks of Barbados.

5. Lithocampe ventricosa, Haeckel.

Dictyomitra ventricosa, Stöhr, 1880, Palæontogr., vol. xxvi. p. 102, Taf. iii. fig. 25.

Shell ovate, with six slight strictures. Seven joints nearly equal in length, each with four (or sometimes three or five) transverse rows of small, regular, circular pores, in the last joint the pores are larger. The fourth and fifth joints are the broadest, and are twice as broad as the constricted mouth.

Dimensions.—Length of the shell (with seven joints) 0.13 to 0.14; length of each joint 0.017 to 0.02, greatest breadth 0.083, mouth 0.04.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte, Caltanisetta.

6. Lithocampe fusiformis, n. sp.

Shell smooth, spindle-shaped, decreasing uniformly towards the two blunt poles, with eight or nine sharp strictures, and nine or ten joints of equal lengths, each with four transverse rows of regular, hexagonal pores. The fourth and fifth joints are the broadest. The constricted mouth is twice as broad as the hemispherical cephalis, half as broad as the fourth joint.

Dimensions. —Length of the shell (with ten joints) 0.2, of each joint 0.02; breadth of the fourth joint 0.06, mouth 0.03.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subgenus 2. Lithocampium, Haeckel, 1881, Prodromus, p. 437.

Definition.—The joints of the shell are very different in length.

7. Lithocampe ovata, n. sp. (Pl. 77, fig. 1).

Shell smooth, urceolate or ovate, with three sharp strictures. Four joints of different lengths, having the proportion 1 : 2 : 2 : 6. The fourth joint is inflated and the broadest. The mouth is constricted, short, tubular, of the same breadth as the hemispherical cephalis. Pores small, circular, in regular transverse rows; four rows in the first, four in the second, two in the third, and five in the fourth joint. The middle stricture is crossed by longitudinal ribs.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.01, b 0.02, c 0.02, d 0.06; greatest breadth 0.055.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

8. Lithocampe aquilonaris, Haeckel.

Lithocampe aquilonaris, Haeckel, 1862, Monogr. d. Radiol., p. 317. Eucyrtidium aquilonare, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii. p. 4, pl. i. fig. 9.

Shell smooth, subconical, with three distinct strictures. Four joints of different lengths, having the proportion 3 : 1 : 3 : 4. The fourth joint is the broadest, suddenly constricted, with a short tubular mouth of half the breadth. Pores subregular, circular, in transverse rows; three rows in the first joint, two in the second, four in the third, and three in the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.03, b 0.01, c 0.03, d 0.04; breadth 0.06.

Habitat.—North Pacific, Kamtschatka (Bailey), Station 241, depth 2300 fathoms.

9. Lithocampe quadrarticulata, Haeckel.

Lithocampe quadrarticulata, Haeckel, 1862, Monogr. d. Radiol., p. 319. Eucyrtidium quadrarticulatum, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 299.

Shell smooth, spindle-shaped, with three deep strictures. Four joints of different lengths = 1 : 3 : 4 : 3. The third joint is the broadest, being twice as broad as the constricted mouth of the fourth joint. Pores small, regular, circular, in transverse rows; two being in the first, three in the second, four in the third, three in the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.015, b 0.03, c 0.04, d 0.025; greatest breadth 0.05.

Habitat.—North Atlantic (Greenland, depth 1600 fathoms, Ehrenberg), Station 64, surface.

10. Lithocampe multiseriata, Haeckel.

Eucyrtidium multiseriatum, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, page 293, Taf. vii. fig. 9.

Shell smooth, spindle-shaped, or slenderly ovate, with three sharp strictures. Four joints of different lengths = 3 : 4 : 5 : 10. The third and fourth joints nearly equal in breadth, and twice as broad as the hemispherical cephalis. The truncate mouth is slightly constricted. Pores very small and numerous, in regular transverse rows. Three or four rows in the first, five or six in the second, seven or eight in the third, and fifteen to twenty in the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.015, b 0.02, c 0.025, d 0.05; breadth 0.045.

Habitat.—Tropical Pacific (Philippine Sea, Ehrenberg), Stations 206, 224, 266, in various depths.

11. Lithocampe diploconus, n. sp. (Pl. 77, fig. 3).

Shell rough, doubly conical, with three distinct strictures. Four joints of different lengths = 2 : 5 : 5 : 8. The third joint is the broadest. The three first joints form together a broad cone, and the fourth an inverse truncate cone; the latter is distinguished by convergent longitudinal ribs. Pores regular, circular, alternating with the ribs in the fourth joint. Truncate mouth hyaline, half as broad as the third joint.

Dimensions.—Length of the shell (with four joints) 0.2. Length of the single joints, a 0.02, b 0.05, c 0.05, d 0.08; breadth (in the middle part) 0.1.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

12. Lithocampe diaphana, Haeckel.

Eucyrtidium diaphanum, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 309.

Shell smooth, hyaline, spindle-shaped, decreasing uniformly towards both poles, with three distinct strictures. Four joints of different lengths; the second and third equal in breadth, twice as broad and three times as long as the first and the fourth. Pores very small and scarce, in transverse interrupted rows, commonly two rows in the first, two or three in the second, three or four in the third, and only one in the last joint. Mouth constricted, two-thirds as broad as the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.13. Length of the single joints, a 0.015, b 0.05, c 0.05, d 0.015; breadth (in the middle part) 0.06, mouth 0.02.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms.

13. Lithocampe hispida, Haeckel.

Lithocampe hispida, Haeckel, 1862, Monogr. d. Radiol., p. 318. Eucyrtidium hispidum, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 298; Abhandl. d. k. Akad. d. Wiss. Berlin, 1872, p. 291, Taf. ii. fig. 19.

Shell thorny, slenderly ovate, or nearly spindle-shaped, with four sharp strictures. Five joints of different lengths = 3 : 3 : 4 : 6 : 4. The fourth joint is the broadest, and nearly twice as broad as the constricted mouth. Pores small, circular, separated by longitudinal, spiny ribs, regularly disposed in transverse rows; three rows in the first and second, four rows in the third and fifth, six rows in the fourth joint.

Dimensions.—Length of the shell (with five joints) 0.1. Length of the single joints, a 0.015, b 0.015, c 0.02, d 0.03, e 0.02; greatest breadth 0.05.

Habitat.—Arctic Ocean (in different depths), Ehrenberg.

14. Lithocampe tumidula, Haeckel.

Lithocampe tumidula, Haeckel, 1862, Monogr. d. Radiol., p. 318.

Eucyrtidium tumidulum, Bailey, 1856, Amer. Journ. Sci. and Arts, vol. xxii. p. 5, pl. i. fig. 11.

Eucyrtidium tumidulum, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 293, Taf. ii. fig. 12.

? Eucyrtidium increscens, Ehrenberg, 1861, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 299.

? Lithocampe increscens, Haeckel, 1862, Monogr. d. Radiol., p. 318.

Shell smooth, nearly spindle-shaped, with four sharp strictures, very similar to the preceding in size and form. It differs in the smooth surface, the absence of longitudinal ribs, and the unequal size of the pores, which form four transverse series in each joint, and are much larger in the broadest (fourth) joint. Proportion of the five joints = 2 : 2 : 3 : 5 : 4.

Dimensions.—Length of the shell (with five joints) 0.1. Length of the single joints, a 0.012, b 0.012, c 0.02, d 0.03, e 0.025; greatest breadth 0.05.

Habitat.—Cosmopolitan; Atlantic, Pacific; many stations, in different depths.

15. Lithocampe heteropora, Haeckel.

Lithocampe heteropora, Haeckel, 1862, Monogr. d. Radiol., p. 317. Eucyrtidium heteroporum, Ehrenberg, 1854, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 242.

Shell smooth, subconical, obtuse, with four distinct strictures. Five joints of different lengths = 2 : 4 : 3 : 3 : 2. The fourth joint is the broadest. Mouth slightly constricted. Pores regular, circular, in the second joint much larger than in the four others, disposed in transverse series; two rows in the first and fifth, three rows in the second, four rows in the third and fourth joints.

Dimensions.—Length of the shell (with five joints) 0.14. Length of the single joints, a 0.02, b 0.04, c 0.03, d 0.03, e 0.02; greatest breadth 0.07.

Habitat.—North Atlantic (depth 2000 fathoms, Ehrenberg), Canary Islands, surface, Haeckel.

16. Lithocampe meta, Stöhr.

Lithocampe meta, Stöhr, 1880, Palæontogr., vol. xxvi. p. 103, Taf. iv. fig. 4.

Shell rough, subconical, obtuse, with four slight strictures. Five joints of different lengths = 2 : 4 : 5 : 4 : 2. The fourth joint is the broadest, and three times as broad as the constricted mouth. Pores, small, regular, circular, quincuncially disposed, equal in size; two transverse rows in the first and fifth, five rows in the second and fourth, six rows in the third joint.

Dimensions.—Length of the shell (with five joints) 0.14. Length of the single joints, a 0.017, b 0.033, c 0.04, d 0.033, e 0.017; greatest breadth 0.083.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte (Stöhr), Caltanisetta (Haeckel).

17. Lithocampe urceolata, n. sp. (Pl. 77, fig. 2).

Shell rough, wide, urceolate, without external strictures, but with four internal septal rings (not visible in the figure), each of which contains an internal circle of horizontal pores. Five joints of different lengths = 2 : 3 : 6 : 4 : 2. The third joint is the broadest, and three times as broad as the constricted mouth. Pores of very different sizes, irregular, roundish, with prominent polygonal frames. A very remarkable species.

Dimensions.—Length of the shell (with five joints) 0.17. Length of the single joints, a 0.02, b 0.03, c 0.06, d 0.04, e 0.02; greatest breadth 0.13.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

18. Lithocampe clava, Ehrenberg.

Lithocampe clava, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. iv. fig. 2.

Shell smooth, club-shaped, or slenderly ovate, with five internal septal rings. Six joints of very different lengths = 5 : 2 : 3 : 4 : 5 : 18. The sixth joint is the broadest, and as long as the five others together. Pores small, circular, in the basal half of the last joint irregular and larger. Constricted mouth as broad as the subspherical, hyaline cephalis.

Dimensions.—Length of the shell (with six joints) 0.15. Length of the single joints, a 0.02, b 0.011, c 0.013, d 0.016, e 0.02, f 0.07.

Habitat.—Fossil in Barbados.

19. Lithocampe hexacola, n. sp. (Pl. 79, fig. 7).

Shell smooth, nearly spindle-shaped, without external strictures, but with five internal septal rings. Six joints of different lengths = 4 : 8 : 5 : 5 : 5 : 10. The fourth joint is the broadest, and four times as broad as the constricted mouth. Pores subregular hexagonal, or irregular polygonal, with thin bars.

Dimensions.—Length of the shell (with six joints) 0.18, greatest breadth 0.09. Length of the six joints, a 0.02, b 0.04, c, d, and e each 0.025, f 0.05.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

20. Lithocampe heptacola, n. sp. (Pl. 79, fig. 8).

Shell smooth, subcylindrical, constricted at both poles, with six distinct strictures. Seven joints of different lengths, the five abdominal joints nearly equal, each half as long as the hemispherical, vaulted thorax, and twice as long as the subspherical, small cephalis. Mouth constricted, with a short, tubular, hyaline peristome (like an eighth joint without pores), about one-third as broad as each of the four middle joints. Pores subregular hexagonal, or irregular polygonal, with thin bars.

Dimensions.—Length of the shell (with seven joints) 0.24, greatest breadth 0.09. Length of the cephalis 0.02, thorax 0.06, each of the four following joints 0.03, of the last joint 0.04.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

21. Lithocampe octocola, n. sp. (Pl. 79, fig. 6).

Shell smooth, subcylindrical, thick-walled, constricted at both poles, without distinct, external strictures, but with seven internal septal rings. Eight joints of different lengths; four joints (the second to the fifth) being about twice as long as the four others (the first and the three last). The constricted mouth only one-third as broad as the four middle joints. Pores small and numerous, subregular, circular.

Dimensions.—Length of the shell (with eight joints) 0.19, breadth 0.09. Length of the second to the fifth joints, each 0.03; length of the four other joints, each about 0.016.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

22. Lithocampe polycola, n. sp.

Shell smooth, subcylindrical, constricted at both poles, with twelve to fifteen distinct strictures. Fourteen to sixteen joints of different lengths. Cephalis flat, cap-shaped, hyaline, without pores. Thorax nearly hemispherical, with three transverse rows of small circular pores. Each following joint (each abdominal joint) only with a single row of small pores. The constricted mouth of the last joint only one-third as broad as the middle part of the shell. (Very similar to Lithomitra eruca, Pl. 79, fig. 3.)

Dimensions.—Length of the shell (with sixteen joints) 0.3, breadth 0.08. Length of the cephalis 0.02, thorax 0.06, each of the following joints 0.015, last joint 0.025.

Habitat.—Tropical Pacific, Station 224, depth 1850 fathoms.

Genus 651. Spirocyrtis,^[156] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with spirally-arranged constrictions on the shell. Cephalis with a horn.

The genus Spirocyrtis and the following closely allied genus Spirocampe differ from the other Stichocorida (and also from nearly all Cyrtoidea) in a very remarkable character. The annular constrictions of the multiarticulate shell and the corresponding internal annular septa are here not separated, and do not lie in parallel, transverse planes (as usually happens), but they are all or partly connected in the form of an ascending spiral, so that the joints are not perfectly separated. An irregularity or asymmetry of growth on the different sides of the shell is probably the cause of this strange, spiral structure.

Subgenus 1. Spirocyrtidium, Haeckel.

Definition.—Shell conical, gradually dilating towards the wide open terminal mouth.

1. Spirocyrtis scalaris, n. sp. (Pl. 76, fig. 14).

Shell conical, gradually dilating towards the wide open mouth, with ten to twelve spiral convolutions, which correspond to the same number of short and broad chambers or joints, gradually increasing in breadth; all joints form together a spirally winding staircase. The length or height of the single joints or stairs is about equal, and each bears four or five transverse rows of small, square pores. Cephalis flat, cap-shaped, with two or three short divergent horns.

Dimensions.—Length of the shell (with ten joints or turnings) 0.16, length of each joint (on an average) 0.016; breadth of the third joint 0.04, of the fifth joint 0.07, of the tenth joint 0.1.

Habitat.—Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms.

2. Spirocyrtis cornutella, n. sp. (Pl. 76, fig. 13).

Shell conical, gradually dilating towards the wide mouth, similar to the preceding, but differing in the curved axis, and the broader and shorter joints, each of which bears only two or three transverse rows of square pores. The turnings of the staircase are not so sharp, nor so distinct, as in the preceding species. Cephalis with a single short horn.

Dimensions.—Length of the shell (with eight joints) 0.1; breadth of the fourth joint 0.05, of the eighth joint 0.08.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

Subgenus 2. Spirocyrtoma, Haeckel.

Definition.—Shell ovate, or nearly spindle-shaped, more or less tapering towards the narrower, somewhat constricted mouth.

3. Spirocyrtis holospira, n. sp. (Pl. 76, fig. 16).

Shell subovate, twice as long as broad, without external strictures, but with an internal regularly descending spiral septum, which separates seven to nine broad joints of nearly equal lengths; the first and second joints together are conical, and about as long as each of the following joints. Cephalis small, hemispherical, with a thick pyramidal horn of the same length. The fifth joint is the broadest, the truncate mouth is slightly constricted (in the specimen figured it is broken off). Pores regular, circular, quincuncial.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1; length of each joint, about 0.03.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

4. Spirocyrtis hemispira, n. sp.

Shell slender, nearly spindle-shaped, three times as long as broad, without external strictures, but with ten to eleven internal septa. The five or six upper of these are perfectly separate, complete parallel rings; the five or six lower are spirally connected. The eleven or twelve joints gradually taper in length and breadth, from the broadest middle towards the two constricted ends of the shell. The middle (fifth or sixth) joint is the broadest, and is three to four times as broad as the constricted mouth. Cephalis small, hemispherical, with a conical horn of the same length. Pores regular, circular, hexagonally framed.

Dimensions.—Length of the shell (with twelve joints) 0.25, breadth 0.09; length of the middle joint 0.03.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

5. Spirocyrtis merospira, n. sp. (Pl. 76, fig. 15).

Shell ovate, with six to eight slight strictures, twice as long as broad. The three or four upper joints are perfectly separated by annular septa, the three or four lower joints connected by an internal spiral septum. The spiral line is often more or less irregular or interrupted (as is also the case in the specimen figured). Mouth rather wide. Pores small, subregular, circular. A rather variable species.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

6. Spirocyrtis diplospira, n. sp. (Pl. 76, fig. 17).

Shell slender, ovate, with seven to eight slight strictures. All eight or nine joints are connected by an internal double spiral septum, the first spiral beginning from the ventral side, the second from the dorsal side of the collar stricture. Length and breadth of the single joints rather variable and irregular; the broadest joint is commonly the fifth. Mouth more or less constricted. Pores subregular, circular. This remarkable species differs from all other Cyrtoidea by the double spiral septum of the joints.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.1.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 652. Spirocampe,^[157] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichocorida (vel Stichocyrtida eradiata aperta) with spirally arranged constrictions on the shell. Cephalis without horn.

The genus Spirocampe has the same peculiar spiral structure of the shell as the preceding Spirocyrtis, and differs from it only in the absence of a cephalic horn. It exhibits, therefore, the same relation to the latter as the similar Lithocampe bears to Eucyrtidium.

1. Spirocampe callispira, n. sp. (Pl. 76, fig. 11).

Shell ovate, smooth, with six joints, connected in the form of a complete winding staircase. All the windings are nearly at equal distances; each bears one row of large roundish pores, enclosed by two rows of smaller pores. Cephalis hemispherical, of about the same breadth as the constricted, short tubular mouth.

Dimensions.—Length of the shell (with six joints) 0.15, breadth 0.09; mouth 0.03 diameter.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

2. Spirocampe allospira, n. sp. (Pl. 76, fig. 12).

Shell subcylindrical, or nearly spindle-shaped, smooth, very thick-walled, with eight joints alternately longer and shorter, and connected in the form of an irregular spiral. The distance between the windings is very variable. Pores small, regular, circular. Cephalis hemispherical, of about the same size as the short tubular mouth.

Dimensions.—Length of the shell (with eight joints) 0.2, breadth 0.08; mouth 0.03 diameter.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

3. Spirocampe polyspira, n. sp.

Shell cylindrical, rough, with twelve joints nearly equal in length, connected in the form of a regular, complete spiral. All windings are at the same distance. Pores regular, circular, three rows on each turning. Cephalis flat, cap-shaped, half as broad as the slightly constricted, not tubular mouth.

Dimensions.—Length of the shell (with twelve joints) 0.24, breadth 0.07; mouth 0.05 diameter.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Subfamily 2. Stichocapsida, Haeckel, 1881, Prodromus, p. 439.

Definition.—Lithocampida with the terminal mouth of the shell fenestrated (vel Stichocyrtida eradiata clausa).

Genus 653. Cyrtocapsa,^[158] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichocapsida (vel Stichocyrtida eradiata clausa) with an apical horn on the cephalis, without basal terminal spine.

The genus Cyrtocapsa and the two following genera represent together the small subfamily of Stichocapsida, or of those Cyrtoidea in which the many-jointed shell bears no radial appendages, and the terminal mouth is closed by a lattice-plate. They have been derived from the Stichocorida by development of such a closing plate. Cyrtocapsa bears an apical horn on the cephalis, and may be derived therefore directly from Eucyrtidium.

Subgenus 1. Cyrtocapsella, Haeckel.

Definition.—Shell with three annular strictures (or internal septa) and four distinct joints.

1. Cyrtocapsa tetrapera, n. sp. (Pl. 78, fig. 5).

Shell rough, pear-shaped, with three deep strictures. The three first joints are of equal lengths, and each half as long as the hemispherical fourth joint. Cephalis subspherical, with an oblique conical horn of the same length. The third joint is the broadest, three times as broad as long. Pores regular, circular.

Dimensions.—Length of the shell (with four joints) 0.15, breadth 0.09; length of each of the three first joints 0.03, of the last 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Cyrtocapsa compacta, n. sp. (Pl. 77, fig. 8).

Eucyrtidium compactum, Haeckel, 1878, Atlas, loc. cit.

Shell rough, pear-shaped, with three slight strictures. The hemispherical cephalis bears a thick pyramidal spine of the same length, and is half as long as the second and the third joints, one-third as long as the hemispherical fourth joint. The third joint is the broadest, three times as broad as long. Pores subregular, circular. In the centre of the basal pole is one larger pore, the remnant of the constricted mouth of Eucyrtidium.

Dimensions.—Length of the shell (with four joints) 0.16, breadth 0.12. Length of the single joints, a 0.02, b 0.04, c 0.04, d 0.06.

Habitat.—Western Tropical Pacific, Station 206, depth 2100 fathoms.

3. Cyrtocapsa inflata, n. sp.

Shell spiny, pear-shaped, with three deep strictures. The inflated third joint is twice as long as the second and fourth joints, and three times as long as the hemispherical cephalis, which bears a large conical horn of three times the length. Fourth joint flat, vaulted, inversely cap-shaped. The third joint is the broadest, being twice as broad as long. Pores regular, circular, double-contoured.

Dimensions.—Length of the shell 0.14, breadth 0.11. Length of the single joints, a 0.02, b 0.03, c 0.06, d 0.03.

Habitat.—North Pacific, Station 244, depth 2900 fathoms.

4. Cyrtocapsa pyrum, n. sp. (Pl. 78, fig. 8).

Shell thorny, pear-shaped, without external strictures, but with three internal annular septa. Length of the four joints = 2 : 5 : 6 : 7. The fourth joint is the broadest, being about twice as broad as long, and hemispherical. The small subspherical cephalis bears a stout conical horn of the same length. Pores large, regular, circular.

Dimensions.—Length of the shell (with four joints) 0.2, breadth 0.12. Length of the single joints, a 0.02, b 0.05, c 0.06, d 0.07.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

5. Cyrtocapsa cornuta, n. sp. (Pl. 78, fig. 9).

Shell rough, very thick-walled, nearly pear-shaped, with three annular strictures; the second of which is very sharp, the first and third slight. Length of the four joints = 3 : 4 : 5 : 6. The third joint is the broadest, being about twice as broad as long; the fourth joint is hemispherical. Cephalis subspherical, with a large, conical, curved horn of twice the length. Pores regular, circular, hexagonally framed.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.12. Length of the single joints, a 0.03, b 0.04, c 0.05, d 0.06.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

6. Cyrtocapsa diploconus, n. sp. (Pl. 78, fig. 6).

Shell rough, doubly conical, with three annular septa. Length of the four joints = 3 : 4 : 4 : 8. The third joint is the broadest, two and a half times as broad as long; the fourth is inversely conical, acute. Cephalis hemispherical, with a pyramidal horn of the same length. Pores irregular, roundish.

Dimensions.—Length of the shell (with four joints) 0.19, breadth 0.1. Length of the single joints, a 0.03, b 0.04, c 0.04, d 0.08.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

7. Cyrtocapsa fusulus, n. sp. (Pl. 78, fig. 7).

Shell smooth, spindle-shaped, with three distinct strictures. Length of the four joints = 1 : 1 : 4 : 3. The third joint is the broadest, somewhat longer than broad. The fourth joint is inversely conical. Cephalis hemispherical, with a coronal of large, ovate pores, and a pyramidal, sulcate, oblique horn of twice the length. Pores regular, circular.

Dimensions.—Length of the shell (with four joints) 0.18, breadth 0.07. Length of the single joints, a 0.02, b 0.02, c 0.08, d 0.06.

Habitat.—South Pacific, Station 295, depth 1500 fathoms.

Subgenus 2. Cyrtocapsoma, Haeckel.

Definition.—Shell with four or more annular septa, and five or more joints.

8. Cyrtocapsa incrassata, Haeckel.

Eucyrtidium incrassatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 105, Taf. iv. fig. 9.

Shell rough, spindle-shaped, with four annular septa. Length of the five joints = 2 : 3 : 4 : 4 : 4. The third joint is the broadest, nearly three times as broad as long. The fourth joint is inversely conical, acute. Cephalis small, spherical, with two short, conical, divergent horns. Pores small, regular, circular.

Dimensions.—Length of the shell (with five joints) 0.17, breadth 0.11. Length of the single joints, a 0.015, b 0.035, c 0.04, d 0.04, e 0.04.

Habitat.—Fossil in Tertiary rocks of Sicily, Grotte.

9. Cyrtocapsa costata, n. sp.

Shell smooth, spindle-shaped, twice as long as broad, with numerous longitudinal ribs, and four annular septa. Length of the five joints = 1 : 4 : 3 : 2 : 8. The third joint is the broadest. Fourth joint inversely conical, acute. Cephalis small, hemispherical, with a small conical horn. Pores regular, circular.

Dimensions.—Length of the shell (with five joints) 0.18, breadth 0.09. Length of the single joints, a 0.01, b 0.04, c 0.03, d 0.02, e 0.08.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

10. Cyrtocapsa colatractus, n. sp.

Shell smooth, spindle-shaped, with eight internal annular septa (without external stricture). All nine joints are nearly equal in length, the first somewhat shorter, the last longer. The fourth joint is the broadest, four times as broad as long. Last joint inversely conical, blunt. Cephalis subspherical, with a conical horn of the same length. Pores small and numerous, regular, circular.

Dimensions.—Length of the shell (with nine joints) 0.22, breadth 0.1; length of the cephalis 0.015, of the last joint, 0.03, of each of the seven other joints, 0.022 to 0.028.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

11. Cyrtocapsa chrysalidium, n. sp. (Pl. 76, fig. 9).

Shell rough, nearly spindle-shaped, with seven distinct strictures. Length of the eight joints = 4 : 6 : 11 : 8 : 5 : 5 : 4 : 3. The third and fourth joints are the broadest. The last joint is small, inversely cap-shaped. Cephalis subspherical, with an oblique, dentate horn of the same length. Pores very numerous, subregular, circular.

Dimensions.—Length of the shell (with eight joints) 0.23, breadth 0.1. Length of the single joints, a 0.02, b 0.03, c 0.055, d 0.04, e 0.025, f 0.025, g 0.02, h 0.015.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

Genus 654. Stichocapsa,^[159] Haeckel, 1881, Prodromus, p. 439.

Definition.—Stichocapsida (vel Stichocyrtida eradiata clausa) without apical horn, and without basal spine.

The genus Stichocapsa differs from the preceding Cyrtocapsa in the absence of an apical horn, and bears therefore to it the same relation as Lithocampe does to Eucyrtidium. It may be derived either from Cyrtocapsa by loss of the horn, or from Eucyrtidium by closure of the terminal mouth.

1. Stichocapsa tetracola, n. sp. (Pl. 78, fig. 1).

Shell smooth, spindle-shaped, half as broad as long, with three slight strictures. Length of the four joints = 3 : 4 : 4 : 11. The fourth joint is the broadest, inversely conical, with acute basal pole. Pores subregularly square in the second and third joints, more irregular in the fourth joint.

Dimensions.—Length of the shell (with four joints) 0.11. Length of the single joints, a 0.015, b 0.02, c 0.02, d 0.055; breadth 0.055.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

2. Stichocapsa quadrigata, n. sp. (Pl. 78, fig. 3).

Shell smooth, pear-shaped, half as broad as long, with three deep strictures. Length of the four joints = 3 : 8 : 8 : 5. The second joint is the broadest. The fourth joint is scarcely larger than the hemispherical cephalis, inversely conical, with blunt basal pole. Pores subregular, square, in transverse rows, in the second and third joints of equal size, in the fourth smaller.

Dimensions.—Length of the shell (with four joints) 0.12. Length of the single joints, a 0.015, b 0.04, e 0.04, d 0.025; breadth 0.06.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

3. Stichocapsa tricincta, n. sp. (Pl. 78, fig. 2).

Shell smooth, spindle-shaped, twice as long as broad, with three deep strictures. Length of the four joints = 2 : 5 : 5 : 10. The third joint is the broadest. Fourth joint inversely conical, with acute basal pole. Cephalis small, subconical. Pores irregular, roundish, of very different sizes.

Dimensions.—Length of the shell 0.11. Length of the single joints, a 0.01, b 0.025, e 0.025, d 0.05; breadth 0.055.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms.

4. Stichocapsa subglobosa, n. sp.

Shell thorny, broad, pear-shaped, nearly spherical, almost as broad as long, with three internal septal rings. Length of the four joints = 1 : 2 : 7 : 2. Cephalis small, subspherical. Thorax flat, conical. Third joint very large, inflated, about twice as broad as the second and fourth joints. The latter is flat, cap-shaped, with rounded basal pole. Pores regular, circular, hexagonally framed, in the third joint twice as broad as in the second and fourth joints.

Dimensions.—Length of the shell 0.24. Length of the single joints, a 0.02, b 0.04, c 0.14, d 0.04; breadth 0.2.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

5. Stichocapsa compressa, Haeckel.

Lithocampe compressa, Stöhr, 1880, Palæontogr., vol. xxvi. p. 103, Taf. iv. fig. 5.

Shell rough, broad, pear-shaped, almost as broad as long, with three internal septal rings. Length of the four joints = 1 : 2 : 3 : 2. Cephalis very small, spherical. Thorax conical. The third joint is the broadest, strongly inflated. The fourth joint (in the figure of Stöhr broken off) is in a well preserved specimen inversely hemispherical, with rounded basal pole. Pores very small, regular, circular.

Dimensions.—Length of the shell 0.1. Length of the single joints, a 0.013, b 0.027, c 0.04, d 0.022; breadth 0.08.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte, Caltanisetta.

6. Stichocapsa pyriformis, n. sp.

Shell rough, pear-shaped, about twice as long as broad, with three internal septal rings. Length of the four joints = 2 : 5 : 2 : 9. Cephalis small, spherical, hyaline. Thorax conical. Third joint very short and broad; the fourth joint is the broadest, half as long as the shell, with an inversely hemispherical basal pole. Pores subregular, circular, small and numerous, larger in the basal third.

Dimensions.—Length of the shell 0.18. Length of the single joints, a 0.02, b 0.05, c 0.02, d 0.09; breadth 0.1.

Habitat.—Fossil in Barbados.

7. Stichocapsa monstrosa, n. sp. (Pl. 78, fig. 4).

Shell tuberculate, twice as long as broad, irregular, horn-shaped or inversely conical, with curved axis, and with three internal septal rings. Length of the four joints = 2 : 7 : 3 : 4. Cephalis subspherical, with small, circular pores. The thorax is the broadest joint, half as long as the shell. The fourth joint is small, inversely conical, with a blunt, curved, basal pole. Pores irregular, roundish, partly double-contoured.

Dimensions.—Length of the shell (with four joints) 0.16. Length of the single joints, a 0.02, b 0.07, c 0.03, d 0.04; breadth 0.08.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

8. Stichocapsa pentacola, n. sp. (Pl. 76, fig. 1).

Shell smooth, slender, pear-shaped, twice as long as broad, with four sharp strictures. Length of the five joints = 1 : 1 : 1 : 2 : 3. The three first joints are nearly equal in length, but increase in breadth. The fifth joint is the broadest, nearly spherical, with rounded basal pole. Pores irregular, roundish.

Dimensions.—Length of the shell (with five joints) 0.13. Length of the single joints, a 0.017, b 0.017, c 0.017, d 0.028, e 0.05; breadth 0.07.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

9. Stichocapsa hexacola, n. sp. (Pl. 76, fig. 2).

Shell rough, slender, pear-shaped, twice as long as broad, with five internal septal rings. The five first joints are nearly equal in length. The sixth joint is the broadest, half as long as the shell, with a rounded, hemispherical basal pole. Pores small and numerous, subregular, circular, larger in the inflated basal third.

Dimensions.—Length of the shell (with six joints) 0.2. Length of each of the first five joints 0.02, of the sixth joint 0.1; breadth 0.1.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms; also fossil in Barbados.

10. Stichocapsa compacta, n. sp. (Pl. 76, fig. 3).

Shell rough very thick-walled, slender, pear-shaped, twice as long as broad, without external stricture, but with eight internal septal rings. The eight first joints, gradually increasing in breadth, are nearly equal in length. The eighth joint is the broadest, and one-third as long as the shell, inversely hemispherical. Pores small, circular, in the last joint larger.

Dimensions.—Length of the shell (with nine joints) 0.25. Length of each of the eight first joints about 0.02, of the ninth joint 0.08; breadth 0.13.

Habitat.—Central Pacific, Station 268, depth 2900 fathoms; also fossil in Barbados.

11. Stichocapsa radicula, Haeckel.

Lithocampe radicula, Ehrenberg, 1838 (partim); Mikrogeol., 1854, Taf. xxii. fig. 23b.?

Shell smooth, spindle-shaped, decreasing from the broader middle towards the two rounded poles, with four or five slight strictures. All five or six joints nearly equal in length, the middle (third and fourth) are the broadest. Pores subregular, circular. (To this species those forms of Lithocampe radicula, Ehrenberg, must be referred, in which the basal opening is perfectly closed by lattice-work. The other forms in which the basal mouth remains open, and which are connected with the former by transitional forms, constitute the true type of the genus Lithocampe (page 1503).

Dimensions.—Length of the shell (with six joints) 0.12 to 0.15, breadth 0.06 to 0.07.

Habitat.—Fossil in Barbados.

12. Stichocapsa subligata, Haeckel.

Lithocampe subligata, Stöhr, 1880, Palæontogr., vol. xxvi. p. 102, Taf. iv. fig. 1.

Shell rough, subcylindrical, irregular, with seven slight strictures. All eight joints of slightly different lengths, the third joint is the broadest; the seventh joint is much broader than the sixth and the eighth joints. The latter is inversely hemispherical. Cephalis very small, spherical. Pores regular, circular, very small and numerous.

Dimensions.—Length of the shell (with eight joints) 0.24; length of the single joints (on an average) 0.025 to 0.035, breadth 0.08.

Habitat.—Fossil in Tertiary rocks of Sicily (Grotte).

13. Stichocapsa paniscus, n. sp. (Pl. 76, fig. 4).

Shell smooth, cylindrical, with a blunt, conical cephalis, and a hemispherical last joint, without external strictures, but with seven or eight internal septa. Eight or nine joints nearly equal in length, the second and the last somewhat longer. Pores circular, of unequal sizes.

Dimensions.—Length of the shell (with seven joints) 0.16; length of each joint (on an average) 0.02 to 0.03, breadth 0.07.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

14. Stichocapsa cylindrica, n. sp.

Shell rough, cylindrical, four times as long as broad, with hemispherical cephalis and last joint, without external stricture, but with ten or eleven internal septa. All eleven or twelve joints are nearly equal in length, and are three times as broad as long. Only the flat cephalis is shorter, and the vaulted last joint longer than each of the nine or ten other joints. Pores regular, circular.

Dimensions.—Length of the shell (with twelve joints) 0.24; length of each joint (on an average) 0.02, breadth 0.06.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms.

Genus 655. Artocapsa,^[160] Haeckel, 1881, Prodromus, p. 438.

Definition.—Stichocapsida (vel Stichocyrtida eradiata clausa) with an apical horn on the cephalis, and a basal terminal spine on the last joint.

The genus Artocapsa differs from Cyrtocapsa, its ancestral form, by the development of a vertical terminal spine, or a bunch of spines, on the base of the last joint, and bears therefore to it the same relation as Rhopalatractus does to Rhopalocanium.

1. Artocapsa fusiformis, n. sp. (Pl. 76, fig. 5).

Shell spindle-shaped, rough, with five slight strictures, decreasing uniformly from the broader middle towards both poles, with a strong, pyramidal, terminal spine at each pole. Length of the six joints = 2 : 5 : 3 : 3 : 2 : 5. Cephalis hemispherical, hyaline, without pores, its horn half as large as the basal spine. Pores small and numerous, subregular, circular.

Dimensions.—Length of the shell (with six joints) 0.2, breadth 0.09. Length of the single joints, a 0.02, b 0.05, c 0.03, d 0.03, e 0.02, f 0.05.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

2. Artocapsa spinosa, n. sp. (Pl. 76, fig. 10).

Shell spindle-shaped, spiny, with five distinct strictures. Length of the six joints = 2 : 3 : 2 : 5 : 4 : 4. The fourth joint is the broadest, and much larger than the five other joints. The first and the last joints are similar in size and form, hemispherical, armed with some larger, irregular, conical spines. Pores irregular, roundish, of variable sizes.

Dimensions.—Length of the shell (with six joints) 0.2, breadth 0.09. Length of the single joints, a 0.02, b 0.03, c 0.02, d 0.05, e 0.04, f 0.04.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

3. Artocapsa infraculeata, Haeckel.

Eucyrtidium infraculeatum, Stöhr, 1880, Palæontogr., vol. xxvi. p. 106, Taf. iv. fig. 13.

Shell subcylindrical, rough, with five annular septa. Length of the six joints = 2 : 3 : 4 : 4 : 4 : 3. The third, fourth, and fifth joints are nearly equal in length and breadth, whilst the second and sixth are cupola-shaped. The cephalis is very small, subspherical (regarded by Stöhr as a "large pore"), and bears a short conical horn. The last joint bears a bunch of basal spines.

Dimensions.—Length of the shell (with six joints) 0.2, breadth 0.09. Length of the cephalis 0.02, second and sixth joints 0.03, third, fourth, and fifth joints 0.04.

Habitat.—Fossil in Tertiary rocks of Sicily; Grotte (Stöhr), Caltanisetta (Haeckel).

4. Artocapsa quadricamera, n. sp.

Shell spindle-shaped, smooth, with three sharp strictures. Length of the four joints = 2 : 3 : 4 : 8. The third joint is the broadest. The fourth joint is inversely conical, nearly as long as the three other joints together, and bears a strong, conical, basal spine, of half the length. The cephalis is small, subspherical, and bears a conical horn of the same length. Pores subregular, circular.

Dimensions.—Length of the shell (with four joints) 0.17, breadth 0.08. Length of the single joints, a 0.02, b 0.03, c 0.04, d 0.08.

Habitat.—Fossil in Barbados.

5. Artocapsa armata, n. sp.

Shell slender, inversely ovate, spiny, with six deep strictures. Length of the seven joints = 2 : 4 : 6 : 5 : 4 : 3 : 2. The third joint is the broadest, inflated, and much larger than the four following, which gradually decrease in size. The small, hemispherical cephalis bears a stout pyramidal horn of twice the length. The last hemispherical joint is armed with a bunch of stout spines, one of which is much the larger, and as long as the third joint. Pores irregular, roundish.

Dimensions.—Length of the shell (with seven joints) 0.26, breadth 0.12. Length of the single joints, a 0.02, b 0.04, c 0.06, d 0.05, e 0.04, f 0.03, g 0.02.

Habitat.—Western Tropical Pacific, Station 225, depth 4575 fathoms.

6. Artocapsa octocamera, n. sp.

Shell subcylindrical, smooth, with seven internal annular septa. Five joints (the third to the seventh) are nearly equal in size, while the second and eighth are cupola-shaped, somewhat longer. The cephalis is smaller, with a conical horn of the same length. The last joint bears a bunch of divergent, conical spines, of different lengths. Pores small, regular, circular.

Dimensions.—Length of the shell (with eight joints) 0.16, breadth 0.08. Length of the cephalis 0.016, second and eighth joints 0.033, each of the five other joints 0.022.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

7. Artocapsa elegans, n. sp. (Pl. 76, fig. 8).

Shell spindle-shaped, smooth, with eight internal, broad, annular septa. The second and third joints are the largest, the fourth and fifth of medium size, while the cephalis and the four last joints are nearly equal in length, and much shorter. The third joint is the largest. The subspherical cephalis bears a bristle-shaped horn of the same length, while the last joint is armed with a bunch of conical spines. Pores small, in the upper half of the shell regular, hexagonal, in the lower half irregular.

Dimensions.—Length of the shell (with nine joints) 0.2, breadth 0.09. Length of the first and the four last joints, each 0.014; of the fourth and fifth, each 0.02; of the third 0.04, second 0.05.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

↑ Tripocalpis = Urn with three feet; τρίπους, καλπίς.
↑ Tripodonium = Shell with three feet.
↑ Tripterocalpis = Urn with three wings; τρίπτερος, καλπίς.
↑ Trissopilium = Small hat with three wings; τρίσσος, πίλιον.
↑ Archipilium = Primordial hat; ἀρχιπίλιον.
↑ Tripilidium = Small hat with three feet; τρία, πιλίδιον.
↑ Tripodiscium = Shell with three small feet; τρία, ποδίσκιον.
↑ Tridictyopus = Shell with three lattice-feet; τρία, δίκτυον, πούς.
↑ Euscenium = Nice small tent; εὖ, σκηνίον.
↑ Cladoscenium = Small tent with branched axis; κλαδός, σκηνίον.
↑ Archiscenium = Primordial tent; ἀρχί, σκηνίον.
↑ Pteroscenium = Small tent with wings; πτερόν, σκηνίον.
↑ Peridium = Small pouch; πηρίδιον.
↑ Archipera = Primordial pouch; ἀρχί, πήρα.
↑ Archibursa = Primordial bottle; ἀρχί, βύρσα.
↑ Bathropyramis = Pyramid with ladders; βάθρον, πυραμίς.
↑ Cinclopyramis = Lattice-pyramid; κιγκλίς, πυραμίς.
↑ Peripyramis = Pyramid with an envelope; περί, πυραμίς.
↑ Litharachnium = Spider-web of silex; λίθος, ἀράχνιον.
↑ Cladarachnium = Spider-web with branched threads; κλαδός, ἀράχνιον.
↑ Cystophormis = bladder-basket; κυστή, φορμίς.
↑ Haliphormis = Sea-basket; ἅλς, φορμίς.
↑ Archiphormis = Primordial-basket; ἀρχί, φορμίς.
↑ Halicalyptra = Sea-veil; ἅλς, καλύπτρα.
↑ Carpocanistrum = Small fruit-basket; καρπός, κανίστρον.
↑ Arachnocalpis = Urn enveloped by spider's web; ἀράχνη, καλπίς.
↑ Phænocalpis = Urceolate shell; φαῖνα, καλπίς.
↑ Phænoscenium = Tent-shaped shell; φαῖνα, σκηνίον.
↑ Calpophæna = Urceolate shell; καλπίς, φαῖνα.
↑ Archiphæna = Primordial shell; ἀρχί, φαῖνα.
↑ Cornutella = Small horn; diminutive of cornu.
↑ Cornutanna = Horn-shaped; Cornuta.
↑ Archicorys = Principal helm; ἀρχίκορυς.
↑ Cyrtocalpis = Basket-urn or wicker-pitcher; κύρτος, καλπίς.
↑ Mitrocalpis = Turban basket; μίτρα, καλπίς.
↑ Spongocyrtis = Spongy basket; σπόγγος, κυρτίς.
↑ Halicapsa = Sea-capsule; ἅλς, κάψα.
↑ Archicapsa = Primordial capsule; ἀρχίκαψα.
↑ Dictyophimus = Net goblet; δίκτυον, φιμός.
↑ Tripocyrtis = Basket with a tripod; τρίπος, κυρτίς.
↑ Sethopilium = Small fenestrated hat; σήθω, πίλιον.
↑ Lithomelissa = Stone bee; λίθος, μέλισσα.
↑ Psilomelissa = Smooth bee; ψιλός, μέλισσα.
↑ Spongomelissa = Spongy bee; σπόγγος, μέλισσα.
↑ Clathrocanium = Basket of network; κλῆθρα, κάνεον.
↑ Lamprodiscus = Splendid disk; λαμπρός, δίσκος.
↑ Lampromitra = Splendid turban; λαμπρός, μίτρα.
↑ Callimitra = Beautiful turban; κάλλὶς, μίτρα.
↑ Clathromitra = Lattice-turban; κλῆθρα, μίτρα.
↑ Clathrocorys = Lattice-helmet; κλῆθρα, κόρυς.
↑ Eucecryphalus = Nice net-cap, εὖ, κεκρύφαλος.
↑ Amphiplecta = Shell at both poles open, with framework around; ἀμφίπληκτα.
↑ Lychnocanium = Lantern-basket: λύχνος, κάνεον.
↑ Lychnodictyum = Lantern with network; λύχνος, δίκτυον.
↑ Sethopera = Sieve-pouch; σήθω, πήρα.
↑ Lithopera = Stone-pouch; λίθος, πήρα.
↑ Micromelissa = Small bee; μικρός, μέλισσα.
↑ Peromelissa = Pouch-bee; πήρα, μέλισσα.
↑ Sethomelissa = Sieve-bee; σήθω, μέλισσα.
↑ Tetrahedrina = Small tetrahedron; τετράεδρον.
↑ Sethochytris = Sieve-pot; σήθω, χυτρίς.
↑ Clathrolychnus = Fenestrated lantern; κλῆθρα, λύχνος.
↑ Sethophormis = Sieve-basket; σήθω, φορμίς.
↑ Sethamphora = Sieve-pitcher; σήθω, ἀμφορεύς.
↑ Sethopyramis = Sieve-pyramid; σήθω, πυραμίς.
↑ Plectopyramis = Woven pyramid; πλεκτός, πυραμίς.
↑ Spongopyramis = Spongy pyramid; σπόγγος, πυραμίς.
↑ Acanthocorys = Spiny Helmet; ἄκανθα, κόρυς.
↑ Arachnocorys = helmet with a cobweb; ἀράχνη, κόρυς.
↑ Anthocyrtoma = Flower-arch; ἄνθος, κύρτωμα.
↑ Anthocyrtis = Flower-basket; ἄνθος, κυρτίς.
↑ Anthocyrtium = Flower-basket; ἄνθος, κύρτιον.
↑ Anthocyrtidium = Small flower-basket; ἄνθος, κυρτίδιον.
↑ Carpocanium = Fruit-basket; καρπός, κάνεον.
↑ Sethophæna = Sieve-shell; σήθω, φαῖνα.
↑ Clistophæna = Closed shell; κλειστός, φαῖνα.
↑ Sethoconus = Sieve-cone; σήθω, κῶνος.
↑ Periarachnium = Shell enveloped by cobweb; περί, ἀράχνιον.
↑ Sethocephalus = Sieve-head; σήθω, κεφαλή.
↑ Sethocyrtis = Sieve-basket; σήθω, κυρτίς.
↑ Sethocorys = Sieve-helmet; σήθω, κόρυς.
↑ Lophophæna = Shell with a top-knot; λόφος, φαίνω.
↑ Dictyocephalus = Latticed head; δίκτυον, κεφαλή.
↑ Sethocapsa = Sieve-capsule; σήθω, κάψα.
↑ Dicolocapsa = Two-jointed capsule; δίκωλος, κάψα.
↑ Cryptocapsa = Hidden capsule; κρυπτός, κάψα.
↑ Pterocorys = Helmet with wings; πτερόν, κόρυς.
↑ Theopilium = Divine hat; θεός, πίλιον.
↑ Corocalyptra = Coif or hood of a girl; κόρη, κάλυπτρα.
↑ Dictyoceras = Reticulated horn; δίκτυον, κέρα.
↑ Pteropilium = Small hat with wings; πτερόν, πίλιον.
↑ Theopodium = Divine foot; θεός, πόδιον.
↑ Pterocanium = Basket with wings; πτερόν, κάνεον.
↑ Pterocodon = Bell with wings; πτερόν, κώδων.
↑ Dictyocodon = Net-bell; δίκτυον, κώδων.
↑ Pleuropodium = Shell with ribs and feet; πλεῦρα, πόδιον.
↑ Podocyrtis = Basket with feet; πούς, κυρτίς.
↑ Thyrsocyrtis = Basket with a thyrsus or apical rod; θύρσος, κυρτίς.
↑ Dictyopodium = Shell with latticed feet; δίκτυον, πόδιον.
↑ Lithornithium = Siliceous bird; λίθος, ὀρνίθιον.
↑ Sethornithium = Latticed bird; σήθω, ὀρνίθιον.
↑ Theopera = Divine pouch; θεός, πήρα.
↑ Rhopalocanium = Basket with clubs; ῥόπαλον, κάνεον.
↑ Rhopalatractus = Spindle with clubs; ῥόπαλον, ἄτρακτος.
↑ Lithochytris = Pot of silex; λίθος, χυτρίς.
↑ Theophormis = Divine basket; θεός, φορμίς.
↑ Phormocyrtis = Plaited basket; φορμός, κυρτίς.
↑ Alacorys = Wing-helmet.
↑ Cycladophora = Bearing a female robe; κυκλάς, φόρος.
↑ Calocyclas = Beautiful female robe; καλός, κυκλάς.
↑ Clathrocyclas = Fenestrated female robe; κλῆθρα, κυκλάς.
↑ Lamprocyclas = Splendid female robe; λαμπρός, κυκλάς.
↑ Diplocyclas = Female robe with a double girdle; δίπλόος, κυκλάς.
↑ Hexalatractus = Spindle with six wings; ἕξαλα, ἄτρακτος.
↑ Theophæna = Divine shell; θεός, φαῖνα.
↑ Theocalyptra = Divine veil; θεός, καλύπτρα.
↑ Cecryphalium = Net-cap; κεκρυφάλιον.
↑ Theoconus = Divine cone; θεός, κῶνος.
↑ Lophoconus = Cone with a crest; λόφος, κῶνος.
↑ Theocyrtis = Divine basket; θεός, κυρτίς.
↑ Theosyringium = Divine tube; θεός, συρίγγιον.
↑ Lophocyrtis = Basket with a crest; λόφος, κυρτίς.
↑ Tricolocampe = Caterpillar with three joints; τρίς, κῶλον, κάμπη.
↑ Theocorys = Divine helmet; θεός, κόρυς.
↑ Axocorys = Helmet with an internal axis; ἄξις, κόρυς.
↑ Lophocorys = Helmet with a top crest; λόφος, κόρυς.
↑ Theocampe = Divine caterpillar; θεός, κάμπη.
↑ Theocapsa = Divine capsule; θεός, κάψα.
↑ Tricolocapsa = Three-jointed capsule; τρικῶλον, κάψα.
↑ Phrenocodon = Bell with diaphragm; φρήν, κώδων.
↑ Stichopilium = Hat with a row of joints; στίχος, πίλιον.
↑ Artopilium = Loaf-hat; ἄρτος, πίλιον.
↑ Pteropilium = Winged hat; πτερόν, πίλιον.
↑ Stichocampe = Caterpillar with a row of joints; στίχος, κάμπη.
↑ Stichopterium = Row-wing; στίχος, πτέριον.
↑ Podocampe = Caterpillar with feet; πούς, κάμπη.
↑ Stichopodium = Row-foot; στίχος, πόδιον.
↑ Stichopera = Row-pouch; στίχος, πήρα.
↑ Cyrtopera = Basket-pouch; κύρτος, πήρα.
↑ Artopera = Bread-pouch; ἄρτος, πήρα.
↑ Stichophormis = Row-basket; στίχος, φορμίς.
↑ Phormocampe = Latticed caterpillar; φόρμος, κάμπη.
↑ Artophormis = Bread-basket; ἄρτος, φορμίς.
↑ Cyrtophormis = Plaited-basket; κύρτος, φορμίς.
↑ Artophæna = Bread-shell; ἄρτος, φαῖνα.
↑ Stichophæna = Row-shell; στίχος, φαῖνα.
↑ Lithostrobus = Cone of silex; λίθος, στρόβος.
↑ Dictyomitra = Net-cap; δίκτυον, μίτρα.
↑ Stichocorys = Row-helmet; στίχος, κόρυς.
↑ Artostrobus = Bread-cone; ἄρτος, στρόβος.
↑ Lithomitra = Stone-cap; λίθος, μίτρα.
↑ Eucyrtidium = Nice small basket; εὖ, κυρτίδιον.
↑ Eusyringium = Nice small tube; εὖ, συρίγγιον.
↑ Siphocampe = Caterpillar with a tube; σίφων, κάμπη.
↑ Lithocampe = Stone-caterpillar; λίθος, κάμπη.
↑ Spirocyrtis = Spiral basket; σπεῖρα, κυρτίς.
↑ Spirocampe = Spiral caterpillar; σπεῖρα, κάμπη.
↑ Cyrtocapsa = Basket-capsule; κύρτος, κάψα.
↑ Stichocapsa = Jointed capsule; στίχος, κάψα.
↑ Artocapsa = Bread-shaped capsule; ἄρτος, κάψα.

[Nt113-1] Tripocalpis = Urn with three feet; τρίπους, καλπίς.

[Nt114-2] Tripodonium = Shell with three feet.

[Nt115-3] Tripterocalpis = Urn with three wings; τρίπτερος, καλπίς.

[Nt116-4] Trissopilium = Small hat with three wings; τρίσσος, πίλιον.

[Nt117-5] Archipilium = Primordial hat; ἀρχιπίλιον.

[Nt118-6] Tripilidium = Small hat with three feet; τρία, πιλίδιον.

[Nt119-7] Tripodiscium = Shell with three small feet; τρία, ποδίσκιον.

[Nt120-8] Tridictyopus = Shell with three lattice-feet; τρία, δίκτυον, πούς.

[Nt121-9] Euscenium = Nice small tent; εὖ, σκηνίον.

[Nt122-10] Cladoscenium = Small tent with branched axis; κλαδός, σκηνίον.

[Nt123-11] Archiscenium = Primordial tent; ἀρχί, σκηνίον.

[Nt124-12] Pteroscenium = Small tent with wings; πτερόν, σκηνίον.

[Nt125-13] Peridium = Small pouch; πηρίδιον.

[Nt126-14] Archipera = Primordial pouch; ἀρχί, πήρα.

[Nt127-15] Archibursa = Primordial bottle; ἀρχί, βύρσα.

[Nt128-16] Bathropyramis = Pyramid with ladders; βάθρον, πυραμίς.

[Nt129-17] Cinclopyramis = Lattice-pyramid; κιγκλίς, πυραμίς.

[Nt130-18] Peripyramis = Pyramid with an envelope; περί, πυραμίς.

[Nt131-19] Litharachnium = Spider-web of silex; λίθος, ἀράχνιον.

[Nt132-20] Cladarachnium = Spider-web with branched threads; κλαδός, ἀράχνιον.

[Nt133-21] Cystophormis = bladder-basket; κυστή, φορμίς.

[Nt134-22] Haliphormis = Sea-basket; ἅλς, φορμίς.

[Nt135-23] Archiphormis = Primordial-basket; ἀρχί, φορμίς.

[Nt136-24] Halicalyptra = Sea-veil; ἅλς, καλύπτρα.

[Nt137-25] Carpocanistrum = Small fruit-basket; καρπός, κανίστρον.

[Nt138-26] Arachnocalpis = Urn enveloped by spider's web; ἀράχνη, καλπίς.

[Nt139-27] Phænocalpis = Urceolate shell; φαῖνα, καλπίς.

[Nt140-28] Phænoscenium = Tent-shaped shell; φαῖνα, σκηνίον.

[Nt141-29] Calpophæna = Urceolate shell; καλπίς, φαῖνα.

[Nt142-30] Archiphæna = Primordial shell; ἀρχί, φαῖνα.

[Nt143-31] Cornutella = Small horn; diminutive of cornu.

[Nt144-32] Cornutanna = Horn-shaped; Cornuta.

[Nt145-33] Archicorys = Principal helm; ἀρχίκορυς.

[Nt146-34] Cyrtocalpis = Basket-urn or wicker-pitcher; κύρτος, καλπίς.

[Nt147-35] Mitrocalpis = Turban basket; μίτρα, καλπίς.

[Nt148-36] Spongocyrtis = Spongy basket; σπόγγος, κυρτίς.

[Nt149-37] Halicapsa = Sea-capsule; ἅλς, κάψα.

[Nt150-38] Archicapsa = Primordial capsule; ἀρχίκαψα.

[Nt151-39] Dictyophimus = Net goblet; δίκτυον, φιμός.

[Nt152-40] Tripocyrtis = Basket with a tripod; τρίπος, κυρτίς.

[Nt153-41] Sethopilium = Small fenestrated hat; σήθω, πίλιον.

[Nt154-42] Lithomelissa = Stone bee; λίθος, μέλισσα.

[Nt155-43] Psilomelissa = Smooth bee; ψιλός, μέλισσα.

[Nt156-44] Spongomelissa = Spongy bee; σπόγγος, μέλισσα.

[Nt157-45] Clathrocanium = Basket of network; κλῆθρα, κάνεον.

[Nt158-46] Lamprodiscus = Splendid disk; λαμπρός, δίσκος.

[Nt159-47] Lampromitra = Splendid turban; λαμπρός, μίτρα.

[Nt160-48] Callimitra = Beautiful turban; κάλλὶς, μίτρα.

[Nt161-49] Clathromitra = Lattice-turban; κλῆθρα, μίτρα.

[Nt162-50] Clathrocorys = Lattice-helmet; κλῆθρα, κόρυς.

[Nt163-51] Eucecryphalus = Nice net-cap, εὖ, κεκρύφαλος.

[Nt164-52] Amphiplecta = Shell at both poles open, with framework around; ἀμφίπληκτα.

[Nt165-53] Lychnocanium = Lantern-basket: λύχνος, κάνεον.

[Nt166-54] Lychnodictyum = Lantern with network; λύχνος, δίκτυον.

[Nt167-55] Sethopera = Sieve-pouch; σήθω, πήρα.

[Nt168-56] Lithopera = Stone-pouch; λίθος, πήρα.

[Nt169-57] Micromelissa = Small bee; μικρός, μέλισσα.

[Nt170-58] Peromelissa = Pouch-bee; πήρα, μέλισσα.

[Nt171-59] Sethomelissa = Sieve-bee; σήθω, μέλισσα.

[Nt172-60] Tetrahedrina = Small tetrahedron; τετράεδρον.

[Nt173-61] Sethochytris = Sieve-pot; σήθω, χυτρίς.

[Nt174-62] Clathrolychnus = Fenestrated lantern; κλῆθρα, λύχνος.

[Nt175-63] Sethophormis = Sieve-basket; σήθω, φορμίς.

[Nt176-64] Sethamphora = Sieve-pitcher; σήθω, ἀμφορεύς.

[Nt177-65] Sethopyramis = Sieve-pyramid; σήθω, πυραμίς.

[Nt178-66] Plectopyramis = Woven pyramid; πλεκτός, πυραμίς.

[Nt179-67] Spongopyramis = Spongy pyramid; σπόγγος, πυραμίς.

[Nt180-68] Acanthocorys = Spiny Helmet; ἄκανθα, κόρυς.

[Nt181-69] Arachnocorys = helmet with a cobweb; ἀράχνη, κόρυς.

[Nt182-70] Anthocyrtoma = Flower-arch; ἄνθος, κύρτωμα.

[Nt183-71] Anthocyrtis = Flower-basket; ἄνθος, κυρτίς.

[Nt184-72] Anthocyrtium = Flower-basket; ἄνθος, κύρτιον.

[Nt185-73] Anthocyrtidium = Small flower-basket; ἄνθος, κυρτίδιον.

[Nt186-74] Carpocanium = Fruit-basket; καρπός, κάνεον.

[Nt187-75] Sethophæna = Sieve-shell; σήθω, φαῖνα.

[Nt188-76] Clistophæna = Closed shell; κλειστός, φαῖνα.

[Nt189-77] Sethoconus = Sieve-cone; σήθω, κῶνος.

[Nt190-78] Periarachnium = Shell enveloped by cobweb; περί, ἀράχνιον.

[Nt191-79] Sethocephalus = Sieve-head; σήθω, κεφαλή.

[Nt192-80] Sethocyrtis = Sieve-basket; σήθω, κυρτίς.

[Nt193-81] Sethocorys = Sieve-helmet; σήθω, κόρυς.

[Nt194-82] Lophophæna = Shell with a top-knot; λόφος, φαίνω.

[Nt195-83] Dictyocephalus = Latticed head; δίκτυον, κεφαλή.

[Nt196-84] Sethocapsa = Sieve-capsule; σήθω, κάψα.

[Nt197-85] Dicolocapsa = Two-jointed capsule; δίκωλος, κάψα.

[Nt198-86] Cryptocapsa = Hidden capsule; κρυπτός, κάψα.

[Nt199-87] Pterocorys = Helmet with wings; πτερόν, κόρυς.

[Nt200-88] Theopilium = Divine hat; θεός, πίλιον.

[Nt201-89] Corocalyptra = Coif or hood of a girl; κόρη, κάλυπτρα.

[Nt202-90] Dictyoceras = Reticulated horn; δίκτυον, κέρα.

[Nt203-91] Pteropilium = Small hat with wings; πτερόν, πίλιον.

[Nt204-92] Theopodium = Divine foot; θεός, πόδιον.

[Nt205-93] Pterocanium = Basket with wings; πτερόν, κάνεον.

[Nt206-94] Pterocodon = Bell with wings; πτερόν, κώδων.

[Nt207-95] Dictyocodon = Net-bell; δίκτυον, κώδων.

[Nt208-96] Pleuropodium = Shell with ribs and feet; πλεῦρα, πόδιον.

[Nt209-97] Podocyrtis = Basket with feet; πούς, κυρτίς.

[Nt210-98] Thyrsocyrtis = Basket with a thyrsus or apical rod; θύρσος, κυρτίς.

[Nt211-99] Dictyopodium = Shell with latticed feet; δίκτυον, πόδιον.

[Nt212-100] Lithornithium = Siliceous bird; λίθος, ὀρνίθιον.

[Nt213-101] Sethornithium = Latticed bird; σήθω, ὀρνίθιον.

[Nt214-102] Theopera = Divine pouch; θεός, πήρα.

[Nt215-103] Rhopalocanium = Basket with clubs; ῥόπαλον, κάνεον.

[Nt216-104] Rhopalatractus = Spindle with clubs; ῥόπαλον, ἄτρακτος.

[Nt217-105] Lithochytris = Pot of silex; λίθος, χυτρίς.

[Nt218-106] Theophormis = Divine basket; θεός, φορμίς.

[Nt219-107] Phormocyrtis = Plaited basket; φορμός, κυρτίς.

[Nt220-108] Alacorys = Wing-helmet.

[Nt221-109] Cycladophora = Bearing a female robe; κυκλάς, φόρος.

[Nt222-110] Calocyclas = Beautiful female robe; καλός, κυκλάς.

[Nt223-111] Clathrocyclas = Fenestrated female robe; κλῆθρα, κυκλάς.

[Nt224-112] Lamprocyclas = Splendid female robe; λαμπρός, κυκλάς.

[Nt225-113] Diplocyclas = Female robe with a double girdle; δίπλόος, κυκλάς.

[Nt226-114] Hexalatractus = Spindle with six wings; ἕξαλα, ἄτρακτος.

[Nt227-115] Theophæna = Divine shell; θεός, φαῖνα.

[Nt228-116] Theocalyptra = Divine veil; θεός, καλύπτρα.

[Nt229-117] Cecryphalium = Net-cap; κεκρυφάλιον.

[Nt230-118] Theoconus = Divine cone; θεός, κῶνος.

[Nt231-119] Lophoconus = Cone with a crest; λόφος, κῶνος.

[Nt232-120] Theocyrtis = Divine basket; θεός, κυρτίς.

[Nt233-121] Theosyringium = Divine tube; θεός, συρίγγιον.

[Nt234-122] Lophocyrtis = Basket with a crest; λόφος, κυρτίς.

[Nt235-123] Tricolocampe = Caterpillar with three joints; τρίς, κῶλον, κάμπη.

[Nt236-124] Theocorys = Divine helmet; θεός, κόρυς.

[Nt237-125] Axocorys = Helmet with an internal axis; ἄξις, κόρυς.

[Nt238-126] Lophocorys = Helmet with a top crest; λόφος, κόρυς.

[Nt239-127] Theocampe = Divine caterpillar; θεός, κάμπη.

[Nt240-128] Theocapsa = Divine capsule; θεός, κάψα.

[Nt241-129] Tricolocapsa = Three-jointed capsule; τρικῶλον, κάψα.

[Nt242-130] Phrenocodon = Bell with diaphragm; φρήν, κώδων.

[Nt243-131] Stichopilium = Hat with a row of joints; στίχος, πίλιον.

[Nt244-132] Artopilium = Loaf-hat; ἄρτος, πίλιον.

[Nt245-133] Pteropilium = Winged hat; πτερόν, πίλιον.

[Nt246-134] Stichocampe = Caterpillar with a row of joints; στίχος, κάμπη.

[Nt247-135] Stichopterium = Row-wing; στίχος, πτέριον.

[Nt248-136] Podocampe = Caterpillar with feet; πούς, κάμπη.

[Nt249-137] Stichopodium = Row-foot; στίχος, πόδιον.

[Nt250-138] Stichopera = Row-pouch; στίχος, πήρα.

[Nt251-139] Cyrtopera = Basket-pouch; κύρτος, πήρα.

[Nt252-140] Artopera = Bread-pouch; ἄρτος, πήρα.

[Nt253-141] Stichophormis = Row-basket; στίχος, φορμίς.

[Nt254-142] Phormocampe = Latticed caterpillar; φόρμος, κάμπη.

[Nt255-143] Artophormis = Bread-basket; ἄρτος, φορμίς.

[Nt256-144] Cyrtophormis = Plaited-basket; κύρτος, φορμίς.

[Nt257-145] Artophæna = Bread-shell; ἄρτος, φαῖνα.

[Nt258-146] Stichophæna = Row-shell; στίχος, φαῖνα.

[Nt259-147] Lithostrobus = Cone of silex; λίθος, στρόβος.

[Nt260-148] Dictyomitra = Net-cap; δίκτυον, μίτρα.

[Nt261-149] Stichocorys = Row-helmet; στίχος, κόρυς.

[Nt262-150] Artostrobus = Bread-cone; ἄρτος, στρόβος.

[Nt263-151] Lithomitra = Stone-cap; λίθος, μίτρα.

[Nt264-152] Eucyrtidium = Nice small basket; εὖ, κυρτίδιον.

[Nt265-153] Eusyringium = Nice small tube; εὖ, συρίγγιον.

[Nt266-154] Siphocampe = Caterpillar with a tube; σίφων, κάμπη.

[Nt267-155] Lithocampe = Stone-caterpillar; λίθος, κάμπη.

[Nt268-156] Spirocyrtis = Spiral basket; σπεῖρα, κυρτίς.

[Nt269-157] Spirocampe = Spiral caterpillar; σπεῖρα, κάμπη.

[Nt270-158] Cyrtocapsa = Basket-capsule; κύρτος, κάψα.

[Nt271-159] Stichocapsa = Jointed capsule; στίχος, κάψα.

[Nt272-160] Artocapsa = Bread-shaped capsule; ἄρτος, κάψα.

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