Report on the Radiolaria/Spyroidea

by Ernst Haeckel

Order VI. CYRTELLARIA, Haeckel, 1881.

Definition.—Nassellaria with a complete lattice-shell enveloping the central capsule.

Suborder I. SPYROIDEA, Haeckel.

Spyridina, Ehrenberg (pro parte), 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.
Zygocyrtida, Haeckel, 1862, Monogr. d. Radiol., p. 291.
Zygocyrtida, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 501.
Acanthodesmida, R. Hertwig, 1879, Organismus der Radiol., p. 68.
Spyrida vel Spyroidea, Haeckel, 1881, Prodromus, p. 440.

Definition.—Nassellaria with a complete lattice-shell, exhibiting constantly a bilocular cephalis with a sagittal constriction.

The suborder Spyroidea, and the two following closely allied suborders, Botryodea and Cyrtoidea, represent together that large group of Radiolaria which I first described in my Monograph (1862, pp. 272, 280) as the family Cyrtida, but afterwards as a separate order (or sublegion) under the name Cyrtellaria (1883, Jena. Sitzungsber., Feb. 16, p. 18). This group comprises all those Monopylea or Nassellaria which possess a complete lattice-shell, whilst the preceding Plectellaria never develop a perfect fenestrated shell enveloping the central capsule. The Spyroidea differ from the other Cyrtellaria (Botryodea and Cyrtoidea) in the bilocular shape of the cephalis, which is bisected by the sagittal ring and a corresponding longitudinal constriction into two symmetrical halves.

The Spyroidea appear in the first system of Polycystina of Ehrenberg (1847, loc. cit., pp. 53, 54) as the fourth of his seven families, under the name Spyridina, with the following definition:—"Testæ nucleo destitutæ (associatæ et coalitæ); cellulæ binæ clathratæ, nucis forma amplæ, strictura longitudinali levius discretæ." Ehrenberg united them with his "Polycystina composita or Spumellaria" and separated them from the closely allied "Polycystina solitaria or Nassellaria." He distinguished among them five genera, two of which have no external appendages (Dictyospyris and Pleurospyris), whilst the other three possess spiny or lamellar appendages (Ceratospyris, Cladospyris, and Petalospyris). These five genera and the accompanying definitions were also repeated in the same terms in the last system of Ehrenberg (1875, loc. cit., p. 157). In my Monograph (1862, pp. 280, 291) the Spyroidea are enumerated as a subfamily of the Cyrtida, under the name Zygocyrtida, with the following definition:—"Lattice-shell divided by an annular sagittal longitudinal constriction into two neighbouring equal joints or chambers." I adopted at that time the above five genera of Ehrenberg, only eight species of which were known.

Richard Hertwig gave in 1879 the first accurate description of the central capsule of the Spyroidea, and demonstrated that they possess the same characteristic structure of the capsule, with a porochora and a podoconus, that is common to all Monopylea. He separated the Zygocyrtida from the other Cyrtida, and united them with the Stephoidea (Lithocircus) in the family Acanthodesmida. In my Prodromus (1881, p. 449) I adopted that division and put the "Spyrida or Spyroidea" as a separate family between the Cyrtoidea and Stephoidea. I there gave the following definition:—Monopylaria gemina, testa silicea clathrata gemina, cameris binis juxta compositis, annulo verticali sagittali contiguis, capsula centrali a testa inclusa. Promorpha dipleura vel bilaterali, dextro et sinistro antimero symmetricis, plano sagittali annuloque separatis. Polum superiorem axis verticalis vel principalis plerumque spina apicalis (vel occipitalis) occupat, polum inferiorem ostium clathratum (poris tribus aut quatuor aut pluribus) et spina caudalis (posterior). Ad dextram et sinistram duæ spinæ laterales distant. Ab hac forma tripoda (Monocyrtida triradiata acuta cum annulo mediano) diversæ Spyridum formæ derivandæ sunt." I there divided the Spyrida into seven subfamilies and forty-eight genera. Bütschli in 1882 published accurate researches on the Zygocyrtida in his Beiträge zur Kenntniss der Radiolarien-Skelete, insbesondere der der Cyrtida (Zeitschr. f. wiss. Zool., vol. xxxvi. p. 501, Taf. xxxii.). He gave a very exact anatomical description of the skeleton of several fossil Spyroidea of Barbados, and pointed out their close affinity to the Acanthodesmida on the one hand, and to the Cyrtida on the other. Regarding their phylogenetical relation, he supposed that the Zygocyrtida have descended from the Acanthodesmida (our Stephoidea) and are the ancestors of all other Cyrtida. The best part of this valuable paper of Bütschli is his exact description of the sagittal ring and its apophyses, producing the basal plate; and the general conception thus derived of the essential parts of the skeleton in all Monopylea, bearing a sagittal ring. But his general conclusions were partly erroneous, since the fossil Spyroidea and Cyrtoidea of Barbados, upon which they were founded, contain only the minority of genera of the large group; and many important and typical forms remained unknown to him.

The numerous new genera discovered in the rich collection of the Challenger, and mainly in the wonderful Radiolarian ooze of the Central Pacific (Stations 263 to 274) throw a new light upon the complicated affinities of the whole group, and manifest a far greater richness in developmental variations and admirable morphological productions than Bütschli could suppose. The following description, however, must remain very incomplete, since the exact and thorough study of all individual forms, in the same manner as Bütschli had done in the case of a small number of species, would require several years. I can therefore only give the basis of further researches.

In the majority of Spyroidea the three essential elements of the Nassellarian skeleton are easily recognisable, viz.:—A, the vertical sagittal ring of the Stephoidea; B, the basal tripod of the Plectoidea, and C, the latticed cephalis of the Cyrtellaria. These three elements are constantly so combined that the primary sagittal ring bisects the cavity of the lattice-shell and produces an external, longitudinal, more or less distinct constriction, separating the lateral inflated halves of the bilocular cephalis; while the three divergent feet of the basal tripod descend from the cortinar or basal plate of the cephalis. The number of the feet is often augmented; they are rarely wanting (probably reduced). The sagittal ring is constantly present, though its relation to the shell-wall exhibits many modifications. The bilocular form of the fenestrated cephalis, with its sagittal constriction, is characteristic of all true Spyroidea, and separates them from the Botryodea (with multilobate cephalis) on the one hand, and from the Cyrtoidea (with simple cephalis) on the other. There are, however, some intermediate forms between these three suborders of Cyrtellaria, which show a direct transition to one another. Almost constantly the length of the three dimensive axes in the cephalis of the Spyroidea is so different that the lateral or frontal axis is the longest, the sagittal or dorso-ventral axis the shortest, and the principal or longitudinal axis intermediate between them. As in all dipleuric or bilaterally symmetrical forms, the two poles of the frontal axis are equal, whilst the two poles of the sagittal and of the principal axis are more or less different. In only a few forms of Spyroidea these differences are difficult to make out; usually the dorsal side is distinctly different from the ventral, and the apical side from the basal. A perfect knowledge of the dipleuric shell requires therefore accurate observation from all six sides.

The suborder of Spyroidea is here divided into four different families. In the first and original family, the Zygospyrida, the shell is represented by the bilocular cephalis only. The second family, Tholospyrida, is distinguished by a fenestrated cupola or galea, a hemispherical or conical dome, arising from the upper or coryphal face of the cephalis. In the third family, Phormospyrida, a thorax is developed, or a fenestrated basal chamber, arising from the lower or basal face of the cephalis. The fourth family, Androspyrida, combines the characters of the second and the third family, a galea arising from the upper and a thorax from the lower face of the cephalis.

The bilocular cephalis, as the most important and constant part of the skeleton in all Spyroidea, requires a further general consideration. Its lattice-work, very variable in the numerous species, is usually more or less different on the six sides of the nut-shaped shell. Its most important part is the horizontal basal plate or lower face, and the sagittal ring arising from it in the vertical median plane. This part of the shell corresponds exactly to the skeleton of the Semantida, and exhibits the same modifications as in that family; it is therefore probable that the majority of the Spyroidea (if not the whole group) have been derived directly from the Semantida by further development of network from the fenestrated ring of Clathrocircus. Whilst in this latter Semantid the two lateral sides of the central capsule remain naked, in the Spyroidea they become enclosed and covered by lattice-work, which arises on the right and left from the ring. In some forms, however, as in the Ceratospyris acuminata of Hertwig, and in my Perispyrida, the frontal ring also of the Coronida and the mitral ring of the Tympanida appear as the initial parts of a complete latticed cephalis.

The basal plate of the cephalis, or the "cortinar plate," the "Basal-Scheibe" of Bütschli, has constantly, according to this author, two pairs of pores, an anterior smaller pair of jugular pores (the pores I of Bütschli) and a posterior larger pair of cardinal pores (the pores II in his description) (compare Pl. 95, figs. 3, 6). This applies to the majority of Spyroidea, but by no means to the whole group. We find basal plates with two pores only (Pl. 95, fig. 1), with three pores (figs. 2, 5), with six pores (figs. 4, 7), with nine pores (Pl. 87, fig. 2), &c. The forms with two basal pores may be derived directly from Semantis (Pl. 92, figs. 1, 2); the common forms with four pores from Semantrum (figs. 3-5); the rarer forms with six pores from Semantidium (figs. 6, 7); and the forms with three pores from Cortiniscus, &c. In this as well as in other respects the variety of different forms and of developmental variations is far greater than Bütschli (1882, loc. cit.) supposed. The bars between the pores of the basal plate possess the same value and the same names as in the Semantida (compare above, p. 954).

The coryphal plate of the cephalis, its upper or apical lattice-plate, does not exhibit such important differences as the opposite basal plate, is far less variable, and is usually pierced by numerous, smaller pores. Some larger pores lie, often in pairs, on the right and left side of the sagittal constriction, and have in some groups a regular form and disposition. Either in the middle of the coryphal plate, or (usually) nearer to its dorsal margin, there arises in majority of Spyroidea an apical horn, directed either vertically or more or less obliquely backwards. In many Spyroidea three horns are developed in the coryphal plate, the odd middle apical horn and two paired frontal or lateral horns arising on each side of the latter and directed more forwards (Pl. 84, figs. 9-12). Sometimes the apical horn disappears, while the two frontal horns remain (Pl. 95, fig. 12).

The anterior or ventral plate of the cephalis (the "Hinterseite" of Bütschli), and the posterior or dorsal side (the "Vorderseite" of that author), exhibit in the majority of Spyroidea more or less marked differences in the number, form, and disposition of their pores, which require a far more accurate description than is here possible. Usually the sagittal constriction of these two plates, produced by the primary vertical ring, is deeper and sharper in the middle of the ventral than in that of the dorsal plate. On both sides of the ring there appear in each plate usually two or three pairs of larger pores, whilst numerous smaller pores are situated towards the lateral sides. We may distinguish the large pores of the ventral plate as facial pores (upper orbital, middle nasal, and lower maxillary pores), and the opposite large pores of the dorsal plate as occipital pores (upper epoccipital, middle mesoccipital, and lower suboccipital pores). A closer comparison of these pores, and of the separating bars in the numerous Spyroidea, may show a regularity of development similar to that offered by the homologies of the parts in the skeleton of the Echinodermata, or of the bones in the skull of the Vertebrata.

The two convex lateral plates of the cephalis, or the right and left sides, both symmetrically equal, do not exhibit the same regularity in the shape, number, and disposition of the pores that the four other sides do. Usually their pores are much smaller and more numerous. In very few forms only a distinct frontal ring is visible (corresponding to that of the Coronida), and in this case the lateral pores are sometimes disposed symmetrically on both sides of this ring. These Spyroidea may have arisen directly from corresponding forms of Coronida.

The sagittal ring (or the primary vertical ring) inherited from the Stephanida and Semantida, shows in the Spyroidea great variety in its form and in its relation to the cephalis. These variations are far greater than Bütschli (1882, loc. cit.) supposed. We may distinguish the following six principal cases:—A. The ring lies completely in the wall of the cephalis, and causes a deep sagittal constriction in it. In this case the lower part or basal segment of the ring separates the basal pores into pairs; its anterior part or ventral rod the facial pores; its upper part or coryphal rod the apical pores; and its posterior part or dorsal rod the occipital pores. No part of the ring is free in the shell-cavity. B. The greater part of the ring lies enclosed in the shell-wall; only its dorsal rod arises free in the shell-cavity and ascends vertically or obliquely to the apex, where it is usually prolonged into the apical horn. This seems to be the most common case. C. The coryphal and the basal part of the ring lie enclosed in the shell-wall, with its dorsal and ventral rod free in the shell-cavity; the dorsal rod ascends vertically to the apex, the ventral rod obliquely upwards to the upper part of the facial plate (the nasal or orbital region). This case, regarded by Bütschli as the usual one, is far less common than he supposed. D. The greater part of the ring lies free in the shell-cavity, its basal rod only is enclosed in the shell-wall, and separates the right from the left group of the cortinar pores. This case seems to be rarer than the preceding. E. The whole ring lies free in the shell-cavity, and is connected with the sagittal constriction of the shell-wall by numerous short radial beams. The distance of the shell-wall from the enclosed ring is usually least on the basal rod, and greatest on the dorsal rod. F. The whole ring lies free in the shell-cavity (as in the preceding case), and is connected by numerous short radial beams with a secondary larger, concentric sagittal ring, which is developed in the longitudinal constriction of the shell-wall.

Comparing these six principal cases, in respect of the relation of the primary sagittal ring to the cephalis of the Spyroidea, we may suppose that they represent together a continuous phylogenetical series of which the first (A) is the original, and the last (F) the latest case; and that the true cause of the various changes is a successive separation of the ring, which becomes more and more free and independent from the lattice-plate of the cephalis. Since the intimate study of the structure of the cephalis in many Spyroidea is very difficult, it requires further accurate observations (from all six sides of the shell). There are also some other more difficult complications of its structure, which cannot be solved without exact study and extended comparison.

Of peculiar importance for the differentiation of the numerous genera of the Spyroidea are the basal feet or the descending and diverging apophyses, which are developed from the base of their cephalis. In general they exhibit the same typical shape which we find in the Plectellaria as well as in the Cyrtoidea, and which we regard therefore as an important common character of the majority of Nassellaria. We may therefore distinguish here also the three primary, and the other ones as secondary feet. The three primary feet, or the "cortinar feet," are the same that we found in the Plagonida and Plectanida, in Cortina and Cortiniscus among the Stephoidea, and in the majority of Cyrtoidea. They also reappear in the same characteristic disposition and connection with the basal plate of the cephalis, in the majority of Spyroidea. The odd caudal foot (c) is the lower prolongation of the dorsal rod of the sagittal ring, which is prolonged upwards into the apical horn. The two paired pectoral feet, however (p′, p′′), are the descending prolongations of the coracal rods (e) which separate the jugular pores (i) from the cardinal pores (k) of the cortinar plate (compare Pl. 95, figs. 2-6).

The three cortinar feet are nearly equally developed in the majority of Spyroidea (compare Pls. 84, 89). But often the odd caudal foot exhibits a different shape from that of the two paired pectoral feet, and in many genera of the group it becomes more or less rudimentary. It has quite disappeared in the subfamily Dipospyrida (Pl. 85); here the two pectoral feet only are developed (often excessively), and are usually opposite in the frontal plane. Such dipodal forms, very common in the Spyroidea, are never found in the Cyrtoidea.

The secondary feet, which we contrast with the three primary feet as later productions, exhibit great variations in number and development. Very frequently three interradial secondary feet become developed, alternating with the three primary cortinar or perradial feet, and opposed to them in pairs (Pl. 95, figs. 7, 8). In these hexapodal Spyroidea (or Hexaspyrida) an odd anterior or sternal foot (z) is opposite to the odd caudal foot, and two paired posterior or tergal feet (t′, t′′) to the two pectoral feet. When the sternal foot becomes rudimentary or lost, pentapodal forms arise (Pentaspyrida, Pl. 95, figs. 9-11), and when the two odd feet (caudal and sternal) disappear, tetrapodal forms arise with two pairs of feet (Therospyrida, Pl. 89, figs. 5, 6). The latter differ from those quadrupedal forms in which two opposite sagittal feet (the caudal and sternal) alternate in the form of a cross with two paired lateral or pectoral feet (Tetraspyrida, Pl. 53, figs. 19, 20). In many Spyroidea the number of basal feet is greatly increased, and they form a regular radial corona around the basal plate, like a circle of tentacles (Polyspyrida, Pl. 87). In this latter case the feet are usually flat and lamellar, whilst in the other groups they exhibit a very variable form, as is seen in Pls. 83-89.

The Central Capsule of the Spyroidea has been accurately observed in only a few genera, and requires a further exact examination regarding the different modifications which occur in their different families. It is very probable that these will agree with the well known modifications in the corresponding groups of Cyrtoidea. The characteristic Monopylean structure of the capsule (with porochora and podoconus) was first described by Richard Hertwig in his Ceratospyris acuminata (loc. cit., p. 72, taf. vii. fig. 2). I found the same afterwards in many other forms. In the Zygospyrida and Tholospyrida the central capsule seems to be usually bilobate (bisected by the sagittal ring), and enclosed in the two chambers of the cephalis. The two lobes of the capsule (right and left) are equal and connected by a smaller middle part, which contains the transverse elliptical nucleus and is enclosed by the sagittal ring; often each lobe contains a large oil-globule. In some forms, however, three or four lobes (sometimes perhaps more) are developed, which pierce the cortinar pores of the basal plate and depend freely between the basal feet (Pl. 53, fig. 19). In the Phormospyrida and Androspyrida the formation of such basal lobes seems to be more frequent; they are here enclosed by the thorax. Usually each lobe contains a large oil-globule. In Nephrospyris (Pl. 90) and in some similar genera the central capsule is violin-shaped, deeply bisected by the sagittal ring; in each of the two lobes a series of oil-vesicles is developed at both poles of the transverse axis (figs. 7, 10); the nucleus, a transverse cylindrical body, is placed in the latter. In the periphery of the voluminous calymma of this singular genus a large number of globular cells are developed (figs. 7, 10), probably symbiotic xanthellæ. In some forms of Nephrospyris these xanthellæ are enclosed by a peculiar inflated girdle, developed in the periphery of the kidney-shaped skeleton (Pl. 90, figs. 1, 4-6).

Synopsis of the Families of Spyroidea.

Shell without thorax; no second shell-joint, developed from the base of the cephalis.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Cephalis without galea (or apical cupola),	1. Zygospyrida.
		Cephalis with a galea (or apical cupola),	2. Tholospyrida.
Shell with a thorax, or a second shell-joint, developed from the base of the cephalis.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Cephalis without galea (or apical cupola),	3. Phormospyrida.
		Cephalis with a galea (or apical cupola),	4. Androspyrida.

Family LII. Zygospyrida, n. fam. (Pls. 84-87).

Definition.—Spyroidea without galea and thorax; the shell consisting of the bilocular cephalis only and its apophyses.

The family Zygospyrida is by far the richest among the four families of Spyroidea, the number of genera in the whole suborder amounting to forty-five, in the former to twenty-eight; and the number of species in the latter to two hundred and thirty-seven, in the former to one hundred and seventy-two. The number of individuals also found in many species of Zygospyrida is far greater than in any species of the three other families. The shell of the Zygospyrida is represented by the bilocular cephalis only, and never develops a galea (as in the Tholospyrida) nor a thorax (as in the Phormospyrida and Androspyrida). The three latter families have therefore been derived from the former as their common ancestral group.

The Zygospyrida are very similar and nearly related to the Monocyrtida, and in both groups the cephalis alone represents the whole shell. Therefore in 1882, Bütschli, in the paper mentioned above (p. 1016), maintained the opinion, that these two groups were identical. But there is this important difference between them, that in the Zygospyrida (as in all Spyroidea) the cephalis is bilocular, with a sagittal constriction, separating the right and left chambers. In the Monocyrtida, however (as in all Cyrtoidea), the cephalis is unilocular, forming a quite simple chamber without sagittal constriction. Correspondingly the primary sagittal ring in all Zygospyrida is well preserved and usually complete, while in the Monocyrtida it is never complete, and often quite absent. Another difference is indicated by the form of the central capsule, which in the Zygospyrida is usually bilobed, and more developed in the frontal axis, whilst in the Monocyrtida it is commonly ovate, and more developed in the principal axis.

The important questions of the origin and phylogenetical relation of these two similar groups of Nassellaria form a very complicated and difficult problem, and we do not at present possess the means of solving it. It may be that a part of the Monocyrtida has been derived from the Zygospyrida (as Bütschli erroneously supposes for all), but the contrary is also possible. A third possibility is the independent origin of both groups from the Semantida. But we shall see afterwards, in the description of the Monocyrtida, that a great part of this group may with greater probability be derived from the Plectoidea than from the Stephoidea, and that another part of them has probably been derived quite independently from the Nassellida. Regarding the complicated relations of these similar groups, mentioned above (pp. 892-894), it seems hopeless here to discuss further their difficult affinities; but in any case it seems useful or even necessary to separate the Monocyrtida from the Zygospyrida.

The cephalis of the Zygospyrida possesses all the characteristic features which we have described above as belonging to the Spyroidea in general (p. 1017), and a survey of the Pls. 84-87 exhibits the most important modifications of its shape (compare also Pl. 95, figs. 1-13). Therefore we may avoid useless repetitions by referring to the description given above. We will only point out that the bilocular character of the cephalis (in opposition to the simple cephalis of the Monocyrtida) in the majority of Zygospyrida is apparent on the first view, and that it is always demonstrated by an accurate examination of the sagittal ring and its relation to the longitudinal constriction of the cephalis (compare p. 1019). The basal plate or cortinar plate exhibits usually four typical pores (two smaller jugular, i, and two larger cardinal, k), but this is by no means a general rule, as Bütschli thought; moreover, instead of four cortinar pores, there are frequently found three or six or some other numbers (compare above, p. 1018).

The top of the cephalis in the majority of Zygospyrida bears an apical horn, as an upper prolongation of the dorsal rod of the sagittal ring; it is often of unusual size and shape (Pl. 85, figs. 5-11; Pl. 95, fig. 8, &c.). In several genera two lateral or frontal horns are developed on both sides of the former (Pl. 84, figs. 9-12; Pl. 86, figs. 5-13). Sometimes these two alone are present, while the original apical horn is lost by reduction (Pl. 95, fig. 12). In other genera the apical face bears no horns; probably they are lost by reduction.

The greatest variety of forms is produced in the Zygospyrida by the different number, disposition, and shape of the feet, or the basal apophyses arising from the base of the cephalis. Regarding these remarkable differences, we may distinguish eight subfamilies. The common ancestral group of all are probably the Tripospyrida, which possess the three typical basal feet of Cortina and Cortiniscus, an odd caudal and two paired pectoral feet (Pl. 84). From these may be derived the Dipospyrida (Pl. 85) by loss of the caudal foot, the Tetraspyrida by development of an odd sternal foot (Pl. 53, figs. 7, 8, 19), and the Hexaspyrida by development of three secondary interradial between the three primary perradial feet. The Pentaspyrida may have been derived from the latter by loss of the sternal foot (Pl. 95, figs. 9-11), and the Therospyrida by loss of the two sagittal feet (Pl. 89, figs. 5, 6). The Polyspyrida bear numerous (seven to twelve or more, often twenty to thirty) basal feet, forming a corona around the cortinar plate (Pl. 87); they may have been derived from the Tripospyrida or Hexaspyrida by further multiplication of the feet. Finally, the Circospyrida exhibit no feet at all (Pl. 89, figs. 7-12); they may be derived either from one of the preceding groups by complete reduction and loss of the basal apophyses, or directly from those Semantida which have no feet (Semantis, Semantrum, Clathrocircus, &c.).

Synopsis of the Genera of Zygospyrida.

I. Subfamily Tripospyrida. Three basal feet. (One odd caudal and two paired pectoral.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Apex of the shell with one horn,					441. Tripospyris.
		Apex of the shell with three horns,					442. Triceraspyris.
		Apex of the shell without horns,					443. Tristylospyris.
		Apex with two large coryphal holes, right and left,					444. Cephalospyris.
II. Subfamily Dipospyrida. Two basal lateral feet. (Originally the two pectoral feet.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Two feet free, not grown together.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \\\ \ \end{matrix}}\right.}$	Feet simple, not branched, without lateral spines.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	One horn,	445. Dipospyris.
						No horn,	446. Brachiospyris.
				Feet branched like a tree.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	One horn,	447. Dendrospyris.
				Feet with a series of lateral spines.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	One horn,	448. Dorcadospyris.
		Two feet grown together and uniting to form a ring. Apex with a horn.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Feet simple,			449. Gamospyris.
				Feet with a series of lateral spines,			450. Stephanospyris.
III. Subfamily Tetraspyrida. Two sagittal and two lateral feet.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	Feet simple, not branched.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Apex with one horn,			451. Tetraspyris.
				Apex without a horn,			452. Tessarospyris.
IV. Subfamily Hexaspyrida. Six basal feet.	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Two sagittal, two pectoral, and two tergal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Apex with one horn,			453. Hexaspyris.
				Apex with three horns,			454. Liriospyris.
				Apex without a horn,			455. Cantharospyris.
V. Subfamily Pentaspyrida. Five basal feet.	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	One caudal, two pectoral, and two tergal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Apex with one horn,			456. Clathrospyris.
				Apex with three horns,			457. Ægospyris.
				Apex without a horn,			458. Pentaspyris.
VI. Subfamily Therospyrida. Four paired lateral feet. (Two pectoral and two tergal.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Apex with one horn,					459. Zygospyris.
		Apex with three horns (one apical and two frontal),					460. Elaphospyris.
		Apex with two lateral or frontal horns,					461. Taurospyris.
		Apex without a horn,					462. Therospyris.
VII. Subfamily Polyspyrida. Numerous (seven to twelve or more) basal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right.}$	Apex with one horn,					463. Petalospyris.
		Apex with three horns (one apical and two frontal),					464. Anthospyris.
		Apex with numerous horns,					465. Ceratospyris.
		Apex without a horn,					466. Gorgospyris.
VIII. Subfamily Circospyrida. No basal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Apex with one horn,					467. Circospyris.
		Apex without a horn,					468. Dictyospyris.

Subfamily 1. Tripospyrida, Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida tripoda, with three descending basal feet (the same as in Cortina, an odd posterior or caudal foot and two paired anterior or pectoral feet).

Genus 441. Tripospyris,^[1] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with three basal feet and one apical horn.

The genus Tripospyris (Pl. 84, figs. 1-7) is in the large group of Spyroidea probably the most original and typical form, from which, as a common ancestral form, all other genera of this polymorphous suborder may be derived. The shell is usually shaped like a nut or thorax, and exhibits two paired lateral chambers, which are separated by a distinct sagittal ring and a slighter or deeper sagittal constriction. The dorsal rod of the ring is prolonged at the upper pole into an ascending apical horn, at the lower pole into a descending caudal foot, whilst two paired pectoral or lateral feet arise from the anterior pole of the basal rod. These three divergent basal feet and the apical horn are the same four typical radial spines which we have encountered already in Plagoniscus (Plagonida), in Plectaniscus (Plectanida), in Cortina (Stephanida), and in Cortiniscus (Semantida). Compare above, p. 891. From all these Plectellaria, Tripospyris differs in the development of a complete bilocular lattice-shell, having the characters of the true Spyroidea. The numerous species of this genus may be placed in different subgenera, according to the different number of collar pores or cortinar pores in the basal plate (two, three, four, six, or more). These differences are very important, however difficult to make out; the following system therefore is a provisional one, and requires further accurate observations.

Subgenus 1. Tripospyrantha, Haeckel.

Definition.—Basal plate with two large pores only (the primary jugular pores of Semantis).

1. Tripospyris cortina, n. sp. (Pl. 95, fig. 1).

Shell ovate, smooth, about as long as broad, with slight ovate sagittal stricture, and broad primary ring in its wall. Basal plate with two large kidney-shaped collar pores only (cardinal pores). Facial and occipital plates each with two pairs of large annular pores, and ten to twelve pairs of small lateral pores. Apical horn and the three basal feet of equal length, one and a half times as long as the shell, three-sided prismatic, straight, divergent.

Dimensions.—Shell 0.08 long, 0.09 broad; horn and feet 0.15 long.

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

2. Tripospyris cortiniscus, n. sp. (Pl. 84, fig. 6).

Shell ovate, smooth, one and a third times as long as broad, with sharp ovate sagittal stricture and broad primary ring. Basal plate with two large cardinal pores only. Occipital plate with two pairs of very large pores; facial plate and lateral sides with numerous smaller irregular roundish pores. Apical horn small, conical, curved, half as long as the three basal feet, which are club-shaped and three-edged, with thinner bases and half as long as the shell, strongly divergent.

Dimensions.—Shell 0.12 long, 0.09 broad; horn 0.03 long, feet 0.06 long.

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

3. Tripospyris semantis, n. sp. (Pl. 84, figs. 2, 3).

Shell subspherical, smooth, somewhat broader than long, with slight sagittal stricture and subcircular parietal primary ring. Basal plate with two large semicircular cardinal pores. Facial and occipital plate each with two pairs of large annular pores and an odd large subapical pore; lateral sides with very numerous small roundish pores. Apical horn and caudal foot club-shaped, half as long as the shell, angular, simple; the two pectoral feet somewhat longer, nearly vertical, and at the distal end with a small incision, nearly forked.

Dimensions.—Shell 0.1 long, 0.12 broad; horn and feet 0.05 to 0.07 long.

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

4. Tripospyris diomma, n. sp. (Pl. 84, fig. 5).

Shell thorax-shaped, smooth, twice as broad as long, with deep sagittal stricture, two vaulted ovate bosoms and smaller ovate internal primary ring. Basal plate with two large ovate cardinal pores. Facial plate with three pairs, occipital plate with four pairs of large annular pores; the other lattice-work loose, with small and numerous irregular polygonal pores. Apical horn and caudal feet slender and thin, curved, shorter than half the shell; two pectoral feet also small, widely divergent, more or less curved, deeply forked.

Dimensions.—Shell 0.1 long, 0.16 broad; horn and feet 0.2 to 0.25 long.

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

Subgenus 2. Tripospyrella, Haeckel.

Definition.—Basal plate with three large collar pores (two paired posterior cardinal pores, and an odd anterior sternal pore).

5. Tripospyris triomma, Haeckel.

Ceratospyris triomma, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xxi. fig. 3.

Shell subspherical, tuberculate, with slight sagittal stricture and circular internal ring. Basal plate with three large pores, which are sometimes (but not in every specimen) surrounded by a circle of very small pores. The other lattice-work with numerous small roundish pores. Apical horn small, oblique, about as long as the shell. Three feet very large, cylindrical, curved, widely divergent, four to five times as long as the shell. (In Ehrenberg's description the caudal foot is erroneously described as "frontal spine"; its figure exhibits the basal plate.)

Dimensions.—Shell 0.07 to 0.09 diameter; horn 0.06 long, feet 0.3 to 0.4 long.

Habitat.—Fossil in Tertiary rocks of Barbados.

6. Tripospyris conifera, n. sp. (Pl. 84, figs. 7, 7a).

Shell nearly hemispherical, papillate, with slight sagittal stricture and semicircular internal ring. Basal plate with three large pores (sometimes, as in the figured specimen, with some small accessory peripheral pores). The other lattice-work with subregular circular pores. Apical horn shorter than the three basal feet, but of similar form, like an elegant ovate dimpled cone, spinulate, with a smooth spindle-shaped pedicle, about as long as the shell.

Dimensions.—Shell 0.08 long, 0.1 broad; horn 0.06 long, feet 0.08 long.

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

7. Tripospyris triplecta, n. sp. (Pl. 95, fig. 2).

Shell thorax-shaped, spiny, with deep sagittal stricture and semicircular internal ring. Basal plate with three large collar pores. Facial plate with four pairs, occipital plate with three pairs of large annular pores; the other pores small, subregular, circular. Apical horn and the feet slender, three-sided pyramidal, about as long as the shell.

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

Habitat.—Mediterranean, Corfu (Haeckel), surface.

Subgenus 3. Tripospyrissa, Haeckel.

Definition.—Basal plate with two pairs of collar pores (two larger posterior cardinal pores and two smaller anterior jugular pores).

8. Tripospyris semantrum, n. sp. (Pl. 95, fig. 3).

Shell thorax-shaped, thorny, with deep sagittal stricture and subcircular ring. Basal plate with four large collar pores (two smaller ovate jugular, and two larger pentagonal cardinal pores). Facial and occipital plates also each with two pairs of large annular pores; lateral sides with smaller irregular polygonal pores. Apical horn and the three feet slender, prismatic, divergent, longer than the shell.

Dimensions.—Shell 0.07 long, 0.08 broad; horn and feet 0.11 to 0.13 long.

Habitat.—South Atlantic, Cape of Good Hope (Wilhelm Bleek), surface.

9. Tripospyris capitata, n. sp. (Pl. 84, fig. 1).

Shell subspherical, spiny, with slight sagittal stricture and ovate internal ring. Basal plate with four large collar pores. Facial plate with three pairs and occipital plate with two pairs of large roundish annular pores; lateral lattice with smaller irregular pores. Apical horn and the three feet subcylindrical, about half as long as the shell, straight, divergent, with a spherical, spinulate knob at the distal end.

Dimensions.—Shell 0.09 long, 0.1 broad; horn and feet 0.05 to 0.06 long.

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

10. Tripospyris clavata, Haeckel.

Ceratospyris clavata, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxii. fig. 13, a-c.

Shell subspherical, compressed, rough, with slight sagittal stricture and ovate internal primary ring. Basal plate with four large collar pores (fig. 13a, loc. cit.). The other lattice-work with irregular small roundish pores. Apical horn and the three feet short and thick, scarcely half as long as the shell, with a roundish spinulate knob at the distal end.

Dimensions.—Length of the shell 0.07 long, 0.08 broad; horn and feet 0.02 to 0.03 long.

Habitat.—Fossil in Barbados.

11. Tripospyris tessaromma, n. sp.

Shell nearly cubical, spiny, with deep sagittal stricture and subcircular ring. Basal plate with four large collar pores. Facial and occipital plates each also with two pairs of large square annular pores; lateral pores irregular polygonal. Apical horn half as long as the feet, which are three times the length of the shell, cylindrical, slightly curved.

Dimensions.—Shell 0.1 long, 0.12 broad; horn 0.15 long, feet 0.3 long.

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

Subgenus 4. Tripospyromma, Haeckel.

Definition.—Basal plate with six or more collar pores. Commonly two small anterior jugular pores, two large middle cardinal pores, and two small posterior cervical pores; sometimes several small accessory collar pores.

12. Tripospyris hexomma, n. sp. (Pl. 95, fig. 4).

Shell thorax-shaped, tuberculate, with deep sagittal stricture and semicircular internal primary ring. Basal plate with three pairs of pores. Facial plate with two pairs, occipital plate with four pairs of large annular pores. Lateral pores smaller, irregular, polygonal. Apical horn and caudal foot half as long as the shell and as the two pectoral feet; all four spines cylindrical, two to three times as long as the shell, slightly curved.

Dimensions.—Shell 0.1 long, 0.12 broad; horn and feet 0.2 to 0.4 long.

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

13. Tripospyris semantidium, n. sp.

Shell nut-shaped, thorny, with sharp sagittal stricture and subcircular ring. Basal plate with three pairs of large pores. Facial and occipital plates each with three pairs of large squarish pores. Lateral pores small and numerous, irregular roundish. Apical horn half as long as the shell and the three feet; all four spines straight, cylindrical, with thickened club-shaped end.

Dimensions.—Shell 0.12 long, 0.13 broad; horn 0.06 long, feet 0.15.

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

14. Tripospyris eucolpos, n. sp. (Pl. 84, fig. 4).

Shell thorax-shaped, smooth, with two vaulted bosoms, separated by a deep sagittal stricture and an internal primary ring. Basal plate constricted, with three pairs of collar pores. The other lattice-work with subregular circular pores. Apical horn and the three feet shorter than the shell, straight, divergent; their inner half thinner, cylindrical, smooth, their outer half an ovate dimpled cone.

Dimensions.—Shell 0.1 long, 0.13 broad; horn and feet 0.06 long.

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

15. Tripospyris tribrachiata, Haeckel.

Cladospyris tribrachiata, Ehrenberg, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xxi. fig. 8.

Shell subspherical, smooth, with slight sagittal stricture and numerous, very small circular pores. Basal plate with numerous small pores. Apical horn and the three divergent feet very large and stout, straight, three-sided prismatic, with dentate edges, two to three times as long as the shell.

Dimensions.—Shell diameter 0.05; horn and feet 0.1 to 0.15 long.

Habitat.—Fossil in Barbados.

16. Tripospyris furcata, n. sp. (Pl. 83, fig. 11).

Shell nut-shaped, smooth, with deep sagittal stricture and broad ring. Basal plate with three pairs of small pores. Facial and occipital plates each with a pair of very large holes. Apical horn and caudal foot simple conical, two pectoral feet forked or irregularly branched.

Dimensions.—Shell 0.08 long, 0.12 broad; horn and feet 0.05 long.

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

Genus 442. Triceraspyris,^[2] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with three basal feet and three coryphal horns.

The genus Triceraspyris has arisen from the preceding ancestral Tripospyris by the development of two paired frontal horns, so that the shell here bears six appendages, three superior or coryphal spines and three inferior or basal spines; two of these are odd and dorsal (the apical horn and the caudal foot), the four others are paired and ventral (the frontal horns and the pectoral feet). The numerous species of this genus may be divided into three subgenera, according to the simple or branched shape of the ascending horns and of the descending feet.

Subgenus 1. Triospyris, Haeckel, 1881, Prodromus, p. 441.

Definition.—Horns and feet simple, not branched nor forked.

1. Triceraspyris tripodiscus, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores irregular roundish, two pairs of larger pores on each side of the ring. Basal plate with three large pores. Horns and feet slender cylindrical, straight, divergent; three horns about as long as the shell, three feet twice as long.

Dimensions.—Shell 0.06 long, 0.08 broad; horn 0.05 long, feet 0.1.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

2. Triceraspyris cortiniscus, n. sp.

Shell subspherical, smooth, with slight sagittal stricture. Pores small and numerous, subregular roundish. Basal plate with two large pores (?). Apical horn conical, short, half as long as the shell and the two lateral horns, which are curved outwards. All three feet equal, cylindrical, strongly curved and divergent, twice to three times as long as the shell.

Dimensions.—Shell 0.07 long, 0.08 broad; horn 0.04 to 0.08 long, feet 0.15 to 0.2 long.

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

3. Triceraspyris didiceros, Haeckel.

Ceratospyris didiceros, Ehrenberg, 1875, Abhandl. d. Akad. d. Wiss. Berlin, p. 66, Taf. xxi. fig. 6.

Shell nut-shaped, thorny, with superficial sagittal stricture. Pores large, irregular roundish. Basal plate with four larger pores. Apical horn and caudal foot small, conical, shorter than half the shell. The two frontal horns longer, slender conical. The two pectoral feet very large, cylindrical, nearly parallel, vertical, slightly curved, twice to three times as long as the shell.

Dimensions.—Shell 0.07 long, 0.09 broad; two sagittal spines 0.02 long, two lateral horns 0.04 long, two lateral feet 0.15 to 0.25 long.

Habitat.—Fossil in Barbados.

Subgenus 2. Triospyrium, Haeckel.

Definition.—Horns simple, not branched; feet forked or branched.

4. Triceraspyris furcata, Haeckel.

Ceratospyris furcata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 8.

Shell nut-shaped, tuberculate, with slight sagittal stricture. Pores numerous, irregular roundish. Basal plate with four large pores. Three horns small, conical, shorter than half the shell. Three feet large, cylindrical, curved, about twice as long as the shell, forked at the distal end.

Dimensions.—Shell 0.07 long, 0.08 broad; horns 0.02 long, feet 0.1 to 0.12 long.

Habitat.—Fossil in Barbados.

5. Triceraspyris giraffa, n. sp. (Pl. 84, fig. 11).

Shell nut-shaped, mammillate, with slight sagittal stricture. Pores numerous, subregular circular. Basal plate with nine pores (three larger central and three alternate pairs of smaller peripheral, as in Pl. 87, fig. 2). Three horns equal, straight, divergent, shorter than the shell, in the basal half cylindrical, in the distal half spindle-shaped. Three feet cylindrical, twice as long as the shell, nearly parallel, vertical, at the distal end divergent, with a recurved branch near the base.

Dimensions.—Shell 0.08 long, 0.1 broad; horns 0.05 to 0.07 long, feet 0.16 long.

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

6. Triceraspyris gazella, n. sp. (Pl. 84, fig. 9).

Shell nut-shaped, tuberculate, with sharp sagittal stricture. Pores large, irregular roundish; two or three pairs of larger pores on each side of the ring. Basal plate with three large triangular pores. Three horns simple, about as long as the shell, the apical straight, the two frontal elegantly curved. Three feet somewhat longer, slender, curved, with a recurved branch near the base, repeatedly forked at the distal end.

Dimensions.—Shell 0.06 long, 0.09 broad; horn 0.05 long, feet 0.08 long.

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

7. Triceraspyris corallorrhiza, n. sp. (Pl. 84, fig. 12).

Shell nut-shaped, spiny, with deep sagittal stricture. Pores irregular polygonal or roundish. Basal plate with two large semicircular pores. Three horns slender, simple, about half as long as the shell. Three feet of the same length, slender, divergent, irregularly branched like coral.

Dimensions.—Shell 0.06 long, 0.09 broad; horn and feet 0.03 to 0.05 long.

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

8. Triceraspyris maniculata, n. sp.

Shell subspherical, smooth, without external sagittal stricture. Pores subregular circular. Basal plate with four large pores (?). Three horns simple, straight, divergent, spindle-shaped, half as long as the shell. Caudal foot of the same form, twice as long. Two pectoral feet cylindrical, curved, twice as long as the shell, palmate, divided at the distal end into five short fingers.

Dimensions.—Shell 0.08 diameter; horns 0.04 long; lateral feet 0.12 long.

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

9. Triceraspyris longicornis, n. sp.

Shell nut-shaped, papillate, with deep sagittal stricture. Pores irregular roundish. Basal plate with six pores (?). Apical horn short, conical, two frontal horns very large, curved, widely divergent, longer than the shell. Three feet of about the same length, irregularly branched.

Dimensions.—Shell 0.08 long, 0.12 broad; lateral horns and feet 0.15 to 0.2 long.

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

Subgenus 3. Triospyridium, Haeckel.

Definition.—Horns and feet forked or branched.

10. Triceraspyris damaecornis, n. sp.

Shell nut-shaped, smooth, compressed, with broad sagittal ring. Pores irregular roundish; one pair of very large pores on each side of the ring. Basal plate with four large collar pores. Three horns and three feet short, divergent, slightly curved, about half as long as the shell, irregularly branched. (In general form very similar to Elaphospyris damaecornis, Pl. 84, fig. 10, with which I formerly confounded it.)

Dimensions.—Shell 0.08 long, 0.12 broad; horns and feet 0.04 long.

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

11. Triceraspyris arborescens, n. sp.

Shell subspherical, with deep sagittal stricture. Pores irregular roundish; three pairs of larger pores on both sides of the ring. Basal plate with two large collar pores. Three horns about half as long as the shell, with few irregular terminal branches. (Beginning of a cupola.) Three feet strong, cylindrical, twice as long as the shell, richly branched, arborescent.

Dimensions.—Shell 0.09 long, 0.1 broad; horns 0.05 long, feet 0.2 long.

Habitat.—Indian Ocean (Madagascar), Rabbe, surface.

Genus 443. Tristylospyris,^[3] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with three basal feet, without apical horn.

The genus Tristylospyris exhibits in general the same structure as the typical genus Tripospyris, its ancestral form. It differs from the latter in the absence of the apical horn, which is completely reduced, and may therefore be regarded as the simplest prototype of all tripodal Cyrtellaria without a horn.

Subgenus 1. Tristylospyrula, Haeckel.

Definition.—Feet simple, not branched nor forked.

1. Tristylospyris palmipes, n. sp. (Pl. 84, fig. 14).

Shell companulate, smooth, with slight sagittal stricture. Pores irregular roundish, three pairs of larger annular pores on each side of the broad ring. Basal plate with four large collar pores. Feet half as long as the shell, slightly divergent, straight, prismatic, with a broad, hand-like, radially striped plate at the distal end.

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

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

2. Tristylospyris scaphipes, n. sp. (Pl. 84, fig. 13).

Shell nut-shaped, smooth, with sharp sagittal stricture. Pores very small and numerous, circular; two pairs of larger pores on both sides of the ring. Basal plate with four large pores (?). Feet about half as long as the shell, angular, shovel-shaped, straight, parallel, vertical.

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

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

3. Tristylospyris clavipes, n. sp. (Pl. 84, fig. 15).

Shell nut-shaped, rough, with deep sagittal stricture. Pores small, subregular circular. Basal plate with three large pores. Feet about as long as the shell, slender, straight, divergent, with a spinulate knob at the thickened distal end.

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

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

4. Tristylospyris triceros, Haeckel.

Ceratospyris triceros, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xxi. fig. 5.

Shell nut-shaped, tuberculate, without external sagittal stricture. Pores circular, not numerous. Basal plate with four large collar pores. Feet large, cylindrical, three to four times as long as the shell, strongly curved and divergent.

Dimensions.—Shell 0.05 long, 0.07 broad; feet 0.15 to 0.2 long.

Habitat.—Fossil in Barbados.

Subgenus 2. Tristylospyrium, Haeckel.

Definition.—Feet forked or branched.

5. Tristylospyris furcata, n. sp.

Shell subspherical, rough, with slight sagittal stricture. Pores subregular circular. Basal plate with three large collar pores. Feet cylindrical, three to four times as long as the shell, strongly curved and divergent, at the distal end forked, with two short (sometimes ramified) branches.

Dimensions.—Cephalis 0.08 long, 0.09 broad; feet 0.2 to 0.3 long.

Habitat.—South Atlantic (off Patagonia), Station 318, surface.

6. Tristylospyris ramosa, n. sp. (Pl. 52, fig. 23).

Shell subspherical, tuberculate, with a prominent sagittal ring. Pores irregular roundish. Basal plate with three large pores. Feet large, straight, widely divergent, about twice as long as the shell, prismatic, irregularly branched. (Compare the following species.)

Dimensions.—Shell 0.08 in diameter; feet 0.15 long.

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

7. Tristylospyris tripodiscium, n. sp. (Pl. 52, fig. 22).

Shell subovate, tuberculate, very similar to the preceding species. It differs from this in the very different size of the irregular pores and the greater breadth of the pedal branches. The basal plate in a complete specimen (observed afterwards from the base) exhibited four large collar pores of the usual form, whilst in the similar preceding species it had three pores. In the similar Tripodiscium sphærocephalum (Pl. 52, fig. 21) the basal mouth is quite simple and open.

Dimensions.—Shell 0.09 long, 0.1 broad; feet 0.12 long.

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

Genus 444. Cephalospyris,^[4] Haeckel, 1881, Prodromus, p. 441 (sensu emend.).

Definition.—Zygospyrida with three basal feet and two large apical openings or coryphal holes, one on each side of the ring-apex. No true horns.

The genus Cephalospyris comprises some few Tripospyrida of very peculiar shape, differing from all other Zygospyrida in the possession of two large apical holes or coryphal apertures, lying on each side of a latticed sagittal septum, which is formed by the upper part of the sagittal ring. The sagittal stricture is deep, with a complete primary ring. The vertical axis of the slender ovate shell is much greater than the transverse. The network is very delicate, with very small and numerous triangular or polygonal pores. The central capsule encloses peculiar concrements (Pl. 96, fig. 28).

1. Cephalospyris cancellata, n. sp. (Pl. 83, fig. 10).

Shell slender ovate, two and a half times as long as broad, with deep sagittal stricture and complete ring. Network very delicate, with very small and numerous, irregular polygonal pores. The two large apical holes are separated by a latticed triangular sagittal septum, the apex of which represents a rudimentary horn. Basal plate with two large collar holes. Three feet slightly curved, divergent, about half as long as the breadth of the shell; the caudal foot slender, much thinner than the two stout pyramidal pectoral feet.

Dimensions.—Shell 0.32 long, 0.13 broad.

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

2. Cephalospyris ovata, n. sp.

Shell slender, ovate, twice as long as broad, with deep sagittal stricture and complete ring. Network very delicate, with very small and numerous triangular pores (on both poles intermingled with irregular polygonal pores). The two large apical holes are separated by a latticed triangular sagittal septum, the upper edge of which is concave and bears two rudimentary horns. Basal plate with four large collar holes. Three feet latticed, slightly curved, convergent, scarcely one-eighth as long as the breadth of the shell. The central capsule filled up by concrements.

Dimensions.—Shell 0.32 long, 0.16 broad.

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

3. Cephalospyris triangulata, n. sp. (Pl. 96, fig. 28).

Shell ovate, one and a half times as long as broad, with deep sagittal stricture and complete ring. Network very delicate and regular, with small triangular pores of equal size. The two large apical holes are separated by a latticed semilunar septum, the upper edge of which is concave, and bears two rudimentary horns. Basal plate with three large collar holes (?). Three feet latticed, conical, nearly parallel and vertical (the caudal curved), about half as long as the breadth of the shell. The ovate central capsule contains peculiar amyloidal concentric concrements.

Dimensions.—Shell 0.2 long, 0.14 broad.

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

Subfamily 2. Dipospyrida, Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida dipoda, with two descending lateral basal feet (probably corresponding to the pectoral feet of Cortina).

Genus 445. Dipospyris,^[5] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with two simple free basal feet and one apical horn.

The genus Dipospyris and the following five genera represent together the interesting subfamily of Dipospyrida, which always bear two opposite lateral feet only. Therefore in this bipedal group the biradial or bilateral type of the Spyroidea is particularly expressed. Such bipedal forms never occur in the Cyrtoidea. The topographical relation of the two lateral feet to the rods of the collar-plate, and to the cortinar pores separated by these, leaves no doubt that they correspond to the pectoral feet of Cortina and Tripospyris, and therefore that the Dipospyrida have originated from the Tripospyrida by loss of the caudal foot. Dipospyris is the simplest form of the Dipospyrida, with two simple free feet.

1. Dipospyris bipes, n. sp.

Shell thorax-shaped, smooth, with deep sagittal stricture, two vaulted bosoms, and subregular circular pores. Basal plate with two large collar pores only. Horn and feet equal, conical, straight, about as long as the shell; the feet widely divergent.

Dimensions.—Shell 0.08 long, 0.12 broad; horn and feet 0.1 to 0.15 long.

Habitat.—Fossil in Barbados.

2. Dipospyris mystax, Haeckel.

Ceratospyris mystax, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 6.

Shell elliptical spinulate, with slight collar stricture and large subregular circular pores. Basal plate with three pores (?) Horn small conical, oblique, shorter than the shell. Feet slender conical, longer than the shell, slightly curved, divergent. At the base of the columella, between the two feet, a small rudiment of the last caudal foot is visible.

Dimensions.—Shell 0.06 long, 0.1 broad; horn 0.02, feet 0.12 long.

Habitat.—Fossil in Barbados.

3. Dipospyris cubus, n. sp. (Pl. 83, fig. 18).

Shell box-shaped, subcubical, papillate, without external sagittal stricture, with numerous subregular circular pores. Basal plate with three very large collar pores, surrounded by a circle of smaller pores. Apical horn short and thick, scarcely half as long as the shell. Feet of the same form, longer than the shell, widely divergent.

Dimensions.—Shell 0.08 long, 0.11 broad; horn 0.03 long, feet 0.14 long.

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

4. Dipospyris chelifer, n. sp. (Pl. 85, fig. 3).

Shell elliptical, compressed, nodose, with deep sagittal stricture and irregular roundish pores. Basal plate with three pores (?). Apical horn stout, conical, twice to four times as long as the shell (often much longer than in the figured specimen). Feet scarcely longer then the shell, cylindrical, slightly curved towards one another.

Dimensions.—Shell 0.08 long, 0.12 broad; horn 0.2 to 0.3 long, feet 0.1 to 0.15 long.

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

5. Dipospyris irregularis, n. sp. Pl. 85, fig. 2.

Shell subspherical, without external sagittal stricture, with small circular pores. Basal plate with four pores. Apical horn small, conical, shorter than the shell. Feet three to four times as long as the shell, cylindrical, irregularly curved, very variable in size and form.

Dimensions.—Shell 0.08 long, 0.1 broad; horn 0.02 to 0.04 long, feet 0.2 to 0.3 long.

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

6. Dipospyris sigmopodium, n. sp.

Shell violin-shaped, thorny, with deep sagittal stricture and irregular roundish pores. Basal plate with four collar pores. Horn straight, conical, about as long as the shell. Feet twice as long, cylindrical, markedly divergent, S-shaped, curved.

Dimensions.—Shell 0.08 long, 0.12 broad; horn 0.06 long, feet 0.2 long.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms; also fossil in Barbados.

7. Dipospyris forcipata, n. sp. (Pl. 85, fig. 1).

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate with four larger and a circle of six to ten smaller pores. Horn cylindrical, straight, two to three times as long as the shell. Feet three to five times as long as the shell, cylindrical, semicircular, with convergent and crossed distal ends. (If these ends grow together, Gamospyris arises.)

Dimensions.—Shell 0.08 long, 0.11 broad; horn 0.15 to 0.2 long, feet 0.2 to 0.4 long.

Habitat.—Central Pacific, Stations 263 to 268, depth 2600 to 3000 fathoms.

Genus 446. Brachiospyris,^[6] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with two simple free basal feet, without apical horn.

The genus Brachiospyris differs from the preceding Dipospyris, its ancestral form, only in the absence of the reduced apical horn, and therefore bears to it a similar relation to that which the hornless Tristylospyris, among the Tripospyrida, bears to the horned Tripospyris. Brachiospyris may therefore also be derived from Tristylospyris by loss of the caudal foot.

1. Brachiospyris ocellata, Haeckel.

Ceratospyris ocellata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 5.

Shell nut-shaped, thorny, with slight sagittal stricture and irregular roundish pores. Basal plate with four large and four alternate pairs of smaller pores. Two feet cylindrical, straight, divergent, two to three times as long as the shell.

Dimensions.—Shell 0.08 long, 0.11 broad; feet 0.2 to 0.3 long.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms; also fossil in Barbados.

2. Brachiospyris diacantha, n. sp. (Pl. 95, fig. 5).

? Ceratospyris diacantha, Ehrenberg, 1872, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 303.

Shell nut-shaped, tuberculate, compressed in the sagittal axis, convex on the frontal face, concave on the sagittal face, with a slight sagittal stricture; with large irregular roundish pores. Basal plate with three very large pores. Two feet cylindrical, curved, S-shaped, about twice as long as the shell.

Dimensions.—Shell 0.06 long, 0.09 broad; feet 0.1 to 0.15 long.

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

Genus 447. Dendrospyris,^[7] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with two free lateral feet, forked or branched like a tree. Apex with a horn.

The genus Dendrospyris differs from its ancestral form Dipospyris in the ramification of the two large lateral feet, which descend from the base of the shell, and are usually very large and stout, sometimes simply forked.

1. Dendrospyris stylophora, Haeckel.

Ceratospyris stylophora, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 10.

Shell nut-shaped, thorny, with subregular circular pores. Basal plate with four pores. Apical horn and the two divergent feet straight, cylindrical, larger than the shell, forked at the distal end. (The size and number of the fork-branches is variable; the horn is sometimes simple. In some specimens a rudimentary remnant of the lost caudal foot is visible.)

Dimensions.—Shell 0.08 long, 0.09 broad; horn and feet 0.1 to 0.12 long.

Habitat.—Fossil in Barbados.

2. Dendrospyris dirrhiza, Haeckel.

Ceratospyris dirrhiza, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 9.

Shell nut-shaped, spiny, very similar to the preceding species. It differs from that mainly in the growth of the cylindrical feet, which are not straight and divergent, but more or less curved and convergent; their distal ends are sometimes simply forked, sometimes repeatedly dichotomous. The size and form of the apical horn are also very variable.

Dimensions.—Shell 0.06 long, 0.08 broad; horn and feet 0.07 to 0.09 long.

Habitat.—Fossil in Barbados.

3. Dendrospyris bibrachiata, Haeckel.

Cladospyris bibrachiata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xxi. fig. 7.

Shell nut-shaped, smooth, with sharp stricture and numerous very small circular pores. Apical horn and the two feet very large and stout, straight, prismatic, with irregular lateral branches on their edges, twice to four times as long as the shell (The horn in the Ehrenberg's figure is broken off.) This species is closely allied to Tripospyris tribrachiata.

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

Habitat.—Fossil in Barbados.

4. Dendrospyris furcata, n. sp.

Shell subspherical, tuberculate, with irregularly roundish pores. Basal plate with two large pores. Apical horn simple, conical, as long as the shell. Feet cylindrical, twice as long, in the proximal half parallel, vertical, in the distal half with two stout divergent equal fork-branches, one of which is directed dorsally, the other ventrally.

Dimensions.—Shell 0.07 long, 0.08 broad; horn 0.06 long, feet 0.1 to 0.15 long.

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

5. Dendrospyris polyrrhiza, n. sp. (Pl. 85, fig. 8).

Shell subspherical, rough, with subregular circular pores. Basal plate with three pores (?). Apical horn simple, conical, half as long as the shell. Feet cylindrical twice to three times as long as the shell, semicircular, with a strong conical tooth in the middle of their outer convex edge; their distal ends convergent, divided into a bunch of numerous short irregular branches.

Dimensions.—Shell 0.7 long, 0.08 broad; horn 0.03 long, feet 0.15 to 0.25 long.

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

6. Dendrospyris ramosa, n. sp.

Shell nut-shaped, spiny, with irregular roundish pores. Basal plate with three pairs of pores. Apical horn cylindrical, spinulate, twice to three times as long as the shell. Feet as long as the horn, S-shaped, widely divergent, irregularly branched, with widely distant pointed branches.

Dimensions.—Shell 0.08 long, 0.12 broad; horn and feet 0.2 to 0.3 long.

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

7. Dendrospyris arborescens, n. sp. (Pl. 85, fig. 9).

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate with four central larger and ten to twelve peripheral smaller pores. Apical horn cylindrical, twice as long as the shell, in the distal half spinulate or tuberculate. Feet about three times as long as the shell, cylindrical, nearly vertical, in the distal half irregularly branched, with dense bunches of aggregated blunt branches.

Dimensions.—Shell 0.07 long, 0.09 broad; horn and feet 0.12 to 0.18 long.

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

Genus 448. Dorcadospyris,^[8] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with two free lateral feet armed with a series of secondary spines. Apex with a horn.

The genus Dorcadospyris and the closely allied Stephanospyris differ from the other Dipospyrida in the development of a series of secondary spines on the convex outer margin of the two large curved lateral feet, which therefore appear semipinnate. In some species this peculiar armature attains an extraordinary size, whilst the shell itself is very small, as in Dorcadospyris dinoceras (Pl. 85, fig. 4).

1. Dorcadospyris dentata, n. sp. (Pl. 85, fig. 6).

Shell subspherical, tuberculate with small regular circular pores. Basal plate with four larger pores. Apical horn three to four times as long as the shell, slender conical, smooth. Feet more or less convexly curved towards one another; the distal ends not crossed. In the convex edge of each arm a series of five to ten smooth conical teeth, not longer than the shell. This common species is very variable and often asymmetrical; the figured specimen is an asymmetrical one, in which the two arms exhibit different curves; in the normal form both arms have the same curve, now more, now less convex.

Dimensions.—Shell 0.06 long, 0.08 broad; horn 0.2, feet 0.03 long.

Habitat.—Central Pacific, Stations 267 to 274, depth 2350 to 2925 fathoms.

2. Dorcadospyris antilope, n. sp. (Pl. 85, fig. 5).

Shell subspherical, tuberculate, with small regular circular pores. Basal plate with four larger pores. Apical horn four to six times as long as the shell, straight, cylindrical, smooth. Feet of the same length, crescentic or nearly semicircular, with crossed distal ends. On the convex edge of each foot a series of twelve to fifteen smooth conical teeth, partly longer than the shell. (Very variable in size and curvature of the feet, and number of their teeth.)

Dimensions.—Shell 0.09 long, 0.11 broad; horn and feet 0.4 to 0.6 long.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

3. Dorcadospyris lunulata, n. sp.

Shell subspherical spinulate, nearly of the same shape as in the preceding species, but with a short conical horn (scarcely as long as the shell); the feet are much mere slender, crescentic, and bear twenty to thirty smaller smooth conical teeth (shorter than the shell). The distal ends of the feet are crossed.

Dimensions.—Shell 0.08 long, 0.09 broad; horn 0.06 long, feet 0.03 to 0.06 long.

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

4. Dorcadospyris decussata, n. sp. (Pl. 85, fig. 7).

Shell subspherical, smooth, very similar to that of the two preceding species. Horn small conical, about as long as the shell. Feet more than semicircular, more strongly curved than in any other species, each with four to eight small conical teeth, shorter than the shell; distal ends crossed. (In this species also, besides the normal symmetrical form, there often occurs an asymmetrical form of the two feet; one of these frequent anomalies is shown in fig. 7.)

Dimensions.—Shell 0.06 long, 0.08 broad; horn 0.05, feet 0.2 to 0.5 long.

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

5. Dorcadospyris dinoceras, n. sp. (Pl. 85, fig. 4).

Shell subspherical, tuberculate, with subregular circular pores. Basal plate with four larger central and eight to twelve smaller peripheral pores. Horn about as long as the shell, in the basal half prismatic, smooth, in the distal half ovate or strobiliform, spiny. Feet very large and strongly curved, together nearly heart-shaped, four to six times as long as the shell. Each foot bears on its outer convex side a series of fifteen to twenty or more strong conical teeth, which are again spinulate, perpendicular to the foot, and longer than the shell.

Dimensions.—Shell 0.08 long, 0.09 broad; horn 0.07 long, feet 0.3 to 0.5 long.

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

Genus 449. Gamospyris,^[9] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with two simple lateral feet, forming a ring by union.

The genus Gamospyris and the similar Stephanospyris differ from all other Spyroidea in the possession of a large basal ring, placed in the frontal plane of the shell. This ring has been produced by concrescence of the distal ends of the two large curved lateral feet of Dipospyris.

1. Gamospyris circulus, n. sp. (Pl. 83, fig. 19).

Shell subspherical, tuberculate, with subregular circular pores. Basal plate with four larger collar pores. Apical horn pyramidal, about as long as the shell. The connected feet form together a circular or nearly circular smooth ring, the diameter of which is three to four times as great as that of the shell.

Dimensions.—Shell 0.08 long, 0.09 broad; diameter of the arm-ring 0.25 to 0.33.

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

2. Gamospyris annulus, n. sp.

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate with four large central and a circle of eight to twelve small peripheral pores. Apical horn conical, twice as long as the shell. The connected arms form together an elliptical smooth ring, which is five times as long and three times as broad as the shell.

Dimensions.—Shell 0.07 long, 0.09 broad; ring 0.33 long, 0.26 broad.

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

Genus 450. Stephanospyris,^[10] Haeckel, 1881, Prodromus, p. 441.

Definition.—Zygospyrida with two lateral feet bearing a series of secondary spines and forming a ring by union.

The genus Stephanospyris exhibits the same peculiar armature of the semipinnate lateral feet as its ancestral genus Dorcadospyris, but differs from it in the concrescence of the distal ends of the feet, to form a complete foot-ring. The former therefore bears to the latter the same relation that Gamospyris does to Dipospyris.

1. Stephanospyris cordata, n. sp. (Pl. 85, fig. 10).

Shell subspherical, tuberculate, with small regular circular pores. Basal plate with four larger pores. Apical horn cylindrical, three times as long as the shell, with three to four verticils of teeth. The connected feet form a heart-shaped ring, four times as long and three times as broad as the shell. Each foot bears on the outer convex edge four to six stout conical teeth, shorter than the shell. Distal ends crossed and prominent.

Dimensions.—Shell diameter 0.1; length of the arm-ring 0.4, breadth 0.3.

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

2. Stephanospyris verticillata, n. sp. (Pl. 85, fig. 11).

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate with numerous small pores. Apical horn cylindrical, four to six times as long as the shell, with six to ten verticils of teeth. The connected feet form a circular ring, the diameter of which is four times as great as that of the shell. Each foot bears ten to twelve conical teeth, about as long as the shell. Distal ends not crossed and not prominent.

Dimensions.—Diameter of the shell 0.1, of the arm-ring 0.4.

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

3. Stephanospyris excellens, n. sp. (Pl. 83, fig. 20).

Shell subspherical, tuberculate, with regular circular pores. Basal plate with numerous small pores. Apical horn cylindrical, twice as long as the shell, with eight verticils of teeth. The connected feet form an ovate ring, which is three times as long and two and a half times as broad as the shell. Each foot bears eight conical spinulate teeth, about as long as the shell. The crossed and prominent distal ends bear two parallel vertical teeth.

Dimensions.—Diameter of the shell 0.1, of the arm-ring 0.2 to 0.3.

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

Subfamily 3. Tetraspyrida, Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida tetrapoda, with four descending basal feet, two of which are opposite in the sagittal plane (an odd caudal and an odd sternal foot), whilst the two others are paired lateral or pectoral feet.

Genus 451. Tetraspyris,^[11] Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida with four basal feet crossed in pairs (two sagittal and two lateral). Apex with a horn.

The genus Tetraspyris and the following closely allied Tessarospyris represent together the small subfamily of Tetraspyrida, characterised by the possession of four descending basal feet, three of which correspond to the three original feet of the ancestral genera Cortina and Tripospyris, whilst the fourth in an odd anterior or sternal foot, produced by anterior prolongation of the basilar segment of the sagittal ring. Here, therefore, two opposed feet lie in the sagittal plane (a caudal and a sternal foot), whilst the two others are the paired lateral or pectoral feet, as also in Stephanium and Stephaniscus, p. 965. The Tetraspyrida ought not to be confounded with the Therospyrida (sixth subfamily), in which the four feet have another signification.

Subgenus 1. Tetrarrhabda, Haeckel, 1881, p. 429.

Definition.—Feet simple, not branched nor forked.

1. Tetraspyris stephanium, n. sp. (Pl. 95, fig. 6).

Shell nut-shaped, tuberculate, with deep sagittal stricture and small roundish pores; three pairs of larger pores on each side of the ring. Basal plate with four large collar pores. Apical horn stout conical, half as long as the shell. Two pectoral feet somewhat longer than the two sagittal feet, one and a half times as long as the shell. All four feet straight, three-sided prismatic, strongly divergent.

Dimensions.—Shell 0.08 long, 0.12 broad; horn 0.04 long, feet 0.08 to 0.12 long.

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

2. Tetraspyris cubica, n. sp.

Shell nearly cubical, smooth, with slight sagittal stricture and small polygonal pores; some larger pores on both sides of the ring. Basal plate with four large collar pores. Apical horn and the four feet of equal size and form, about as long as the shell, cylindrical in the basal, spindle shaped in the distal half.

Dimensions.—Shell 0.09 diameter; horn and feet 0.1 long.

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

Subgenus 2. Tetracorethra, Haeckel, 1831, Prodromus, p. 429.

Definition.—Feet branched or forked.

3. Tetraspyris tetracorethra, n. sp. (Pl. 53, figs. 19, 20).

Tetracorethra mirabilis, Haeckel, 1881, Prodromus, p. 439, and Atlas, loc. cit.

Shell campanulate, tuberculate, with deep sagittal stricture and irregular polygonal pores; two pairs of larger pores at the flattened occipital face (fig. 20). Basal plate with four large collar pores. Apical horn very long, thirty to forty times as long as the shell, slender three-sided prismatic, straight, at the distal end irregularly branched, besom-shaped. Four basal feet half as thick as the horn, eight to twelve times as long as the shell, bristle-shaped, irregularly curved and branched, divergent, at the distal end besom-shaped. Central capsule very large; the enclosed small campanulate part sends out through the four collar pores four very long club-shaped basal lobes, half as long as the feet; each lobe contains a large oil-globule (fig. 19).

Dimensions.—Shell 0.036 diameter; horn 1 to 1.5 mm. long, feet 0.3 to 0.4 long.

Habitat.—Central Pacific, Station 270, surface.

4. Tetraspyris calcarata, n. sp.

Shell campanulate, smooth, very similar to that of the preceding species, but differing in the following characters:—the two inferior occipital pores are four times (in the preceding twice) as large as the two superior; the apical horn bears at its distal end only three simple branches; the sternal foot is smaller than the three others, arises higher, is more divergent and curved, and bears at its base a large horizontal conical spur.

Dimensions.—Shell 0.035 diameter; horn 1 to 1.2 long, feet 0.2 to 0.3 long.

Habitat.—Central Pacific, Station 266, surface.

5. Tetraspyris scoparia, n. sp.

Shell campanulate, rough, very similar to the two preceding species, but differing in the following characters:—the four occipital pores are of nearly equal size; the apical horn is simple, not branched; the four feet are forked near the base, so that apparently eight feet diverge, each in the distal half richly branched, besom-shaped.

Dimensions.—Shell 0.038 diameter; horn 1 to 1.1 long, feet 0.4 to 0.5 long.

Habitat.—Central Pacific, Station 268, surface.

Genus 452. Tessarospyris,^[12] Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida with four basal feet crossed in pairs (two sagittal and two lateral). Apex without horn.

The genus Tessarospyris differs from the preceding Tetraspyris, its ancestral genus, in the absence of the apical horn, and therefore bears to it the same relation that Tristylospyris does to Tripospyris.

1. Tessarospyris clathrobursa, n. sp. (Pl. 53, fig. 8).

Clathrobursa dictyopus, Haeckel, 1881, Prodromus, p. 439, and Atlas, pl. liii. fig. 8.

Shell nearly ovate, strongly compressed, smooth, one and a half times as long as broad, with deep sagittal stricture in the basal half. Pores very small and numerous, irregularly roundish. Basal plate with four very large triangular holes, two larger (posterior) cardinal, and two smaller (anterior) jugular pores; above the latter (on the frontal face) two large mental pores. Two pectoral feet large, half as long as the shell, at the base fenestrated, vertical, and parallel. Two sagittal feet much smaller, nearly horizontal, pyramidal (the caudal larger than the sternal foot). Two longitudinal pectoral ribs arise on the frontal face.

Dimensions.—Shell 0.21 long, 0.14 broad; lateral feet 0.1, sagittal feet 0.02.

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

2. Tessarospyris nuciformis, n. sp.

Shell nut-shaped, papillate, with deep sagittal stricture. Pores irregular roundish, on both sides of the ring three to six times as large as on the lateral sides. Basal plate with four large pores. Two pectoral feet cylindrical curved, twice as long as the shell and as the two sagittal feet; the caudal is much stronger than the sternal foot.

Dimensions.—Shell 0.06 long, 0.09 broad; lateral feet 0.1, sagittal feet 0.05 long.

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

3. Tessarospyris seminulum, Haeckel.

Petalospyris seminulum, Stöhr, 1880, Palæontogr., vol. xxvi. pl. iii. fig. 12.

Shell subspherical, smooth, with slight sagittal stricture and small circular pores; some larger pores on both sides of the ring. Basal plate with two large (lateral) pores only. Four feet nearly equal, short, conical, divergent, scarcely one-fourth as long as the shell.

Dimensions.—Shell 0.06 long, 0.08 broad; feet 0.016 long.

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

Subfamily 4. Hexaspyrida, Haeckel.

Definition.—Zygospyrida hexapoda, with six descending basal feet; three of these are primary (one odd caudal and two paired pectoral feet), the other three are secondary, opposed diametrically to the former and alternating with them (one odd sternal and two paired tergal feet).

Genus 453. Hexaspyris,^[13] n. gen.

Definition.—Zygospyrida with six basal feet and one apical horn.

The genus Hexaspyris and the two following closely allied genera represent together the peculiar subfamily of Hexaspyrida, and differ from the other Zygospyrida in the possession of six descending basal feet; three of these are the three original, perradial, or primary basal feet of Cortina, Cortiniscus, Plagoniscus, Plectaniscus, Tripospyris, &c.; the other three, usually opposed to the former diametrically, are secondary or interradial; an odd sternal foot (opposed to the odd caudal) and two paired tergal feet (opposed to the two paired pectoral).

Subgenus 1. Hexaspyridium, Haeckel.

Definition.—Feet simple, not branched nor forked.

1. Hexaspyris alterna, n. sp.

Shell nut-shaped, smooth, with deep sagittal stricture and irregular polygonal pores; on each side of the stricture two pairs of larger square annular pores. Basal plate also with four larger collar pores. Apical horn twice as long as the shell, conical. Three primary feet (the apical and the two pectoral) slender, curved, as long as the horn; three secondary feet (the sternal and the two tergal) are half as long as the former and more highly inserted; all six feet strongly divergent, cylindrical, pointed.

Dimensions.—Shell 0.06 long, 0.09 broad; horn 0.15 long, feet 0.08 to 0.14 long.

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

2. Hexaspyris setigera, Haeckel.

Ceratospyris setigera, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 11. Ceratospyris setigera, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxii. figs. 11a, 11b.

Shell nut-shaped, tuberculate, with a complete internal sagittal ring and numerous small circular pores. Basal plate with four larger central and a circle of twelve to twenty smaller peripheral pores. Apical horn half as long as the shell, bristle-shaped. Three primary feet longer and more deeply inserted than the three secondary feet; all six feet strongly divergent, bristle-shaped, shorter than the shell.

Dimensions.—Shell 0.06 long, 0.09 broad; horn 0.03 long; primary feet 0.05, secondary 0.02 long.

Habitat.—Fossil in Barbados.

3. Hexaspyris bütschlii, Haeckel.

Ceratospyris triomma, Bütschli (non Ehrenberg), 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxii. fig. 12, a, b.

Shell nut-shaped, spinulate, with a complete internal sagittal ring and subregular circular pores. Basal plate with twelve pores (four larger central and eight smaller peripheral). Apical horn stout, oblique, as long as the shell. Six feet of equal length, slightly divergent, nearly vertical, slender, three to four times as long as the shell.

Dimensions.—Shell 0.05 long, 0.07 broad; horn 0.06, feet 0.15 to 0.2 long.

Habitat.—Fossil in Barbados.

4. Hexaspyris spinosa, Haeckel.

Petalospyris spinosa, Stöhr, 1880, Palæontogr., vol. xxvi. p. 98, Taf. iii. fig. 14.

Shell subspherical, smooth, with slight sagittal stricture and irregular polygonal pores; on each side of the stricture two pairs of larger pores. Basal plate with two large pores only. Apical horn short, pyramidal, three primary feet half as long as the shell and twice as long as the three secondary feet. All six feet pyramidal, slightly divergent.

Dimensions.—Shell 0.05 long, 0.07 broad; horn 0.02, feet 0.02 to 0.04 long.

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

5. Hexaspyris ophirensis, Haeckel.

Petalospyris ophirensis, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. ix. fig. 24.

Shell nut-shaped, with deep sagittal stricture and numerous irregular roundish pores; two pairs of larger pores on each side of the stricture. Apical horn short, curved. Six feet equal, divergent, straight, slender, about as long as the shell.

Dimensions.—Shell 0.05 long, 0.1 broad; horn 0.01, feet 0.05 to 0.08 long.

Habitat.—Indian Ocean (Zanzibar), depth 2200 fathoms, Pullen.

Subgenus 2. Hexacorethra, Haeckel.

Definition.—Feet forked or branched.

6. Hexaspyris hexacorethra, n. sp. (Pl. 95, fig. 8).

Hexacorethra magica, Haeckel, 1882, Manuscript.

Shell campanulate, smooth, with sharp sagittal stricture and irregular roundish pores. Basal plate with six larger collar pores. Apical horn very long and thin, three-sided prismatic, straight, ten to twenty times as long as the shell, branched at the distal end. Six feet thinner, bristle-shaped, six to eight times as long as the shell, divergent, irregularly curved, in the distal part branched, besom-shaped; the sternal foot at its base with a large conical horizontal spur.

Dimensions.—Shell 0.034 diameter; horn 0.4 to 0.8 long, feet 0.2 to 0.3 long.

Habitat.—Central Pacific, Station 265, surface.

7. Hexaspyris articulata, Haeckel.

Ceratospyris articulata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 4.

Shell nut-shaped, tuberculate, with deep sagittal stricture and small irregular roundish pores. Basal plate with six pores (?). Apical horn conical, longer than the shell. Six feet very large, thick cylindrical, divergent, three to four times as long as the shell, with few irregular lateral branches (often much more developed than in Ehrenberg's figure).

Dimensions.—Shell 0.036 long, 0.05 broad; horn 0.05, feet 0.1 to 0.15 long.

Habitat.—Fossil in Barbados.

Genus 454. Liriospyris,^[14] Haeckel, 1881, Prodromus, p. 443.

Definition.—Zygospyrida with six basal feet and three coryphal horns.

The genus Liriospyris differs from the preceding Hexaspyris, its ancestral form, in the possession of three coryphal horns (one odd apical in the middle, and two paired frontal horns on each side of it); it therefore bears to the latter the same relation that Triceraspyris does to Tripospyris.

1. Liriospyris hexapoda, n. sp. (Pl. 86, fig. 7).

Shell subspherical, smooth, with slight sagittal stricture and irregular roundish pores; two to three pairs of large annular pores on each side of the stricture. Basal plate with four large collar pores. Three horns and six feet nearly of the same size and of similar form, conical, divergent, about one-third as long as the shell.

Dimensions.—Shell diameter 0.09 to 0.1; horns and feet 0.03 to 0.04 long.

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

2. Liriospyris clathrata, Haeckel.

Dictyospyris clathrus, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 25.

Dictyospyris clathrata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xix. fig. 7.

Dictyospyris clathrata, Bütschli, 1882, Zeitschr. f. Wiss. Zool., vol. xxxvi. pp. 506, 539; Taf. xxxii. figs. 10a, 10b.

Petalospyris clathrus, Haeckel, 1862, Monogr. d. Radiol., p. 295.

Shell campanulate or nearly spherical, smooth, with slight sagittal stricture. Three pairs of large annular pores on each side of the stricture; a few smaller irregular pores on the lateral sides. Basal plate with six large collar pores (Bütschli, loc. cit., fig. 10a). Three horns and six feet nearly of the same size and form; short, conical, slightly divergent or nearly parallel, shorter than half the ring. (The size of the nine appendages is in this common species rather variable; sometimes they are rudimentary, at other times much stronger than in the good figure of Bütschli.)

Dimensions.—Shell diameter 0.08 to 0.09, horns and feet 0.01 to 0.03.

Habitat.—Cosmopolitan; Mediterranean, Atlantic, Pacific; also fossil in Barbados and Sicily.

3. Liriospyris heteropoda, n. sp.

Shell nut-shaped, nodose, with deep sagittal stricture and small circular pores; two pairs of larger pores on each side of the stricture. Basal plate with four larger central and eight smaller peripheral pores. Apical horn conical, as long as the shell and twice as long as the two curved frontal horns. Three primary feet twice as long as the shell and as the three secondary feet, which are more highly inserted. All six feet slender curved, divergent.

Dimensions.—Shell 0.07 long, 0.11 broad; horn and secondary feet 0.08 long, primary feet 0.15 long.

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

4. Liriospyris turrita, Haeckel.

Ceratospyris turrita, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 1.

Shell ovate, campanulate, smooth, with sharp sagittal stricture and irregular roundish pores; three to four pairs of larger pores on each side of the stricture. Basal plate with four large collar pores. Three horns short and stout, conical, fenestrated at the base. Six feet slender, conical, nearly vertical, of equal size, only one-third as long as the shell.

Dimensions.—Shell 0.08 long, 0.06 broad; horns 0.01 long, feet 0.03 long.

Habitat.—Fossil in Barbados.

5. Liriospyris amphithecta, n. sp. (Pl. 95, fig. 7).

Shell nut-shaped, tuberculate, with distinct sagittal stricture and irregular roundish pores. Basal plate with six larger and twelve smaller pores. Three horns conical, the apical as long as the shell and twice as long as the curved frontal horns. Two pectoral feet cylindrical, very large, curved, divergent, about three times as long as the shell and as the four other feet, which are conical.

Dimensions.—Shell 0.08 long, 0.12 broad; apical horn 0.08, frontal horns 0.05 long; length of the two pectoral feet 0.2, of the four others 0.06.

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

Genus 455. Cantharospyris,^[15] n. gen.

Definition.—Zygospyrida with six basal feet, without apical horn.

The genus Cantharospyris differs from the preceding two hexapodal genera in the absence of horns on the coryphal face, and has therefore the same relation to them that the hornless Tristylospyris bears to the one-horned Tripospyris and the three-horned Triceraspyris.

1. Cantharospyris carabus, n. sp.

Shell nut-shaped, with deep sagittal stricture and irregular roundish pores. Basal plate with six larger pores. Six feet of different sizes, cylindrical, curved; three primary feet (one caudal and two pectoral) about as long as the shell and twice as long as the three secondary feet.

Dimensions.—Shell 0.08 long, 0.12 broad; feet 0.05 to 0.09 long.

Habitat.—Tropical Atlantic, Station 338, depth 1990 fathoms; Central Pacific, Station 268, depth 2900 fathoms.

2. Cantharospyris ateuchus, Haeckel.

Ceratospyris ateuchus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xxi. fig. 4.

Shell nut-shaped, tuberculate, with slight sagittal stricture and unequal circular pores. Basal plate with six larger pores. The two pectoral feet very large and stout, four to six times as long as the shell, widely divergent, curved. The four other feet much smaller and thinner, about as long as the shell.

Dimensions.—Shell 0.06 long, 0.08 broad; length of the two larger feet 0.2 to 0.3, of the four smaller 0.05 to 0.07.

Habitat.—Fossil in Barbados.

3. Cantharospyris radicata, Haeckel.

Ceratospyris radicata, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 43; Mikrogeol., 1854, Taf. xxii. fig. 37.

Haliomma radicatum, Ehrenberg, 1844, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 83.

Petalospyris radicata, Haeckel, 1862, Monogr. d. Radiol., p. 295.

Petalospyris radicata, Stöhr, 1880, Palæontogr., vol xxvi. p. 79, Taf. iii. fig. 11.

Shell nut-shaped, smooth, with slight sagittal stricture and irregular roundish pores; two larger pores on each side of the ring. Basal plate with six pores (?). Six feet of equal size and similar form, conical, divergent, slightly curved, shorter than half the ring.

Dimensions.—Shell 0.05 long, 0.08 broad; feet 0.02 long.

Habitat.—Fossil in Barbados and Sicily.

4. Cantharospyris platybursa, n. sp. (Pl. 53, fig. 7).

Platybursa compressa, Haeckel, 1881, Prodromus, p. 429; Atlas, pl. 53, fig. 7.

Shell smooth, nearly discoidal circular, markedly compressed in the sagittal direction, with slight basal stricture. Pores very numerous, irregular polygonal, with thin bars. Basal plate with four very large pores. Six feet short, conical, nearly horizontally expanded. Two sagittal feet (caudal and sternal) larger, about half as long as the shell (shortened in the figure). The two sternal feet larger than the two small or rudimentary tergal feet.

Dimensions.—Shell 0.15 long, 0.13 broad; feet 0.02 to 0.06 long.

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

Subfamily 5. Pentaspyrida, Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida pentapoda, with five descending basal feet, one odd caudal foot, and two pairs of lateral feet (two anterior or pectoral, and two posterior or tergal feet).

Genus 456. Clathrospyris,^[16] Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida with five basal feet and one apical horn.

The genus Clathrospyris and the two following closely allied genera represent together the small subfamily of Pentaspyrida, differing from the other Zygospyrida in the possession of five descending feet on the basal face. Three of these are the primary cortinar feet (of Cortiniscus, Plagoniscus, Tripospyris, &c.), whilst the two others are secondary tergal feet. The Pentaspyrida may therefore be probably derived from the Hexaspyrida by loss of the odd anterior or sternal foot.

1. Clathrospyris camelopardalis, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores irregular roundish. Basal plate with six pores (?). Two pectoral feet very large, twice as long as the shell, cylindrical, curved. Two tergal feet half as long and thick as the pectoral. Caudal foot and apical horn straight, conical, half as long as the shell.

Dimensions.—Shell 0.07 long, 0.09 broad; horn and odd caudal foot 0.04 long; pectoral feet 0.16, tergal 0.08 long.

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

2. Clathrospyris pyramidalis, n. sp. (Pl. 95, fig. 9).

Shell four-sided pyramidal, truncate, thorny, with a slight sagittal stricture. Pores very large, polygonal roundish. Two pairs of large pores on each side of the ring (at the frontal and the occipital plate). Lateral pores more numerous. Basal plate with four large pores. The four edges of the pyramid are prolonged into four short pyramidal divergent lateral feet (one-third as long as the shell). Caudal foot short. Horn at the apex of the truncate pyramid with two lateral teeth.

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

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

3. Clathrospyris fusiformis, n. sp.

Shell nearly cubical, smooth, with slight sagittal stricture. Pores roundish; three pairs of larger pores on each side of the ring. Basal plate with six large pores. Five feet of equal length, slender, spindle-shaped, about as long as the shell, divergent. Apical horn conical, and half as long as the feet.

Dimensions.—Shell 0.08 long, 0.09 broad; horn 0.05 long, feet 0.1 long.

Habitat.—Fossil in Barbados.

Genus 457. Aegospyris,^[17] Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida with five basal feet and three coryphal horns.

The genus Aegospyris differs from the preceding Clathrospyris, its ancestral form, in the possession of three horns on the coryphal face (one odd apical, and two paired frontal horns on each side), and therefore bears to the latter the same relation that Triceraspyris does to Tripospyris, and Liriospyris to Hexaspyris.

1. Aegospyris aequispina, n. sp.

Shell nut-shaped, tuberculate, with slight sagittal stricture. Pores subregular circular. Basal plate with four large collar pores. Three horns and five feet all of equal size and similar form, slender conical, slightly curved, widely divergent, about as long as the shell.

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

Habitat.—Central Pacific, Stations 265 to 274, depth 2350 to 2925 fathoms.

2. Aegospyris octospina, n. sp.

Shell nearly cubical, smooth, with slight sagittal stricture. Pores subregular circular; two pairs of larger pores on each side of the ring. Basal plate with four large pores. Two paired horns and four paired feet of equal size and similar form, S-shaped curved, twice as long as the shell. Odd horn and odd feet half as long, straight, conical.

Dimensions.—Shell 0.08 long, 0.09 broad; six paired spines 0.2 long, two odd spines 0.1 long.

Habitat.—South Atlantic, Station 323, depth 1900 fathoms.

3. Aegospyris longibarba, Haeckel.

Ceratospyris longibarba, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xxi. figs. 1, 2.

Shell nut-shaped, tuberculate, with slight sagittal stricture. Pores subregular circular. Basal plate with four larger central, and eight smaller peripheral pores. Apical horn and caudal foot short, straight, conical; two frontal horns longer, curved; four paired feet slender, curved, twice as long as the shell.

Dimensions.—Shell 0.06 long, 0.08 broad; paired horns 0.03 long, paired feet 0.1 long.

Habitat.—Fossil in Barbados.

4. Aegospyris aegoceras, n. sp. (Pl. 95, fig. 10).

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores irregular roundish. Basal plate with three large pores. Apical horn and caudal foot short, straight, spindle-shaped; two frontal horns as long as the shell, strongly curved; four paired feet also curved, at the distal end forked, divergent; the tergal thinner and as long as the shell, the pectoral thicker and twice as long.

Dimensions.—Shell 0.07 long, 0.09 broad; pectoral feet 0.1 long.

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

5. Aegospyris caprina, n. sp. (Pl. 86, fig. 8).

Shell nut-shaped, papillate, with sharp sagittal stricture. Pores irregular roundish, two pairs of larger pores on each side of the ring. Basal plate with six large pores. Eight spines all straight, subvertical and nearly parallel, cylindro-conical. Two frontal horns and two tergal feet about as long as the shell; odd horn shorter; odd foot longer. Two pectoral feet twice as long as the shell, club-shaped, with a spinulate knob at the distal end.

Dimensions.—Shell 0.06 long, 0.09 broad; pectoral feet 0.11 long.

Habitat.—Central Pacific, Station 271, surface.

Genus 458. Pentaspyris,^[18] Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida with five basal feet, without apical horn.

The genus Pentaspyris differs from the two preceding genera in the absence of any coryphal horn, and represents therefore the pentapodal form among the hornless Zygospyrida.

1. Pentaspyris pentacantha, n. sp. (Pl. 95, fig. 11).

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores irregular roundish, two pairs of larger pores on each side of the ring. Basal plate with four larger pores. All five feet cylindrical, S-shaped curved, strongly divergent, with few short branches, the two pectoral feet twice as long as the shell and the two tergal feet; odd caudal foot shorter.

Dimensions.—Shell 0.08 long, 0.13 broad; pectoral feet 0.2 long, tergal feet 0.1, caudal foot 0.06.

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

2. Pentaspyris isacantha, n. sp.

Shell subspherical, smooth, with slight sagittal stricture. Pores small, regular circular. Basal plate with six large pores (?). All five feet equal, cylindrical, C-shaped curved, slightly divergent, about as long as the shell.

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

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

Subfamily 6. Therospyrida, Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida tetrapoda with two pairs of descending basal feet, one pair corresponding to the anterior or pectoral, the other pair to the posterior or tergal feet of the Hexaspyrida.

Genus 459. Zygospyris,^[19] Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida with two pairs of lateral feet and an apical horn.

The genus Zygospyris and the following three genera represent together the peculiar subfamily of Therospyrida. These always possess four basal feet, like the Tetraspyrida; but whilst in the latter group two feet are sagittal, and two lateral, in the Therospyrida there are no sagittal feet at all, but the four feet are opposed in two lateral pairs; the anterior pair corresponds to the pectoral, the posterior to the tergal feet of the Hexaspyrida and Pentaspyrida; from these latter the Therospyrida have been derived by loss of the sagittal feet.

1. Zygospyris quadrupes, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores irregular roundish, on each side of the ring two pairs of larger pores. Apical horn conical, straight. Four feet equal, straight, divergent, conical, about as long as the shell and the horn.

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

Habitat.—South Atlantic, Station 335, depth 1425 fathoms.

2. Zygospyris equus, n. sp. (Pl. 83, fig. 16).

Shell subspherical, rough, with slight sagittal stricture. Pores small and numerous, subregular circular; no larger annular pores. Apical horn cylindrical, half as long as the shell. Two pectoral feet somewhat smaller than the two tergal feet, about as long as the shell, slightly divergent, cylindrical. The distal ends of the feet and of the horn form an ovate, dimpled and spinulate cone.

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

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

Genus 460. Elaphospyris,^[20] Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida with two pairs of lateral feet and three coryphal horns.

The genus Elaphospyris differs from the preceding Zygospyris, its ancestral form, in the possession of three coryphal horns (one odd apical and two paired frontal horns), and therefore bears to it the same relation that Triceraspyris does to Tripospyris among the Tripospyrida.

Subgenus 1. Giraffospyris, Haeckel, 1881, Prodromus, p. 442.

Definition.—Feet simple, not branched nor forked.

1. Elaphospyris heptaceros, Haeckel.

Ceratospyris heptaceros, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 2. Giraffospyris heptaceros, Haeckel, 1881, Prodromus, p. 442.

Shell nut-shaped, tuberculate, with slight sagittal stricture and subregular circular pores. Basal plate with four large pores. Apical horn small, conical, shorter than the two curved lateral horns, which are as long as the shell. Caudal and sternal feet small, conical, straight. Two pectoral feet slender, divergent, S-shaped, about as long as the shell.

Dimensions.—Shell 0.05 long, 0.07 broad; horns and feet 0.02 to 0.08 long.

Habitat.—Fossil in Barbados.

2. Elaphospyris capricornis, n. sp.

Shell nut-shaped, spiny, with slight sagittal stricture and numerous small circular pores. Basal plate with four large pores. Three horns slender, simple, about as long as the shell, the middle one straight, the two lateral curved. Four feet of nearly equal size, slender, curved, divergent, simple, twice as long as the shell and the horns.

Dimensions.—Shell 0.07 long, 0.09 broad; horns 0.08 long, feet 0.15 long.

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

Subgenus 2. Corythospyris, Haeckel, 1881, Prodromus, p. 443.

Definition.—Feet branched or forked.

3. Elaphospyris damaecornis, n. sp. (Pl. 84, fig. 10).

Shell flat and broad, nearly triangular, with slight sagittal stricture and irregular roundish pores; two very large pores on the frontal and on the occipital face, opposite on both edges of the broad sagittal ring. Basal plate with four large central and several smaller lateral pores. Three horns about half as long as the shell, with two to six irregular branches. Four feet of equal size, about as long as the shell, divergent, forked, with four to six irregular terminal branches. (The shell in fig. 10 is seen from the apical side.)

Dimensions.—Shell 0.09 long, 0.13 broad; horns 0.05 long, feet 0.1 long.

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

4. Elaphospyris cervicornis, n. sp. (Pl. 86, fig. 13).

Shell polyhedral, spiny, with deep sagittal stricture and a small number of large roundish pores; two pairs of large pores on each side of the ring. Basal plate with four pores. Three large horns as long as the shell arise from the apex between smaller conical spines; the middle odd horn simple, the two lateral each with a pair of branches. Two pectoral feet very large, divergent, with broad and irregular distal ramification, twice as long as the shell and as the two tergal feet, which are less branched. (Fig. 13 exhibits the shell from the dorsal side.)

Dimensions.—Shell 0.09 long, 0.11 broad; horns and smaller feet 0.07 to 0.09 long; pectoral feet 0.16 long.

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

5. Elaphospyris alcicornis, n. sp. (Pl. 86, fig. 12).

Shell nut-shaped, spiny, with sharp sagittal stricture and large roundish pentagonally framed pores; three pairs of larger pores on each side of the ring. Basal plate with four larger and four alternate smaller pores. There arise from the apex, between smaller spines, three large, divergent, pyramidal horns, which are nearly as long as the shell, and connected by an arched frontal bridge. Two pectoral feet very large, divergent, prismatic, longer than the shell, and at the distal end with a bunch of thick spines. Two tergal feet half as long and thick, simple (in the figure hidden behind the large pectoral feet).

Dimensions.—Shell 0.09 long, 0.11 broad; horns and smaller feet 0.06 long, pectoral feet 0.12 long.

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

Genus 461. Taurospyris,^[21] Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida with two pairs of lateral feet and one pair of lateral horns.

The genus Taurospyris bears only two frontal horns in the coryphal face of the shell, and may therefore be derived from the preceding closely allied Elaphospyris by reduction and loss of the middle or apical horn.

1. Taurospyris cervina, n. sp. (Pl. 95, fig. 12).

Shell nut-shaped, thorny, with deep sagittal stricture and irregular roundish pores; three pairs of larger pores on each side of the ring. Basal plate with four large pores. Two horns cylindrical, curved, widely divergent, about as long as the shell, branched. Four feet of nearly equal length, also cylindrical and curved, divergent, somewhat longer than the shell, in the distal half branched like a deer's antler.

Dimensions.—Shell 0.07 long, 0.11 broad; horns 0.03 long, feet 0.06 long.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms; also fossil in Barbados.

2. Taurospyris bovina, n. sp.

Shell subspherical, smooth, with slight sagittal stricture and small circular pores. Basal plate with six larger pores. Two horns conical, curved, divergent, about as long as the shell. Two pectoral feet very large, twice as long as the shell and as the two thinner tergal feet; all four feet curved, cylindrical, divergent, pointed at the distal end.

Dimensions.—Shell 0.08 long, 0.09 broad; horns and posterior feet 0.1, anterior feet 0.2 long.

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

Genus 462. Therospyris,^[22] Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida with two pairs of lateral feet, without apical horn.

The genus Therospyris has two pairs of lateral feet corresponding to those of the preceding three genera, but differs from them in the complete absence of horns on the coryphal face of the shell.

1. Therospyris canis, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores irregular, roundish. Basal plate with four longer pores. Surface covered with roundish tubercles. Four feet equal, divergent, about as long as the shell, thickened at the distal end, club-shaped, not forked.

Dimensions.—Shell 0.07 long, 0.11 broad; feet 0.09 long.

Habitat.—Fossil in Barbados.

2. Therospyris felis, n. sp. (Pl. 89, fig. 6).

Shell nut-shaped, mammillate, with sharp sagittal stricture. Pores large, irregularly roundish or polygonal, of somewhat different size. Basal plate with four large pores. Surface covered with hemispherical pointed mammillæ. Four feet equal, divergent, half as long as the shell, at the distal end forked, with few small branches.

Dimensions.—Shell 0.1 long, 0.15 broad; feet 0.05 long.

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

3. Therospyris leo, n. sp. (Pl. 89, fig. 5).

Shell nearly cubical, papillate, with slight sagittal stricture. Pores irregular, roundish; on each side of the ring three pairs of larger pores (the undermost the largest). Basal plate with two large pores. Surface covered with conical papillæ. Four feet equal, divergent, about as long as the shell, with an external spur in the middle, and irregularly branched spines at the distal end.

Dimensions.—Shell 0.08 long, 0.12 broad; feet 0.09 long.

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

Subfamily 7. Polyspyrida, Haeckel, 1881, Prodromus, p. 442.

Definition.—Zygospyrida polypoda, with numerous descending basal feet (at least seven to nine, usually twelve to sixteen or more).

Genus 463. Petalospyris,^[23] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Zygospyrida with numerous (seven to twelve or more) basal feet and one apical horn.

The genus Petalospyris and the following three genera form together the peculiar subfamily of Polyspyrida, differing from the other Zygospyrida in the multiplication of the radial feet, which descend from the basal face of the shell; they may therefore be also called "Zygospyrida multiradiata," and bear the closest relationship to the Archiphænida (or the "Monocyrtida multiradiata"). They differ, however, from the latter in the presence of the distinct sagittal stricture, characteristic of all Spyroidea. The number of the basal feet, which form a coronet around the margin of the basal plate, is commonly between twelve and sixteen, but often more. Their form is usually flat, lamellar, but often also more or less cylindrical or conical.

Subgenus 1. Petalospyrantha, Haeckel.

Definition.—Basal plate with two large collar pores only, separated by the base of the primary ring.

1. Petalospyris foveolata, Ehrenberg.

Petalospyris foveolata, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 14; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 80, Taf. xxii. fig. 10.

Shell campanulate, smooth, with distinct sagittal stricture and subregular circular pores. Basal plate with two large collar pores only. Apical horn and the eight feet slender, conical, slightly curved, about as long as the shell; feet somewhat divergent (often seven or nine instead of eight).

Dimensions.—Shell diameter 0.04 to 0.05; length of the horn and the feet 0.04 to 0.05.

Habitat.—Fossil in Barbados.

2. Petalospyris floscula, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture and subregular circular pores. Basal plate with two large triangular pores only. Apical horn slender, conical, twice as long as the shell. Twelve to sixteen feet flattened, leaf-shaped, broad, slightly divergent, as long as the shell, with truncate distal end.

Dimensions.—Shell 0.06 long, 0.09 broad; horn 0.12 long, feet 0.05 to 0.07 long.

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

Subgenus 2. Petalospyrella, Haeckel.

Definition.—Basal plate with three large collar pores (two paired posterior cardinal, and an odd anterior sternal pore).

3. Petalospyris triomma, n. sp. (Pl. 87, fig. 14).

Shell nut-shaped, tuberculate, with sharp sagittal stricture and irregular roundish pores. Basal plate with three large pores and three alternate smaller. Apical horn stout, conical, half as long as the shell. Twelve to fifteen feet, divergent, curved, pointed, as long as the horn.

Dimensions.—Shell 0.06 long, 0.08 broad; horn and feet 0.03 long.

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

4. Petalospyris platyacantha, Ehrenberg.

Petalospyris platyacantha, Ehrenberg, Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 80, Taf. xxii. fig. 8.

Shell campanulate, smooth, with slight sagittal stricture and small irregular roundish pores. Basal plate with three large pores (?). Apical horn very strong, three-sided pyramidal, twice as long as the shell (its edge is described by Ehrenberg as a "canaliculus.") Feet ten to twelve, flat, triangular, vertical, about as long as the shell.

Dimensions.—Shell 0.04 long, 0.05 broad; 0.07 long, feet 0.03 long.

Habitat.—Fossil in Barbados.

5. Petalospyris corona, Stöhr.

Petalospyris corona, Stöhr, 1880, Palæontogr., vol. xxvi. p. 98, Taf. iii. fig. 13.

Shell nut-shaped, smooth, with slight sagittal stricture and very numerous small circular pores; on each side of the stricture three larger annular pores (the undermost the largest). Basal plate with three large pores only. Apical horn very small, conical. Feet twelve to eighteen, short conical, nearly vertical, shorter than the half shell (in my specimen from Caltanisetta much stouter than in that of Stöhr).

Dimensions.—Shell 0.07 long, 0.09 broad; horn and feet 0.01 to 0.03 long.

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

Subgenus 3. Petalospyrissa, Haeckel.

Definition.—Basal plate with four collar pores (two larger posterior cardinal and two smaller anterior jugular pores).

6. Petalospyris octopus, n. sp. (Pl. 87, fig. 11).

Shell nut-shaped, tuberculate, with sharp sagittal stricture and irregular, roundish pores. Basal plate with four larger pores. Horn slender, conical, half as long as the shell. Feet eight, very slender, about three times as long as the shell, subvertical, with outer convex edge and convergent ends.

Dimensions.—Shell 0.06 long, 0.09 broad; horn 0.03 long, feet 0.2 long.

Habitat.—Tropical Atlantic, Station 342, depth 1445 fathoms.

7. Petalospyris eupetala, Ehrenberg.

Petalospyris eupetala, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xxii. fig. 4.

Shell nut-shaped, tuberculate, with slight sagittal stricture and scattered small circular pores. Basal plate with four large collar pores (sometimes surrounded by several small peripheral pores). Apical horn slender, conical, as long as the shell. Feet sixteen to twenty, laminated and truncate, of the same length, nearly vertical and parallel.

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

Habitat.—Fossil in Barbados.

8. Petalospyris anthemis, n. sp.

Shell nut-shaped, spinulate, with deep sagittal stricture and irregular, roundish pores. Basal plate with four large pores of equal size. Apical horn conical, twice as long as the shell. Feet twenty to thirty, laminated and truncate, as long as the shell, divergent.

Dimensions.—Shell 0.05 long, 0.08 broad; horn 0.1 long, feet 0.6 long.

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

9. Petalospyris tessaromma, n. sp.

Shell subspherical, with slight sagittal stricture and few small pores; on each side of the stricture four larger, square, annular pores. Basal plate with four large collar pores (two larger cardinal and two smaller jugular pores). Horn and feet conical, about half as long as the shell. Feet twenty to twenty-five, slightly curved, convergent.

Dimensions.—Shell diameter 0.08; horn and feet 0.04.

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

Subgenus 4. Petalospyromma, Haeckel.

Definition.—Basal plate with numerous (six or more) collar pores, commonly three or four larger central, and six to twelve smaller peripheral pores.

10. Petalospyris novena, n. sp. (Pl. 83, fig. 12).

Shell nut-shaped, tuberculate, with slight sagittal stricture and irregular, roundish pores. Basal plate with nine pores (three large primary and three alternate pairs of small secondary pores). Nine long corresponding feet, twice to four times as long as the shell (three very thick primary, and three alternate pairs of thin secondary feet). All feet cylindrical, curved, widely divergent. Horn conical.

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

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

11. Petalospyris argiscus, Ehrenberg.

Petalospyris argiscus, Ehrenberg, 1875, Abhandl. d. k. Akad. Wiss. Berlin, p. 80, Taf. xxii. figs. 1, 2. Petalospyris argiscus, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 539, Taf. xxxii. fig. 17, a, b.

Shell nut-shaped, tuberculate, with slight sagittal stricture and irregular, roundish pores. Basal plate with nine pores (three larger central and three alternate pairs of smaller peripheral pores). Apical horn slender, spindle-shaped, about as long as the shell. Twenty to twenty-five feet, of the same length, broad, lamellar and truncate, nearly vertical, slightly divergent.

Dimensions.—Shell 0.06 long, 0.1 broad; horn and feet 0.05 to 0.07 long.

Habitat.—Fossil in Barbados.

12. Petalospyris papillata, n. sp.

Shell nearly cubical, papillate, without external sagittal stricture, with small, irregular, roundish pores. Basal plate with six pores (three larger and three alternate smaller). Apical horn conical, half as long as the shell. Feet twenty to thirty, one-half to one-third as long, conical, divergent.

Dimensions.—Shell diameter 0.09; horn 0.04 long, feet 0.03 to 0.05 long.

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

13. Petalospyris dictyocubus, n. sp. (Pl. 86, fig. 6).

Shell nearly cubical, smooth, without external stricture, but with a complete, parietal, square, sagittal ring. On each side of the ring four pairs of larger pores, whilst the lateral pores are smaller and more numerous. Basal plate also with four pairs of larger pores and smaller lateral pores. Apical horn and basal feet short, pyramidal, scarcely one-fourth as long as the shell. The three primary feet are larger than the six to nine secondary feet.

Dimensions.—Shell diameter 0.08; horn and feet 0.02 long.

Habitat.—Central Pacific, Station 274, surface.

14. Petalospyris bellidiastrum, n. sp.

Shell nut-shaped, tuberculate, with slight sagittal stricture and irregular, roundish pores. Basal plate with twelve pores (four central larger and eight peripheral smaller pores). Apical horn slender, conical, about as long as the shell (sometimes ramified at the distal end). Feet sixteen to twenty, broadly lamellar, truncate, divergent, about as long as the shell.

Dimensions.—Shell 0.08 long, 0.1 broad; horn and feet 0.07 to 0.09 long.

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

15. Petalospyris dinoceras, n. sp. (Pl. 87, fig. 12).

Shell nut-shaped, mammillate, without external stricture, but with complete external sagittal ring. Pores subregular, circular. Basal plate with four large central pores, surrounded by a circle of twelve to twenty small peripheral pores. Apical horn very large, spindle-shaped, one and a half times as long as the shell. Feet twenty-five to thirty, broadly lamellar, truncate, divergent, about as long as the shell.

Dimensions.—Shell 0.11 long, 0.13 broad; horn 0.15 long, feet 0.09 long.

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

16. Petalospyris furcata, n. sp.

Shell nut-shaped, smooth, with sharp sagittal stricture. Pores numerous, small, and circular; no larger annular pores. Basal plate with four larger and four alternate pairs of smaller pores. Horn conical, about as long as the shell. Feet fifteen to twenty, broadly lamellar, about twice as long as the shell, in the distal half forked.

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

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

17. Petalospyris lobata, n. sp. (Pl. 87, fig. 13).

Shell subspherical, smooth, with slight sagittal stricture. Pores small, roundish; on each side of the ring two pairs of larger annular pores. Basal plate with four pores. Horn stout, three-sided prismatic, half as long as the shell. Feet twelve to sixteen, lamellar, lobate (the most part with three lobes), nearly vertical, about as long as the shell.

Dimensions.—Shell diameter 0.05; horn 0.03, feet 0.05 long.

Habitat.—South Atlantic, Station 335, depth 1425 fathoms.

Genus 464. Anthospyris,^[24] Haeckel, 1881, Prodromus, p. 443.

Definition.—Zygospyrida with numerous (seven to nine or more) basal feet and three coryphal horns.

The genus Anthospyris differs from the preceding Petalospyris, its ancestral form, in the possession of three horns on the coryphal face (one odd middle apical horn and two paired frontal horns, one on each side). The former therefore bears to the latter the same relation that Triceraspyris does to Tripospyris and Liriospyris to Hexaspyris.

1. Anthospyris mammillata, n. sp. (Pl. 87, fig. 16).

Shell nut-shaped, mammillate, with deep sagittal stricture and irregular, polygonal pores. Basal plate with two large ovate pores (?). The pediculate apical horn and the two frontal horns stout and short, conical, twice to three times as large as the conical papillæ of the surface. Feet twelve to fifteen, lanceolate lamellar, pointed, divergent, about as long as the shell.

Dimensions.—Shell 0.05 long, 0.08 broad; horns 0.03, feet 0.04 long.

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

2. Anthospyris spathulata, n. sp. (Pl. 87, fig. 15).

Shell subspherical, thorny, with slight sagittal stricture and irregular, roundish pores. Basal plate with three large pores. The three horns spindle-shaped, half as long as the ten to twelve thin feet, which are pediculate, shovel-shaped, a little divergent, and shorter than the shell.

Dimensions.—Shell 0.05 diameter; horn 0.02 long, feet 0.04 long.

Habitat.—North Pacific, Station 250, depth 3050 fathoms.

3. Anthospyris diaboliscus, Haeckel.

Petalospyris diaboliscus, Ehrenberg, 1854, Mikrogeol., Taf. xxxvi. fig. 12; Abhandl. d. k. Akad. d. Wiss. Berlin, 1875, p. 80, Taf. xxii. fig. 3.

Shell nut-shaped, smooth, with slight sagittal stricture and small circular pores. Basal plate with four large pores. Apical horn straight conical, frontal horns curved laterally. Feet nine to twelve, of about the same length as the horns and the shell, broad lamelliform, truncate, nearly vertical, slightly curved.

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

Habitat.—Fossil in Barbados.

4. Anthospyris arachnoides, Haeckel.

Petalospyris arachnoides, Haeckel, 1862, Monogr. d. Radiol., p. 294, Taf. xii. fig. 7.

Shell nut-shaped, tuberculate, with slight sagittal stricture and irregular, polygonal pores. Basal plate with four large pores (?). Apical horn straight, conical, longer than the two curved lateral horns. Feet ten, slender, S-shaped, widely divergent, about as long as the shell is broad.

Dimensions.—Shell 0.05 long, 0.08 broad; horns 0.03 to 0.05 long, feet 0.08 long.

Habitat.—Mediterranean (Messina), Atlantic, Station 354, surface.

5. Anthospyris aculeata, n. sp. (Pl. 86, fig. 5).

Shell campanulate, spiny, with deep sagittal stricture and irregular, roundish pores. On each side of the stricture three pairs of larger annular pores. Basal plate with two large square pores. The three horns of the same size as, and similar form to, the ten to fifteen feet, slender pyramidal, straight, divergent, about half as long as the shell. (This species is very variable and closely allied to Ceratospyris.)

Dimensions.—Shell diameter 0.08 to 0.12; horns and feet 0.04 to 0.06 long.

Habitat.—Central Pacific, Stations 266 to 274, surface.

6. Anthospyris doronicum, n. sp. (Pl. 87, fig. 18).

Shell nut-shaped, spiny, with a deep sagittal stricture and small circular pores. On each side of the stricture two pairs of very large square annular pores. Basal plate with four larger collar pores and a corona of numerous small peripheral pores. Three horns spindle-shaped, divergent, about half as long as the shell. Feet twenty-five to thirty, broad, lamellar, lanceolate, pointed, divergent, nearly as long as the shell.

Dimensions.—Shell 0.1 long, 0.13 broad; horns 0.06, feet 0.09 long.

Habitat.—South Pacific, Station 296, depth 1825 fathoms.

7. Anthospyris tragopogon, n. sp. (Pl. 87, fig. 17).

Shell nut-shaped, tuberculate, with distinct sagittal stricture and small regular circular pores. Basal plate with numerous small pores. Apical horn very large, spindle-shaped, twice as long as the shell; frontal horns small, scarcely one-fourth as long, curved laterally. Feet twenty-five to thirty, three to four times as long as the shell, lamellar, lanceolate, pointed, parallel, vertical.

Dimensions.—Shell 0.08 long, 0.11 broad; apical horn 0.16, feet 0.2 long.

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

Genus 465. Ceratospyris,^[25] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Zygospyrida with numerous (seven to twelve or more) basal feet and numerous coryphal horns.

The genus Ceratospyris differs from all the other Zygospyrida in the possession of numerous large spines on the surface of the shell, which usually exhibits only a small number of large pores or meshes. The lower spines which cover the inferior or basal face of the shell (usually nine to twelve or more) may be compared to the descending "basal feet" of the other Zygospyrida; the upper spines, however, which cover the superior or coryphal face (usually six to nine, rarely more), may be regarded as "coryphal horns." In many species of this genus the lattice-work of the shell is of a peculiar loose kind, with few large meshes, resembling the wicker-work of the Plectanida.

Subgenus 1. Lophospyris, Haeckel, 1881, Prodromus, p. 443.

Definition.—Spines simple, not branched. Meshes of the shell usually polygonal, or roundish with polygonal frames. Bars of the network prismatic.

1. Ceratospyris polygona, n. sp. (Pl. 86, fig. 1).

Shell polyhedral, with deep sagittal stricture, studded with twenty-four to thirty long simple straight slender pyramidal spines, which are as long as the shell or longer. All pores large, polygonal. On the frontal and the occipital face two pairs of very large pores only, the superior pentagonal, larger than the inferior tetragonal. Basal plate with two triangular pores. Bars of the loose framework three-sided prismatic, thin.

Dimensions.—Shell 0.08 long, 0.12 broad; spines 0.06 to 0.12 long.

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

2. Ceratospyris pentagona, Ehrenberg.

Ceratospyris pentagona, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 287, Taf. x. fig. 15.

Shell polyhedral, with slight sagittal stricture, studded with twenty-four to thirty small simple conical spines, which are shorter than one-fourth of the shell. Most pores pentagonal. On the frontal and the occipital face two pairs of large pores only, the superior smaller than the inferior. Basal plate with four quadrangular pores. Bars of the network prismatic, thin.

Dimensions.—Shell 0.07 long, 0.11 broad; spines 0.01 to 0.02 long.

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

3. Ceratospyris allmersii, n. sp. (Pl. 86, fig. 3).

Shell polyhedral, with slight sagittal stricture, studded with thirty to forty prismatic spines which are not longer than half the shell. Most pores pentagonal. On the frontal face two, on the occipital three pairs of larger pores; the inferior the largest. Basal plate with two rhomboidal pores (?). Bars of the network three-sided prismatic, thin. Dedicated to my dear friend, the excellent poet and naturalist, Hermann Allmers, of Rechtenfleth.

Dimensions.—Shell 0.08 long, 0.12 broad; spines 0.01 to 0.03.

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

4. Ceratospyris mulderi, n. sp. (Pl. 86, fig. 4).

Shell polyhedral, with deep sagittal stricture, studded with fifty to seventy prismatic spines; two inferior (pectoral) spines about as long as the shell, the others much shorter. Pores polygonal. On the frontal and the occipital face one pair of very large pores. Basal plate with two distinctly hexagonal pores. Bars of the loose network prismatic. Dedicated to my dear friend, the excellent author and painter, Ludwig Mulder, of the Hague.

Dimensions.—Shell 0.07 long, 0.12 broad; spines 0.01 to 0.08.

Habitat.—Indian Ocean, Sunda Straits (Rabbe), surface.

5. Ceratospyris strasburgeri, n. sp. (Pl. 86, fig. 2).

Shell polyhedral, with slight sagittal stricture, studded with thirty to forty prismatic spines, which are about half as long as the shell (two or four inferior are longer). Pores roundish, with polygonal frames. On the frontal and occipital face two pairs of larger pores (the superior smaller). Basal plate with two large pentagonal pores. Bars of the network prismatic. Dedicated to my dear friend, the celebrated botanist, Professor Eduard Strasburger, of Bonn.

Dimensions.—Shell 0.07 long, 0.1 broad; spines 0.02 to 0.04.

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

6. Ceratospyris mülleri, Stöhr.

Ceratospyris mülleri, Stöhr, 1880, Palæontogr., vol. xxvi. Taf. iii. fig. 15.

Shell polyhedral, with slight collar stricture, studded with forty to fifty pyramidal spines, shorter than half the shell. Pores circular, with pentagonal frames of the same breadth, all nearly of equal size. (Basal plate with four pores?) Bars of the network prismatic. Dedicated to Johannes Müller.

Dimensions.—Shell 0.08 long, 0.1 broad; spines 0.01 to 0.03.

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

7. Ceratospyris krausei, n. sp. (Pl. 86, fig. 10).

Shell nut-shaped, with deep sagittal stricture, studded with forty to fifty strong conical spines; six basal spines as long as the shell and two to three times as long as the others. Pores roundish polygonal, twice to three times as broad as the bars; two pairs of larger pores on each side of the ring. (Basal plate with four large pores?) Bars of the network rounded, thick. Dedicated to my dear friend, the excellent author, Ernst Krause (Carus Sterne), of Berlin.

Dimensions.—Shell 0.06 long, 0.09 broad; spines 0.03 to 0.08.

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

8. Ceratospyris preyeri, n. sp. (Pl. 86, fig. 9).

Shell nut-shaped, with slight sagittal stricture, studded with ten to twelve longer club-shaped spines (about as long as the shell) and numerous smaller conical spines. Pores irregular, roundish, numerous; two pairs of larger pores on each side of the ring. Basal plate with four large pores. Bars of the network rounded. Dedicated to my honoured friend and colleague, the celebrated investigator of psychical ontogeny, Professor William Preyer, of Jena.

Dimensions.—Shell 0.07 long, 0.09 broad; spines 0.02 to 0.08 long.

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

9. Ceratospyris echinus, Ehrenberg.

Ceratospyris echinus, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx, fig. 12.

Shell subspherical, with slight sagittal stricture, studded with numerous conical curved spines; six basal and one apical spine are larger than the others, about as long as the shell. Pores numerous, small, circular. Basal plate with numerous pores. Bars of the network roundish.

Dimensions.—Shell 0.05 long, 0.06 broad; spines 0.02 to 0.05 long.

Habitat.—Fossil in Barbados.

Subgenus 2. Cladospyris, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Spines forked or branched. Meshes roundish or polygonal.

10. Ceratospyris ramosa, Ehrenberg.

Ceratospyris ramosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 66, Taf. xx. fig. 7. Cladospyris ramosa, Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Shell nut-shaped, with slight sagittal stricture, studded with numerous conical, irregularly branched spines. The largest about as long as the shell. Pores irregular, roundish; on each side of the ring two pairs of larger pores. Basal plate with four pores. Bars of the network roundish.

Dimensions.—Shell 0.06 long, 0.08 broad; spines 0.02 to 0.08 long.

Habitat.—Fossil in Barbados.

11. Ceratospyris carnerii, n. sp. (Pl. 86, fig. 11).

Shell nut-shaped, with sharp sagittal stricture, studded with numerous pyramidal spines; two basal spines are larger, as long as the shell, and irregularly branched. Pores polygonal; on each side of the ring three pairs of larger pores. Basal plate with four large pores. Dedicated to my dear friend, the excellent monistic philosopher, B. von Carneri.

Dimensions.—Shell 0.09 long, 0.12 broad; spines 0.02 to 0.08 long.

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

12. Ceratospyris calorrhiza, n. sp. (Pl. 87, fig. 19).

Shell nut-shaped, with deep sagittal stricture, studded with numerous conical strong spines, about one-fourth as long as the shell. Basal spines irregularly branched, with root-like ends. Pores irregular, roundish, some larger pores on each side of the ring. Basal plate with four larger pores. Bars of the network roundish.

Dimensions.—Shell 0.1 long, 0.14 broad; spines 0.02 to 0.04 long.

Habitat.—Central Pacific, Station 271, surface.

Genus 466. Gorgospyris,^[26] Haeckel, 1881, Prodromus, p. 443.

Definition.—Zygospyrida with numerous (seven to twelve or more) basal feet, without coryphal horns.

The genus Gorgospyris agrees with the three preceding genera in the possession of numerous basal feet, but differs from them in the complete absence of any horns on the coryphal face. It represents therefore the "hornless polypedal Zygospyrida," and may be derived from Petalospyris by loss of the original apical horn. The feet are commonly numerous, and often form a circle around the margin of the basal plate, similar to the circle of tentacles in many Medusæ (Gorgon).

Subgenus 1. Gorgospyrium, Haeckel.

Definition.—Feet simple, not branched.

1. Gorgospyris medusa, n. sp. (Pl. 87, fig. 1).

Shell hemispherical, papillate, with slight sagittal stricture and subregular circular pores. Basal plate with three large collar pores (by mistake not correctly represented in the figure). Ten to twelve slender feet, twice as long as the shell, strongly curved and divergent, of equal length.

Dimensions.—Shell 0.06 long, 0.08 broad; feet 0.1 long.

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

2. Gorgospyris medusetta, n. sp. (Pl. 87, fig. 2).

Shell misshaped, smooth, with deep sagittal stricture and irregular, roundish pores. Basal plate with three large collar pores, alternating with three pairs of smaller pores. Sixteen to twenty slender feet, about as long as the shell, slightly curved and divergent, of nearly equal length.

Dimensions.—Shell 0.05 long, 0.08 broad; feet 0.05 long.

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

3. Gorgospyris ehrenbergii, Haeckel.

Petalospyris pentas, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xxii. fig. 11.

Shell nut-shaped, smooth, with slight sagittal stricture and unequal circular pores. Basal plate with three large central pores, alternating with three pairs of smaller pores, and with a peripheral circle of smaller pores. Twenty-four to thirty short truncated feet, shorter than half the shell.

Dimensions.—Shell 0.05 long, 0.07 broad; feet 0.02 long.

Habitat.—Fossil in Barbados.

4. Gorgospyris polypus, n. sp. (Pl. 87, fig. 3).

Shell hemispherical, papillate, with slight sagittal stricture and subregular circular pores. Basal plate with four larger and four alternating smaller pores. Feet sixteen to twenty, slender, carved, divergent; four primary feet larger, twice to three times as long as the shell and the other feet.

Dimensions.—Shell 0.08 long, 0.1 broad; feet 0.1 to 0.2 long.

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

5. Gorgospyris eurycolpos, n. sp. (Pl. 87, fig. 5).

Shell nut-shaped, rough, with deep sagittal stricture and irregular, roundish pores; two to three pairs of larger annular pores on each side of the stricture. Basal plate with four large collar pores. Feet eight, short, triangular, vertical, about one-fourth as long as the shell.

Dimensions.—Shell 0.08 long, 0.13 broad; feet 0.02 long.

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

6. Gorgospyris liriope, n. sp. (Pl. 87, fig. 6).

Shell nut-shaped, thorny, with sharp sagittal stricture and irregular, roundish pores. Two pairs of larger annular pores on each side of the ring. Basal plate with two very large circular pores only. Eight to ten short feet vertical, about one-fourth as long as the shell, with an elegant papillate knob at the distal end.

Dimensions.—Shell 0.07 long, 0.1 broad; feet 0.02 long.

Habitat.—South Atlantic, Station 323, depth 1900 fathoms.

7. Gorgospyris lamellosa, n. sp.

Shell nut-shaped, tuberculate, with subregular circular pores. Basal plate with four larger and four alternate pairs of smaller pores. Feet fifteen to twenty-five, broad, lamellar, vertical, truncate, about as long as the shell, of irregular size and form, very variable.

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

Habitat.—Fossil in Barbados.

Subgenus 2. Thamnospyris, Haeckel, 1881, Prodromus, p. 443.

Definition.—Feet divided or branched.

8. Gorgospyris schizopodia, n. sp. (Pl. 87, fig. 4).

Shell hemispherical, smooth, with slight sagittal stricture and small regular, circular pores. Basal plate with four large central and a circle of small pores. Feet fifteen to twenty, broad, lamellar, confluent at the base, about as long as the shell, irregularly divided or forked.

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

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

9. Gorgospyris thamnopodia, n. sp.

Thamnospyris thamnopodia, Haeckel, 1881, Prodromus, p. 143.

Shell nut-shaped, tuberculate, with deep sagittal stricture and irregular, roundish pores. Basal plate with numerous small pores. Feet twenty to thirty, slender, curved, divergent, twice to three times as long as the shell, irregularly branched.

Dimensions.—Shell 0.08 long, 0.12 broad; feet 0.15 to 0.25 long.

Habitat.—Indian Ocean (Madagascar), Rabbe, surface.

Subfamily 8. Circospyrida, Haeckel, 1881, Prodromus, p. 443.

Definition.—Zygospyrida apoda, without descending basal feet.

Genus 467. Circospyris,^[27] Haeckel, 1881, Prodromus, p. 444.

Definition.—Zygospyrida without basal feet, with an apical horn.

The genus Circospyris and the following closely allied genus Dictyospyris represent together the small subfamily Circospyrida, differing from all other Zygospyrida in the absence of feet on the basal face. They have probably arisen from the Tripospyrida (Tripospyris) by reduction and loss of the feet (in the same way as the eradiate Cyrtoidea from the triradiate). But it is also possible that many of the Circospyrida (if not all) are derived directly from the Semantida (Clathrocircus) by the closing of the two lateral openings and by completing the framework.

1. Circospyris nucula, n. sp. (Pl. 95, fig. 13).

Shell nut-shaped, compressed, smooth, with prominent sagittal ring. On each side of the ring three to four pairs of very large annular polygonal pores. Lateral pores small and numerous, roundish. Basal plate with two large pores only. Horn slender, conical, shorter than half the shell.

Dimensions.—Shell 0.11 long, 0.13 broad.

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

2. Circospyris gigas, Haeckel.

Dictyospyris gigas, Ehrenberg, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xix. fig. 6.

Shell nut-shaped, tuberculate, with distinct sagittal stricture. On each side of the ring four pairs of larger annular pores. Lateral pores roundish, smaller. Basal plate with four large central and a circle of eight to twelve smaller peripheral pores. Horn cylindrical, about half as long as the shell (in the inverted figure of Ehrenberg directed downwards).

Dimensions.—Shell 0.1 to 0.15 long, 0.15 to 0.2 broad; horn 0.05 to 0.08 long.

Habitat.—Fossil in Barbados.

3. Circospyris tridentata, Haeckel.

Dictyospyris tridentata, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xix. fig. 10, a, b.

Shell nut-shaped, smooth, with sharp sagittal stricture. On each side of the ring two pairs of large annular pores. Lateral pores roundish, smaller. Basal plate with six large pores. Horn slender, cylindrical, about as long as the shell, with three sharp teeth at the distal end.

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

Habitat.—Fossil in Barbados.

Genus 468. Dictyospyris,^[28] Ehrenberg, 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54.

Definition.—Zygospyrida without basal feet, and without coryphal horns.

The genus Dictyospyris, the last and simplest of the twenty-eight genera of Zygocyrtida, may be regarded either as a primordial ancestral form of this large family, or more probably as the last and most reduced form of it. In the former case the total absence of coryphal horns and basal feet is primary, in the latter case secondary, effected by phylogenetic reduction and loss. But it is also possible that in one part of the numerous species of this genus the former case, and in another the latter takes place, and that one part of Dictyospyris may be directly developed from the Semantida or Coronida (the lattice shell becoming complete), another part arising from the Tripospyrida or Dipospyrida (the horns and feet becoming lost).

Subgenus 1. Dictyospyrantha, Haeckel.

Definition.—Basal plate with two large pores only (the primary jugular pores of Semantis).

1. Dictyospyris distoma, n. sp. (Pl. 89, figs. 11, 12).

Shell nut-shaped, smooth, or somewhat tuberculate, with deep sagittal stricture. Pores not numerous, large, roundish-polygonal; three pairs of large annular pores on each side of the ring. Basal plate with two very large pentagonal roundish collar pores.

Dimensions.—Shell 0.06 long, 0.08 broad.

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

2. Dictyospyris stalactites, n. sp. (Pl. 89, fig. 7).

Shell nut-shaped, covered with irregular ramified tubercles (like stalactites), with deep sagittal stricture. Pores not numerous, large, irregular, roundish. Two pairs of large triangular pores on each side of the ring (the inferior larger). Basal plate with two very large semicircular collar pores.

Dimensions.—Shell 0.07 long, 0.09 broad.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms; also fossil in Barbados.

3. Dictyospyris biloba, n. sp.

Shell subspherical, tuberculate, with slight sagittal stricture. Pores very numerous, small, circular. No larger pores on either side of the ring. Basal plate with two very large circular pores, surrounded by a circle of smaller pores.

Dimensions.—Shell 0.07 long, 0.08 broad.

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

Subgenus 2. Dictyospyrella, Haeckel.

Definition.—Basal plate with three large collar pores (two paired posterior cardinal pores and an odd anterior sternal pore).

4. Dictyospyris triomma, n. sp.

Shell nut-shaped, smooth, with deep sagittal stricture. Pores not numerous, large, polygonal roundish, two pairs of very large annular pores on each side of the ring. Basal plate with three large triangular pores. No free internal procolumella.

Dimensions.—Shell 0.06 long, 0.09 broad.

Habitat.—Indian Ocean, Zanzibar (Pullen), depth 2200 fathoms.

5. Dictyospyris tristoma, Ehrenberg.

Dictyospyris tristoma, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xix. fig. 9.

Shell nut-shaped, tuberculate, with slight sagittal stricture. Pores numerous, irregular, roundish. Three pairs of larger annular pores on each side of the ring. Basal plate with three large semi-circular pores (the sternal odd pore apparently halved by an internal free procolumella).

Dimensions.—Shell 0.05 long, 0.08 broad.

Habitat.—Fossil in Barbados and Sicily (Caltanisetta).

6. Dictyospyris triloba, Ehrenberg.

Dictyospyris triloba, Ehrenberg, 1876, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xix. fig. 8.

Shell nut-shaped, spinulate, without external stricture, but with a complete internal sagittal ring. Pores numerous, subregular circular; no larger annular pores. Basal plate with three large, heart-shaped two-lobed collar pores.

Dimensions.—Shell 0.05 long, 0.07 broad.

Habitat.—Fossil in Barbados.

7. Dictyospyris gigas, Bütschli.

Dictyospyris gigas, Bütschli, 1880, Zeitschr. f. wiss. Zool., vol. xxxvi., p. 539, Taf. xxxii. fig. 14a, 14b.

Shell subspherical, smooth, with a half (ventral) sagittal stricture, and a nearly complete internal ring. Pores very numerous and small, circular. No larger annular pores. Basal plate with three large collar pores (the sternal odd pore apparently divided into two jugular pores by the visible free procolumella.) (Compare Circospyris gigas, p. 1072 = Dictyospyris gigas, Ehrenberg).

Dimensions.—Shell 0.1 long, 0.14 broad.

Habitat.—Fossil in Barbados.

Subgenus 3. Dictyospyrissa, Haeckel.

Definition.—Basal plate with four large collar pores (two larger posterior cardinal and two smaller anterior jugular pores).

8. Dictyospyris fenestra, Ehrenberg.

Dictyospyris fenestra, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xix. fig. 11.

Shell nearly cubical, smooth, without external sagittal stricture. Internal sagittal ring complete. Pores small, roundish; on each side of the ring two crossed pairs of large, square, equal, annular pores. Basal plate also with four longer pores of nearly equal size.

Dimensions.—Shell 0.05 long, 0.07 broad.

Habitat.—Fossil in Barbados.

9. Dictyospyris tetrastoma, Ehrenberg.

Dictyospyris tetrastoma, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xix. fig. 12.

Shell nut-shaped, tuberculate, with slight sagittal stricture. Pores numerous, irregular, roundish. No larger annular pores. Basal plate with four large ovate collar pores (the two cardinal twice as large as the two jugular pores).

Dimensions.—Shell 0.05 long, 0.07 broad.

Habitat.—Cosmopolitan; Atlantic, Indian, Pacific; also fossil in Barbados and Sicily.

10. Dictyospyris spinulosa, Ehrenberg.

Dictyospyris spinulosa, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 70, Taf. xix. fig. 13. ? Ceratospyris borealis, Bailey, 1856, Amer. Journ. of Science and Arts, vol. xxii. pl. i. fig. 3.

Shell nut-shaped, spinulate, without external stricture, with an internal free sagittal ring. Pores numerous, irregular, roundish; on each side of the ring two pairs of very large square pores. Basal plate with four large collar pores.

Dimensions.—Shell 0.07 long, 0.08 broad.

Habitat.—Central Pacific, Stations 271 to 274, depth 2350 to 2750 fathoms; also fossil in Barbados.

11. Dictyospyris mammillaris, n. sp. (Pl. 89, figs. 9, 10).

Shell mammillate, nut-shaped, with deep sagittal stricture. Mammillæ of the surface hemispherical, with a conical apex. Pores not numerous, large, roundish. Two pairs of large pores on each side of the ring. Basal plate with four large pores.

Dimensions.—Shell 0.06 long, 0.08 broad.

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

12. Dictyospyris anthophora, n. sp. (Pl. 89, fig. 8).

Shell tuberculate, nut-shaped, nearly cubical, without external sagittal strictures. Pores not numerous, large, polygonally roundish. Bars between them compressed, elevated, with large, campanulate or flower-like tubercles on the nodal points. Basal plate with four large pores.

Dimensions.—Shell 0.07 long, 0.09 broad.

Habitat.—North Atlantic, Station 349, depth 2450 fathoms.

13. Dictyospyris quadriloba, n. sp.

Shell nut-shaped, smooth, with deep sagittal stricture. Pores numerous, small, circular, on each side of the ring three to four times as large as on the lateral sides. Basal plate with four very large collar pores and a circle of twenty to twenty-five very small peripheral pores.

Dimensions.—Shell 0.08 long, 0.11 broad.

Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.

14. Dictyospyris messanensis, J. Müller.

Dictyospyris messanensis, J. Müller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 46, Taf. ii. fig. 8. Dictyospyris messanensis, Haeckel, 1862, Monogr. d. Radiol., p. 291.

Shell nut-shaped, spinulate, with deep sagittal stricture. Pores numerous and small, irregular roundish. No larger annular pores on the sides of the ring. Basal plate with four large, nearly equal, pear-shaped collar pores.

Dimensions.—Shell 0.06 long, 0.08 broad.

Habitat.—Mediterranean; Messina, surface.

Subgenus 4. Dictyospyromma, Haeckel.

Definition.—Basal plate with six or more collar pores.

15. Dictyospyris hexastoma, n. sp.

Shell nut-shaped, tuberculate, with deep sagittal stricture. Pores small, irregular, roundish. Three pairs of larger pores on each side of the ring. Basal plate with six large pores; the middle pair (cardinal) twice as large as the anterior (jugular) and the posterior (cervical).

Dimensions.—Shell 0.08 long, 0.12 broad.

Habitat.—Fossil in Barbados.

16. Dictyospyris enneastoma, n. sp.

Shell ellipsoidal, smooth, without external sagittal stricture, but with an internal free sagittal ring. Pores small and numerous, regular, circular. No larger annular pores. Basal plate with nine pores, three larger interradial alternating with three pairs of adradial.

Dimensions.—Shell 0.07 long, 0.11 broad.

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

17. Dictyospyris polystoma, n. sp.

Shell nut-shaped, mammillate, with distinct sagittal stricture. Pores small and numerous, irregular, on each side of the ring three to five times as large as on the lateral sides. Basal plate with twelve large pores (four central and four alternate pairs of peripheral).

Dimensions.—Shell 0.1 long, 0.14 broad.

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

Family LIII. Tholospyrida, n. fam.

(Pl. 87, figs. 7-10; Pl. 89, figs. 1-4; Pl. 95, figs. 14-16).

Definition.—Spyroidea with a galea, but without thorax; the shell being composed of the bilocular cephalis and of an aboral cupola or galea arising from its coryphal face.

The family Tholospyrida differs from the preceding Zygospyrida, its ancestral group, in the development of a galea, i.e., a fenestrated hemispherical or dome-shaped cupola, which covers the upper face of the cephalis like a cap.

Only three species of this family have been hitherto described: Pylospyris (or Spyridobotrys) trinacria, figured in my Monograph (1862), Pylospyris (or Lithopera) denticulata, figured by Ehrenberg (1872), and Lophospyris (or Ceratospyris) acuminata, figured by Hertwig (1879). Fourteen new species have been found in the collection of the Challenger, which we dispose here among five genera. These may be derived from corresponding genera of Zygospyrida by the development of a galea.

The number and disposition of the terminal feet around the basal plate do not vary so much in the Tholospyrida as in the Zygospyrida. We find here only one genus with three feet, Tholospyris (corresponding to Tripospyris); one genus with two lateral feet, Lophospyris (corresponding to Dipospyris); and two genera with numerous feet, the horned Sepalospyris and the hornless Tiarospyris (the former corresponding to Petalospyris, the latter to Gorgospyris). The fifth genus (Pylospyris) has no feet at all, and may be derived from Circospyris among the Zygospyrida.

The cephalis exhibits in the Tholospyrida the same typical structure which we have described above of all Spyroidea (compare p. 1017). The cupola or galea, arising from its upper face, seems to be a secondary production, perhaps caused by an apical growth of the central capsule, or in other cases by descending branches of the apical horn, which cover the apical face of the calymma with protecting network.

Synopsis of the Genera of Tholospyrida.

I. Subfamily Lophospyrida. Two or three basal (cortinar feet). Galea with a horn.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Three basal feet (two paired pectoral and an odd caudal),	469. Tholospyris.
		Two paired basal (pectoral) feet,	470. Lophospyris.
II. Subfamily Tiarospyrida. Numerous basal feet in a corona (six to nine or more).	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Galea with a horn,	471. Sepalospyris.
		Galea without a horn,	472. Tiarospyris.
III. Subfamily Pylospyrida. No basal feet.	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Galea with a horn,	473. Pylospyris.

Genus 469. Tholospyris,^[29] Haeckel, 1881, Prodromus, p. 441.

Definition.—Tholospyrida with three basal feet and an apical horn.

The genus Tholospyris is probably the common ancestral form of the Tholospyrida, and has arisen from Tripospyris by development of a galea or cupola; this is composed of the apical horn, the lateral branches of which become connected with lateral spines arising from the coryphal face of the cephalis, and of lattice-work developed between the former and the latter. The three descending feet of the basal face are the typical cortinar feet (one odd caudal and two paired pectoral), the same as in the old ancestral genera Cortina, Plagoniscus, Tripospyris, &c.

Subgenus 1. Tholospyrium, Haeckel.

Definition.—Basal feet simple, neither forked nor branched.

1. Tholospyris tripodiscus, n. sp. (Pl. 89, fig. 1).

Shell campanulate, smooth, as broad as long, with deep sagittal stricture. Cephalis compressed, with irregular roundish pores; two or three pairs of larger annular pores on each side of the ring. Basal plate with four large pores. Galea with two very large opposite holes (an occipital and a frontal opening). A slender free perpendicular columella connects the uppermost part of the sagittal ring with the strong three-sided pyramidal apical horn. All three feet of equal length, half as long as the ring, three-sided, prismatic, divergent, with three dentated edges.

Dimensions.—Shell 0.13 diameter, ring 0.08 long, feet 0.05 long.

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

2. Tholospyris fenestrata, n. sp. (Pl. 89, fig. 2).

Shell roundish polyhedral, smooth, with slight sagittal stricture. Cephalis nearly cubical, with irregularly roundish pores; two or three pairs of larger pores on each side of the ring. Basal plate with two very large pores. Galea pyramidal, with two large occipital holes. Columella enclosed in the dorsal wall of the galea, prolonged into an oblique pyramidal spine of the same length. Two pectoral feet pyramidal, nearly vertical and as long as the ring, twice as long as the caudal foot.

Dimensions.—Shell 0.12 diameter, ring 0.07, pectoral feet 0.05 long.

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

3. Tholospyris galeata, n. sp.

Shell helmet-shaped, thorny, with deep sagittal stricture. Cephalis campanulate, with subregular circular pores. Basal plate with three large pores. Galea hemispherical, separated from the cephalis by a sharp horizontal stricture; pores smaller. A slender free columella connects the apex of the ring with the strong conical apical horn, which is half as long as the ring. All three feet of equal length, divergent conical, as long as the horn.

Dimensions.—Shell 0.14 diameter, ring 0.09 long, feet 0.08 long.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

Subgenus 2. Tholospyridium, Haeckel.

Definition.—Basal feet forked or branched.

4. Tholospyris ramosa, n. sp. (Pl. 89, fig. 3).

Shell helmet-shaped, smooth, with deep sagittal stricture. Cephalis nearly spherical, with irregularly polygonal pores; four or five pairs of larger annular pores on each side of the strong angular ring. Cupola flat, conical, with two pairs of larger pores. Columella enclosed in its dorsal wall, bearing an irregularly branched horn. Caudal foot short conical, simple. Two pectoral feet half as long as the shell, angular, subvertical, irregularly branched.

Dimensions.—Shell 0.15 diameter, ring 0.1 long, pectoral feet 0.07 long.

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

5. Tholospyris cupola, n. sp. (Pl. 89, fig. 4).

Shell pear-shaped or cupola-shaped, smooth, with slight sagittal stricture. Cephalis not distinctly separated from the galea, as the ring in the uppermost part of the shell-wall becomes obliterated. Pores irregularly polygonal, small and numerous. Basal plate with four large pores. Apical horn and the three divergent feet, irregularly branched; feet nearly as long as the shell, about four times as long as the horn.

Dimensions.—Shell 0.14 diameter, ring 0.1 long, feet 0.12 long.

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

Genus 470. Lophospyris,^[30] Haeckel, 1881, Prodromus, p. 443 (sensu emendato).

Definition.—Tholospyrida with two lateral basal feet and an apical horn.

The genus Lophospyris differs from the preceding Tholospyris, its probable ancestral form, in the absence of the caudal foot, and therefore bears to it the same relation that Dipospyris does to Tripospyris. The two pectoral feet are alone developed and are placed opposite in the frontal plane. Lophospyris may also be derived from Dipospyris by the formation of a galea.

1. Lophospyris dipodiscus, n. sp. (Pl. 95, fig. 14).

Shell ovate, spinulate, with sharp transverse coronal constriction. Cupola hemispherical, half as large as the nut-shaped cephalis. Pores irregularly roundish, much larger on the sagittal constriction. Apical horn pyramidal, about half as long as the shell. Two lateral feet cylindrical, strongly curved, about as long as the shell, with some irregular branches; together forming a nearly complete circle.

Dimensions.—Shell 0.09 long, 0.08 broad; ring 0.04 long, feet 0.08 long.

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

2. Lophospyris acuminata, Haeckel.

Ceratospyris acuminata, R. Hertwig, 1879, Organism. d. Radiol., p. 70, Taf. vii. fig. 2.

Shell campanulate, smooth, without external transverse stricture. Cupola conical, half as long and broad as the nut-shaped cephalis. Pores irregularly roundish, on each side of the sagittal strictures much larger. Basal plate with four large triangular pores. Apical horn slender, prismatic; its outer free part of the same length as the inner columella, and as the two lateral feet, which are curved, shorter than half the ring.

Dimensions.—Shell 0.08 long, 0.09 broad; ring 0.06 long; horn and feet 0.03 long.

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

3. Lophospyris comosa, n. sp.

Shell ovate, spiny, with deep transverse stricture. Cupola large, campanulate, nearly as long and two-thirds as broad as the nut-shaped cephalis. Pores irregular, roundish, of little different size, Basal plate with numerous (eight to twelve) similar pores. Apical horn large, nearly as long as the shell, surrounded by a bunch of smaller divergent spines. Two lateral feet divergent, larger than the shell, cylindrical; at the distal end irregularly branched, at the base surrounded by some smaller spines.

Dimensions.—Shell 0.15 long, 0.11 broad; ring 0.08 long; feet 0.2 long.

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

Genus 471. Sepalospyris,^[31] Haeckel, 1881, Prodromus, p. 443.

Definition.—Tholospyrida with numerous basal feet (eight to twelve or more). Galea with a horn.

The genus Sepalospyris has been derived from the similar Petalospyris by development of a galea or cupola on the coryphal face of the cephalis, or from Tholospyris by multiplication of the basal feet. The latter (in the two observed species from twelve to twenty-five) form a regular corona around the basal plate.

1. Sepalospyris platyphylla, n. sp. Pl. 95, fig. 15.

Shell ovate, rough, with sharp transverse stricture. Cupola with delicate network, hemispherical, about two-thirds as long and broad as the nut-shaped thorax. Pores of the latter irregular, roundish; two or three pairs of large pores on each side of the sagittal stricture. Apical horn conical, half as long as the shell. Basal coronet with twelve to fifteen broad, lamellar, truncate, vertical feet, somewhat shorter than the cephalis.

Dimensions.—Shell 0.12 long, 0.13 broad; ring 0.06 long; horn 0.04; feet 0.05 long.

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

2. Sepalospyris polyphylla, n. sp.

Shell campanulate, rough, with deep transverse stricture. Cupola hemispherical, about one-third as long and broad as the nut-shaped thorax. Pores irregular, roundish, a little different in size. Apical horn pyramidal, about as long an the shell. Basal coronet with twenty to twenty-five slender, lamellar, pointed, vertical feet, longer than the shell.

Dimensions.—Shell 0.11 long, 0.12 broad; ring 0.07 long; horn 0.1; feet 0.12 to 0.18 long.

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

Genus 472. Tiarospyris,^[32] Haeckel, 1881, Prodromus, p. 443.

Definition.—Tholospyrida with numerous basal feet (eight to twelve or more). Galea without a horn.

The genus Tiarospyris has probably been derived from the preceding Sepalospyris by reduction and loss of the free apical horn; it therefore bears to it the same relation that the similar Gorgospyris does to Petalospyris.

1. Tiarospyris pervia, n. sp. (Pl. 87, fig. 7).

Shell nut-shaped, smooth, with deep sagittal stricture. Cephalis on the lateral sides with numerous small roundish pores, on each side of the ring with a pair of very large holes. Basal plate with two large collar pores. Cupola flat, cap-shaped, with two large parietal pores above the ring. Coronet with eight conical, slightly divergent feet, about one-fourth as long as the shell.

Dimensions.—Shell 0.08 long, 0.1 broad; ring 0.06 long; feet 0.02 long.

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

2. Tiarospyris galea, n. sp.

Shell helmet-shaped, with deep sagittal stricture. Cephalis with irregular, polygonal pores; on each side of the ring two pairs of larger annular pores. Basal plate with four large pores. Cupola high, conical, nearly as long as the cephalis, separated from it by a distinct coronal stricture. Basal coronet with twelve to sixteen slender curved divergent feet, nearly as long as the shell.

Dimensions.—Shell 0.16 long, 0.12 broad; ring 0.1 long; feet 0.15 long.

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

3. Tiarospyris mitra, n. sp. (Pl. 87, figs. 9, 10).

Shell subspherical, smooth. Cephalis on the lateral sides with small roundish, double-contoured pores, on each side of the ring with three to five pairs of larger pores, each of which is closed by a thin fenestrated lamella (different on the frontal face, fig. 9, and the dorsal face, fig. 10). Cupola flat, cap-shaped, separated by a distinct coronal stricture, with similar pores. Basal coronet with, ten to twelve short conical convergent feet.

Dimensions.—Shell 0.11 long, 0.12 broad; ring 0.04 long; feet 0.02 long.

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

4. Tiarospyris amphora, n. sp. (Pl. 87, fig. 8).

Shell amphora-shaped, in the upper half smooth, in the lower spiny, without external sagittal stricture. Cephalis subspherical with a small number of irregular, large, roundish pores, which are closed by a thin fenestrated lamella. Cupola flat, cap-shaped, with numerous small pores. Base covered with numerous conical divergent feet of different sizes, the largest one-third as long as the shell. Internal sagittal ring ovate, nearly free.

Dimensions.—Shell 0.14 long, 0.13 broad; ring 0.1 long; feet 0.04 long.

Habitat.—South Pacific, Station 285, depth 2375 fathoms.

Genus 473. Pylospyris,^[33] Haeckel, 1881 Prodromus, p. 443.

Definition.—Tholospyrida without basal feet, with an apical horn.

The genus Pylospyris was first known from a Mediterranean species, called by me, in 1862, Spyridobotrys trinacria. As this name was given erroneously, on the supposition of a near relation to the Botryodea (= Polycyrtida), I changed it afterwards to Pylospyris. This genus differs from the other Tholospyrida in the total absence of basal feet, and may therefore be derived either from them by reduction of the feet, or from Dictyospyris by formation of a galea.

1. Pylospyris denticulata, Haeckel.

Lithopera denticulata, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 297, Taf. xii. II. fig. 7. Lithobotrys denticulata, Ehrenberg, 1844, Monatsber. d. Akad. Berlin, p. 203.

Shell spinulate, with slight coronal and deep sagittal constriction, with irregular, roundish pores of variable size. Galea hemispherical, about half as long and broad as the nut-shaped cephalis. No symmetrically disposed larger pores.

Dimensions.—Galea 0.04 long, 0.06 broad; cephalis 0.08 long, 0.1 broad.

Habitat.—Antarctic Ocean, Ehrenberg. (Included in the ice.)

2. Pylospyris trinacria, Haeckel.

Spyridobotrys trinacria, Haeckel, 1862, Monogr. d. Radiol., p. 341, Taf. xii. figs. 8, 9.

Shell tuberculate, with sharp coronal and sagittal stricture. Galea campanulate, with very small circular pores, and a short conical apical horn of the same length. Cephalis nut-shaped, with large, irregular, roundish pores; two pairs of larger annular pores on each side of the sagittal ring, also four larger pores in the basal plate.

Dimensions.—Galea 0.03 long, 0.04 broad; cephalis 0.04 long, 0.07 broad.

Habitat.—Mediterranean, Messina, surface.

3. Pylospyris canariensis, n. sp. (Pl. 95, fig. 16).

Shell rough, with deep coronal and slight sagittal constriction. Galea hemispherical, with numerous small irregular, roundish pores, about half as long as the cephalis, with a slender conical horn of twice the length. Cephalis nut-shaped, with larger roundish pores of very unequal size, three pairs of larger pores on each side of the ring. Basal plate with two larger pores.

Dimensions.—Galea 0.03 long, 0.08 broad; cephalis 0.06 long, 0.11 broad.

Habitat.—North Atlantic, Canary Islands, surface.

Family LIV. Phormospyrida, Haeckel (sensu emendato) (Pl. 83, figs. 13-15; Pl. 95, figs. 17-19).

Phormospyrida, Haeckel, 1881, Prodromus, p. 442.

Definition.—Spyroidea with a thorax, without galea; the shell composed of the bilocular cephalis and of a simple thorax arising from its basal face.

The family Phormospyrida differs from the Zygospyrida, their ancestral group, in the development of a thorax, or a second fenestrated shell-joint, which arises from the lower face of the cephalis. It corresponds, therefore, to the Dicyrtida among the Cyrtoidea, and may perhaps be, wholly or partially, the ancestral group of the latter. When the sagittal ring and the longitudinal constriction of the cephalis disappear, the Phormospyrida pass over into the Dicyrtida.

Only three species of this family have been hitherto known, which were found fossil in Barbados, and described by Ehrenberg (1875) as Lithobotrys stiligera and Petalospyris confluens, and by Bütschli (1882) as Petalospyris anthocyrtoides. Fifteen other species are found in the Challenger collection, which we dispose here among five genera.

Two of these five genera (the horned Acrospyris and the hornless Phormospyris) possess the three typical basal feet of Cortina and Tripospyris, and may be derived from these genera by the development of network between the bases of the feet. The three other genera possess numerous feet, and may be derived in the same way from the Polyspyrida; the apical face differs in the three genera, in Desmospyris it is hornless, in Patagospyris it bears an apical horn, and in Rhodospyris three horns (an apical and two lateral or frontal).

The cephalis in the Phormospyrida exhibits the same typical structure, which we have described above, of all Spyroidea (compare, p. 1017). The thorax or the second joint of the shell arises by reticular connection of the bases of the basal feet, and represents a cylindrical or truncate-conical joint in the polypodal forms, or a three-sided joint in the tripodal forms. The terminal aperture or the mouth of the thorax is constantly open, and surrounded by the free ends of the feet.

Synopsis of the Genera of Phormaspyrida

I. Subfamily Acrospyrida. Three basal cortinar feet (one odd caudal and two paired pectoral).	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	One apical horn,	474. Acrospyris.
		No apical horn,	475. Phormospyris.
II. Subfamily Rhodospyrida. Numerous basal feet in a corona (nine to twelve or more.)	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	One apical horn,	476. Patagospyris.
		Three apical horns,	477. Rhodospyris.
		No apical horn,	478. Desmospyris.

Subfamily 1. Acrospyrida, Haeckel, 1881, Prodromus, p. 441 (sensu emendato).

Definition.—Phormospyrida with three basal feet (an odd caudal and two paired pectoral).

Genus 474. Acrospyris,^[34] Haeckel, 1881, Prodromus, p. 441.

Definition.—Phormospyrida with three basal feet and one apical horn.

The genus Acrospyris is probably the oldest and most primitive among the Phormospyrida, perhaps the original ancestral form of this family. It has been derived from Tripospyris by the development of lattice-work between the three basal feet, forming a second joint or thorax. It has also therefore a close relation to the simplest forms of the triradiate Dicyrtida: Dictyophimus, Clathrocanium, &c. It differs from these in the distinct sagittal constriction of the cephalis, which divides it into two lateral loculi.

1. Acrospyris clathrocanium, n. sp. (Pl. 95, fig. 17).

Shell tuberculate, with distinct collar and deep sagittal stricture. Cephalis nut-shaped, with numerous irregular, roundish pores; three pairs of larger annular pores on each side of the ring. Basal plate with four larger pores (two major cardinal and two minor jugular pores). Apical horn slender, pyramidal, curved, about as long as the shell, with three recurved short spines. Thorax three-sided, about twice as large as the cephalis, with three large basal holes and a broad riband with numerous smaller holes; three ribs between them stout, pyramidal, strongly curved, prolonged into three convergent crescentic feet.

Dimensions.—Cephalis 0.08 long, 0.11 broad; thorax 0.14 long, 0.16 broad.

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

2. Acrospyris dictyophimus, n. sp.

Shell smooth. Cephalis and thorax of nearly the same structure and form as in the preceding species; it differs from the latter in the shape of the three stout basal feet, which are straight, much longer than the thorax, divergent, and at the broader base irregularly fenestrated, without three larger holes.

Dimensions.—Cephalis 0.05 long, 0.08 broad; thorax 0.07 long, 0.12 broad.

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

3. Acrospyris pyramidalis, n. sp.

Shell three-sided pyramidal, with slight collar stricture. Cephalis campanulate, with deep sagittal stricture and stout ring, armed with a strong pyramidal horn of the same length. Thorax shorter and broader, truncate. Pores irregular, roundish, scarce. Three feet divergent, three-sided pyramidal, as long as the cephalis.

Dimensions.—Cephalis 0.05 long, 0.06 broad; thorax 0.02 long, 0.08 broad.

Habitat.—Fossil in Barbados.

4. Acrospyris macrocephala, n. sp.

Shell spinulate, with deep sagittal and very deep collar stricture. Cephalis very large, nut-shaped, twice as long and broad as the small, truncate, pyramidal thorax. Pores irregular, roundish. Horn spindle-shaped, nearly as long as the cephalis; the three divergent feet are of the same form and size as the horn, and arise as three ribs from the deep collar stricture.

Dimensions.—Cephalis 0.1 long, 0.15 broad; thorax 0.05 long, 0.09 broad.

Habitat.—Fossil in Barbados.

5. Acrospyris fragilis, n. sp.

Shell very thin-walled and fragile, with deep sagittal and collar strictures. Pores very small and numerous, circular. Cephalis nut-shaped, nearly spherical, with a slender bristle-shaped horn of the same length. Basal stricture with two large collar pores only (luminella). Thorax nearly three-sided prismatic, longer than the cephalis, with three parallel ribs, prolonged into three slender, long, bristle-shaped feet.

Dimensions.—Cephalis 0.05 long, 0.06 broad; thorax 0.08 long, 0.06 broad.

Habitat.—North Pacific, Station 244, surface.

Genus 475. Phormospyris,^[35] Haeckel, 1881, Prodromus, p. 442 (sensu emendato).

Definition.—Phormospyrida with three basal feet, without apical horn.

The genus Phormospyris has been derived from Acrospyris, its ancestral form, by reduction and loss of the apical horn; it therefore bears to the latter the same relation that Tristylospyris has to the ancestral Tripospyris.

1. Phormospyris tricostata, n. sp. (Pl. 83, fig. 15).

Cephalis nut-shaped, thorny, with deep sagittal and collar strictures, half as large as the pyramidal thorax. Mouth of the latter dilated and ciliated, twice as broad as the cephalis. Pores irregular, polygonal, with thin bars. Three cylindrical, straight, divergent ribs descend in the wall of the thorax, and are prolonged over the mouth into three short conical teeth.

Dimensions.—Cephalis 0.06 long, 0.09 broad; thorns 0.08 long, 0.16 broad.

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

2. Phormospyris tridentata, n. sp. (Pl. 95, fig. 18).

Cephalis nut-shaped, with deep sagittal and collar strictures, about twice as large as the thorax. Mouth of the latter half as broad as the cephalis. Pores very small and numerous, subregular, circular. Collar plate with four large triangular pores. In the wall of the thorax three vertical prismatic ribs descend, which are prolonged over the mouth into three parallel feet of the same length.

Dimensions.—Cephalis 0.06 long, 0.08 broad; thorns 0.04 long, 0.06 broad.

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

3. Phormospyris trifoliata, n. sp.

Cephalis nut-shaped, with deep sagittal and collar strictures, smaller than the thorax. Mouth of the latter nearly as broad as the cephalis. Pores circular, double-contoured, larger in the thorax than in the cephalis. The thorax has no lateral ribs, but bears around the mouth three large triangular lamellar terminal feet.

Dimensions.—Cephalis 0.04 long, 0.05 broad; thorax 0.06 long, 0.05 broad.

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

Subfamily 2. Rhodospyrida, Haeckel.

Definition.—Phormospyrida with a corona of numerous (nine to twelve or more) basal feet.

Genus 476. Patagospyris,^[36] Haeckel, 1881, Prodromus, p. 443.

Definition.—Phormospyrida with numerous basal feet (nine to twelve or more) and an apical horn.

The genus Patagospyris and the two following closely allied genera differ from the two preceding tripodal genera in the multiplication of the basal feet, and therefore have to the latter the same relation that the Polyspyrida (Petalospyris) bear to the Tripospyrida (Tripospyris). When the numerous basal feet of Petalospyris become connected by lattice-work, Patagospyris arises.

1. Patagospyris confluens, Haeckel.

Petalospyris confluens, Ehrenberg, 1885, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 80, Taf. xxii. fig. 5.

Shell tuberculate, with distinct sagittal and collar strictures. Pores irregular, roundish. Cephalis nut-shaped, larger than the short truncate thorax. Horn conical, shorter than the cephalis. Peristome with a coronet of twelve to fifteen short triangular feet, which are parallel and vertical, slightly curved and shorter than the thorax.

Dimensions.—Cephalis 0.05 long, 0.07 broad; thorax 0.03 long, 0.07 broad.

Habitat.—Fossil in Barbadoes.

2. Patagospyris lanceolata, n. sp.

Shell tuberculate, with slight sagittal and sharp collar strictures. Pores subregular, circular. Cephalis subspherical, about as large as the truncate subcylindrical thorax. Horn spindle-shaped, about as long as the cephalis. Peristome with a coronet of fifteen to twenty divergent lanceolate lamellar feet, longer than the thorax.

Dimensions.—Cephalis 0.08 long, 0.09 broad; thorax 0.07 long, 0.07 broad.

Habitat.—Fossil in Barbados.

3. Patagospyris stiligera, Haeckel.

Lithobotrys stiligera, Ehrenberg, 1875, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 76, Taf. iii. fig. 17.

Shell smooth, hyaline, with deep sagittal and collar strictures. Pores very small and few. Cephalis nut-shaped, bilobed, of the same breadth as the cylindrical thorax. Horn conical, about as long as the cephalis. Peristome with a coronet of six to nine broad lamellar feet (in Ehrenberg's figure broken off).

Dimensions.—Cephalis 0.04 to 0.05 diameter; thorax 0.06 long, 0.05 broad.

Habitat.—Fossil in Barbados.

4. Patagospyris anthocyrtis, n. sp. (Pl. 95, fig. 19).

Shell smooth, with deep sagittal and deep collar strictures. Pores irregular, roundish, of various sizes, numerous. Cephalis nut-shaped, with two inflated bosoms, about twice as broad as the short cylindrical thorax. Horn stout, pyramidal, about as long as the cephalis. Peristome with a coronet of fifteen to twenty parallel and vertical triangular lamellar feet, nearly as long as the thorax.

Dimensions.—Cephalis 0.05 long, 0.1 broad; thorax 0.04 long, 0.06 broad.

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

Genus 477. Rhodospyris,^[37] Haeckel, 1881, Prodromus, p. 443.

Definition.—Phormospyrida with numerous basal feet (nine to twelve or more), and with three coryphal horns.

The genus Rhodospyris differs from the preceding Patagospyris in the development of three coryphal horns (one odd middle apical horn, and two paired frontal horns on each of its sides), and therefore bears the same relation to the latter that the similar Anthospyris does to Petalospyris. When the numerous basal feet of Anthospyris become connected by lattice-work, Rhodospyris arises.

1. Rhodospyris tricornis, n. sp. (Pl. 83, fig. 13).

Cephalis nut-shaped, with deep sagittal stricture, and three short apical horns of half its length; the middle odd horn is straight, the two paired lateral horns are curved outwards. Thorax somewhat larger than the cephalis, dilated around the wide open mouth, with a coronet of twenty-five to thirty slender basal feet, which are slightly curved and convergent, about as long as the thorax. Pores small, numerous and circular.

Dimensions.—Cephalis 0.05 long, 0.07 broad; thorax 0.06 long, 0.08 broad; horns 0.02 long, feet 0.06 long.

Habitat.—Indian Ocean, Madagascar (Rabbe), surface.

2. Rhodospyris triceros, n. sp.

Cephalis nut-shaped, with deep sagittal and deep collar stricture, and with three stout divergent horns of nearly equal length. Thorax cylindrical, twice as long as the cephalis, and of the same breadth, with a coronet of twelve to sixteen broad, lamellar, rectangular, perpendicular feet around the mouth, about as long as the cephalis. Pores rather large, subregular, circular.

Dimensions.—Cephalis 0.06 long, 0.08 broad; thorax 0.12 long, 0.09 broad.

Habitat.—Indian Ocean, Singapore (Trebing), surface.

Genus 478. Desmospyris,^[38] Haeckel, 1881, Prodromus, p. 443.

Definition.—Phormospyrida with numerous basal feet (nine to twelve or more), without a coryphal horn.

The genus Desmospyris differs from the two preceding polypodal genera in the complete absence of horns on the coryphal face of the cephalis. It therefore corresponds to Gorgospyris among the Zygocyrtida, and arises when the numerous basal feet of the latter become connected by lattice-work.

1. Desmospyris mammillata, n. sp. (Pl. 83, fig. 14).

Shell mammillate, with deep sagittal and slight collar constriction. Pores irregular, roundish. Cephalis nut-shaped, larger than the inversely conical thorax, and twice as broad as the constricted mouth. Coronet of the peristome with twelve to fifteen short conical convergent feet, shorter than half the thorax.

Dimensions.—Cephalis 0.06 long, 0.09 broad; thorax 0.04 long, 0.06 broad.

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

2. Desmospyris cyrtocolpos, n. sp.

Shell smooth, with deep sagittal and collar strictures. Pores subregular, circular, double-contoured, very small and numerous. Cephalis nut-shaped, larger than the short truncate thorax. Coronet with eighteen to twenty-four slender, irregular, pointed, convergent feet, about twice as long as the thorax.

Dimensions.—Cephalis 0.08 long, 0.12 broad; thorax 0.04 long, 0.1 broad.

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

3. Desmospyris anthocyrtoides, Haeckel.

Petalospyris anthocyrtoides, Bütschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. pp. 533, 539, Taf. xxxii. fig. 19, a-c.

Shell tuberculate, with slight sagittal and sharp collar strictures. Pores subregular, circular. Cephalis nut-shaped, larger than the short truncate thorax. Coronet with fifteen to twenty short conical, parallel and vertical feet, about as long as the thorax.

Dimensions.—Cephalis 0.06 long, 0.09 broad; thorax 0.02 long, 0.07 broad.

Habitat.—Fossil in Barbados.

4. Desmospyris carpocanium, n. sp.

Shell smooth, with slight sagittal and slight collar strictures. Pores subregular, circular, small and numerous. Cephalis campanulate, smaller than the ovate thorax. Coronet with fifteen to twenty irregular lamellar feet, which are longer than the thorax, pointed, nearly vertical and parallel.

Dimensions.—Cephalis 0.05 long, 0.08 broad; thorax 0.07 long, 0.1 broad.

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

Family LV. Androspyrida, n. fam. (Pl. 88-90).

Definition.—Spyroidea with galea and thorax; the shell composed of a bilocular cephalis and of two secondary joints, a galea arising from its upper face, and a thorax arising from its lower face.

The family Androspyrida differs from the three preceding families of Spyroidea in the three-jointed shell, in which the galea of the Tholospyrida and the thorax of the Phormospyrida are combined; it may therefore be derived from the latter by development of a galea, or from the former by formation of a thorax. The common ancestral group of these three families is probably the Zygospyrida. But it may be that a part of the Androspyrida has originated directly from the Stephoidea.

Two species only of this family were hitherto known, Amphispyris reticulata (figured, in 1872, by Ehrenberg, as Dictyospyris) and Sphærospyris sphæra (described, in 1882, by Bütschli, as Dictyospyris). Thirty new species were found in the collection of the Challenger, and are here disposed in seven genera. But perhaps these may represent three different families, which we here enumerate as subfamilies; the Lamprospyrida, Perispyrida, and Nephrospyrida.

The Lamprospyrida, the first subfamily, are tripodal Spyroidea with galea and thorax; they may therefore be regarded as a combination of Tholospyris and Acrospyris. In the simpler form, Androspyris (Pl. 83, fig. 8), the network of the shell is simple, and allows a very clear recognition of the internal structure. In the splendid Lamprospyris, derived from it (Pl. 89, figs. 13, 14) the delicate network is more or less spongy. The large apical horn is branched and fenestrated in the latter and simple in the former.

The Perispyrida, the second subfamily, possess no free apophyses, but a three-jointed shell with two distinct transverse strictures, an upper mitral and a lower collar stricture. The network of this shell is incomplete in Amphispyris (Pl. 88, figs. 2-7), being developed only in the frontal or lateral perimeter, thus making it probable that this subfamily may have arisen directly from the Tympanida (Toxarium, Pl. 88, fig. 1; Pl. 93, figs. 18-20). The network of Tricolospyris (Pl. 88, figs. 8-11) is complete, of another shape in the cephalis than in the galea and thorax; it is doubled or spongy in Perispyris (Pl. 88, figs. 12, 13).

The Nephrospyrida, the third subfamily, contains two very different genera only, each of which may represent a separate family. Sphærospyris (Pl. 83, fig. 4) possesses a spherical or subspherical lattice-shell, the central part of which includes a sagittal ring, connected with the inner face of the sphere by a number of paired apophyses, corresponding to those of Lithocircus; it may be easily confounded with some Sphæroidea (Carposphæra), but the enclosed ring leaves no doubt as to its true origin. Nephrospyris (Pl. 90) has a flat discoidal shell of considerable size, usually kidney-shaped or cordate, with a deep sagittal incision at the base, indicating the region where the pseudopodia are protruded from the porochora. The violin-shaped central capsule has two large lateral lobes on each side of the including sagittal ring, and the transverse nucleus is perpendicular to its sagittal plane (Pl. 90, figs. 7, 10). Sphærocircus as well as Nephrospyris have probably arisen independently from the Stephanida.

Synopsis of the Genera of Androspyrida.

I. Subfamily Lamprospyrida. Three free basal feet.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Lattice-work simple, not spongy.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Apical horn usually simple, not fenestrated,	479. Androspyris.
		Lattice-work wholly or partly spongy.	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Apical horn usually branched and fenestrated,	480. Lamprospyris.
II. Subfamily Perispyrida. No free basal feet. Shell three-jointed.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Shell with two transverse coronal strictures (one superior mitral and one inferior collar stricture).	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \\\ \ \end{matrix}}\right.}$	Lattice-work only complete in the frontal ring,	481. Amphispyris.
				Lattice-work complete on all sides,	482. Tricolospyris.
				Lattice-work double or spongy,	483. Perispyris.
III. Subfamily Nephrospyrida. No free basal feet. Shell spherical or discoidal.	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$	Shell without external transverse stricture.	$\scriptstyle {\left\{{\begin{matrix}\ \\\\\ \ \end{matrix}}\right.}$	Shell spherical or subspherical,	484. Sphærospyris.
				Shell discoidal, kidney-shaped or subcircular,	485. Nephrospyris.

Subfamily 1. Lamprospyrida, Haeckel.

Definition.—Androspyrida with three free basal feet (an odd posterior caudal foot and two paired anterior pectoral feet).

Genus 479. Androspyris,^[39] n. gen.

Definition.—Androspyrida with three free basal feet and a simple apical horn; lattice-work of the three-jointed shell simple, not spongy.

The genus Androspyris is probably the most original form of the Androspyrida, and represents, together with the following Lamprospyris, the subfamily of Lamprospyrida, which always possess three free basal feet, an odd posterior or caudal foot, and two paired anterior or pectoral feet. It may be derived either from Acrospyris by development of a cupola, or from Tholospyris by development of a thorax; the common ancestral form of these three typical genera is, no doubt, Tripospyris. Some species of Androspyris reach a considerable size and are distinguished by a peculiar external form resembling somewhat a human figure.

1. Androspyris homunculus, n. sp.

Shell thorny, with two deep transverse constrictions and irregular polygonal pores. Galea subspherical, with a strong pyramidal oblique horn, about two-thirds as large as the cephalis, which has the form of a human thorax, includes a strong ovate sagittal ring, and bears on each side a stronger lateral spine. Thorax short and broad, prolonged into three latticed divergent feet; the two lateral (pectoral) feet are like the legs of a human body, and are twice as long as the cephalis and as the tail-like caudal feet. (The whole shell exhibits a curious similarity to a human figure, more than in the following nearly allied species.)

Dimensions.—Length of the shell (including horn and feet) 0.4, breadth 0.1 to 0.15.

Habitat.—Central Pacific, Station 273, depth 2350 fathoms.

2. Androspyris anthropiscus, n. sp. (Pl. 83, fig. 8).

Shell rough, with two distinct transverse constrictions and irregular polygonal pores. Galea ovate, with a slender conical oblique horn, about as large as the cephalis, which exhibits a deep longitudinal furrow in the sagittal dorsal line. Thorax half as long, prolonged into three short latticed feet; the terminal spines of the two lateral feet are vertical and parallel, that of the caudal foot larger, directed obliquely backwards.

Dimensions.—Length of the shell (including horn and feet) 0.35, breadth 0.1 to 0.12.

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

3. Androspyris pithecus, n. sp. (Pl. 95, fig. 20).

Shell smooth, with two slight transverse constrictions. Galea conical, with a short conical horn, longer than the nut-shaped cephalis. Thorax with three nearly vertical and parallel feet of equal length. Pores in the galea and thorax very small and numerous, circular, in the cephalis much larger, irregular, roundish.

Dimensions.—Length of the shell (including horns and feet) 0.25, breadth 0.06 to 0.08.

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

4. Androspyris aptenodytes, n. sp.

Shell smooth, with two slight transverse constrictions and irregular, roundish pores. Galea hemispherical, with a short conical horn, about as large as the roundish cephalis and half as large as the ovate thorax. The three feet arise immediately beyond the collar stricture, are equal, divergent, curved, about as long as the cephalis, and are not terminal (as in the three preceding species), but lateral appendages of the thorax.

Dimensions.—Length of the shell 0.2, breadth 0.05 to 0.07.

Habitat.—Antarctic Ocean, Station 157, depth 1950 fathoms.

Genus 480. Lamprospyris,^[40] Haeckel, 1881, Prodromus, p. 447.

Definition.—Androspyrida with three free basal feet and a fenestrated apical horn; lattice-work of the three-jointed shell wholly or partly spongy.

The genus Lamprospyris differs from the preceding Androspyris, its ancestral form, mainly in the higher development of the lattice-work of the large shell. Whilst this in the latter genus is a simple lattice-plate, it here becomes more or less spongy, and sometimes forms a very dense and delicate wickerwork. The apical horn and the three basal feet are commonly also fenestrated. The two annular strictures, which separate the cephalis from the conical cupola and the inflated thorax, are commonly not so distinct as in the preceding genus. Some species belong to the largest Spyroidea and reach more than half a millimetre in length.

1. Lamprospyris darwinii, n. sp. (Pl. 89, fig. 13).

Shell nearly pear-shaped, with two distinct annular strictures, and uneven papillate surface. The total length is equal to twice the greatest breadth, and to seven times the length of the ring. Apical horn free, irregularly branched and fenestrated, as long as the included columella beyond it. The three diverging feet are strongly curved, S-shaped, and completely included by loose lattice-work. In the middle of their length they give off a simple strong lateral branch. The loose arachnoidal lattice-work is rather equally developed.

Dimensions.—Length of the entire shell (including the apophyses) 0.5, greatest breadth 0.25, ring 0.07 long.

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

2. Lamprospyris lyellii, n. sp.

Shell slender, pear-shaped, very similar to the preceding species, but differing in the following characters—the branched horn is much larger and twice as long as the columella; the two annular transverse strictures (separating the three joints) are deeper. The free internal branches of the three included feet are forked. Lattice-work looser than in the preceding species.

Dimensions.—Length of the entire shell 0.6, breadth 0.2, ring 0.09 long.

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

3. Lamprospyris huxleyi, n. sp. (Pl. 89, fig. 14).

Shell ovate, spiny, with two slight annular transverse strictures; their length equal to one and a half times the breadth, and up to seven times the length of the ring. Apical horn quite included by the loose lattice-work of the large conical cupola, which is as long as the cephalis and thorax together. The three slender feet are also included in the lattice-work and only one-third as long as the shell, nearly vertical. Lattice-work much denser than in the two preceding species.

Dimensions.—Length of the shell 0.4, breadth 0.26, ring 0.06 long.

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

4. Lamprospyris hookeri, n. sp.

Shell ovato-conical, very similar to the preceding species, but smooth, not spiny. The apical horn and the three feet are much longer, not included in the network, but freely prominent, half as long as the shell and nearly vertical, parallel. The arachnoidal lattice-work is much denser in the middle third (cephalis) than in the upper third (cupola) of the lower third (thorax).

Dimensions.—Length of the shell (without appendages) 0.45, breadth 0.3, ring 0.08 long.

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

5. Lamprospyris spenceri, n. sp.

Shell slender, ovate, very similar to the preceding species; differing from it in the larger cupola, which is as long as the cephalis and thorax together. The three feet are much shorter and weaker, more divergent. This differs from all four preceding species in the possession of a large double apical horn; the two horns are strong, pyramidal, straight, strongly divergent, and as long as the cupola.

Dimensions.—Length of the shell (without the appendages) 0.3, breadth 0.2, ring 0.05 long.

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

Subfamily 2. Perispyrida, Haeckel, 1881, Prodromus, p. 443.

Definition.—Androspyrida without free basal feet, with three distinct joints separated by two parallel transverse strictures.

Genus 481. Amphispyris,^[41] Haeckel, 1881, Prodromus, p. 444.

Definition.—Androspyrida without free basal feet, with three distinct joints, separated by two transverse strictures; lattice-work of the shell only complete in the frontal ring, with large open holes on the ventral and dorsal face.

The genus Amphispyris and the two following genera arising from it, represent together the peculiar small subfamily of Perispyrida. This may have originated directly from Toxarium (family Tympanida, Pl. 88, fig. 1; Pl. 93, figs. 18-20), the large holes between its arches and rings becoming filled up by lattice-work; in Amphispyris this intercalated network remains incomplete on the ventral and dorsal faces, whilst in Tricolospyris it becomes complete, and in Perispyris spongy.

Subgenus 1. Amphispyrium, Haeckel.

Definition.—On each side of the ring-plane three pairs of large annular meshes; no middle zygomatic ring is developed between the two tympanic transverse rings (superior orbital and inferior maxillary ring).

1. Amphispyris thorax, n. sp. (Pl. 88, fig. 4).

Shell thorax-shaped, as long as broad, with a deep sternal incision and two slight transverse strictures. On each side of the ring-plane three pairs of large, irregular, annular holes of nearly equal size, the middle holes nearly half as broad as the shell. No zygomatic bars between the orbital and maxillary bars. Lateral lattice-girdle narrow, with few small roundish meshes.

Dimensions.—Shell 0.17 long, 0.17 broad, ring 0.06 long.

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

2. Amphispyris quadrigemina, n. sp. (Pl. 88, fig. 6).

Shell shaped like the "corpora quadrigemina cerebralia," with two deep crossed strictures, a coronal transverse stricture and a sagittal sternal stricture. On each side of the ring plane three pairs of large, irregular, annular, double holes, the middle holes larger than the upper and lower holes, and about one-fourth as long as the shell. No zygomatic bars between the orbital and maxillary bars. Lateral lattice-girdle broad, with numerous small meshes.

Dimensions.—Shell 0.13 long, 0.16 broad, ring 0.07 long.

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

3. Amphispyris reticulata, Haeckel.

Dictyospyris reticulata, Ehrenberg, 1872, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 289, Taf. x. fig. 19.

Shell thorax-shaped, one and one-fifth times as long as broad, with a deep sternal incision and two distinct transverse strictures. On each side of the ring-plane three pairs of large annular holes of nearly equal size, about one-third as long as the shell. No zygomatic bars between the orbital and maxillary bars. Lateral girdle narrow, with few large polygonal meshes.

Dimensions.—Shell 0.18 long, 0.15 broad.

Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).

Subgenus 2. Amphispyridium, Haeckel.

Definition.—On each side of the ring-plane four pairs of larger annular meshes; a middle horizontal zygomatic ring is developed between the two tympanic transverse rings (superior orbital and inferior maxillary ring).

4. Amphispyris sternalis, n. sp. (Pl. 88, fig. 2).

Shell thorax-shaped, one and one-fifth times as long as broad, with deep sternal incision and two distinct transverse (tympanic) strictures. On each side of the ring-plane four pairs of large irregular, annular holes; the fourth (inferior or buccal) pair is the longest. The middle of the sagittal ring is crossed by horizontal zygomatic bars (between the ascending orbital and the descending maxillary bars). Lateral lattice-girdle narrow, with few large meshes.

Dimensions.—Shell 0.24 long, 0.2 broad; ring 0.09 long.

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

5. Amphispyris subquadrata, n. sp. (Pl. 88, fig. 5).

Shell compressed, nearly square, spiny, with slight sternal incision and two distinct transverse strictures. Similar to the preceding species; four pairs of irregular annular pores of nearly equal size. Zygomatic ring complete. Lateral lattice-girdle narrow, with few large meshes.

Dimensions.—Shell 0.14 long, 0.12 broad; ring 0.06 long.

Habitat.—Central Pacific, Station 285, depth 2275 fathoms.

6. Amphispyris costata, n. sp. (Pl. 88, fig. 3).

Shell compressed, nearly square, with slight sternal incision and two obliterated transverse strictures. Similar to the two preceding species; with four pairs of large annular pores, the two middle of which (the orbital and nasal holes) are much larger than the superior (frontal) and inferior (oral) holes. Zygomatic ring incomplete. Lateral lattice-girdle broad, with very numerous, small, irregular, polygonal pores.

Dimensions.—Shell 0.2 long, 0.16 broad; ring 0.07 long.

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

7. Amphispyris toxarium, n. sp. (Pl. 88, fig. 7).

Shell inflated, with deep sternal incision and two distinct transverse strictures. Similar to the preceding species, but with deeper constriction and looser lattice-work. Four pairs of large, irregular, annular pores, the central two of which are much larger. Zygomatic ring complete. Lateral girdle broad, with irregular pores of very different size.

Dimensions.—Shell 0.2 long, 0.14 broad; ring 0.09 long.

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

Genus 482. Tricolospyris,^[42] Haeckel, 1881, Prodromus, p. 443.

Definition.—Androspyrida without free basal feet, with three distinct joints, separated by two transverse strictures; lattice-work of the shell complete, simple.

The genus Tricolospyris has arisen from the preceding Amphispyris, its ancestral form, by development of lattice-work which completely closes the large open holes remaining on the ventral and dorsal faces of the latter.

1. Tricolospyris kantiana, n. sp. (Pl. 88, fig. 10).

Shell smooth, one and a half times as long as broad, with two deep transverse strictures. Pores of the cephalis large, roundish, of nearly equal size. Cupola and thorax hemispherical, of about the same size and form, with numerous and small, double-contoured, roundish pores.

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

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

2. Tricolospyris leibnitziana, n. sp. (Pl. 88, fig. 9).

Shell spiny, twice as long as broad, with two deep transverse strictures. Pores of the cephalis large, roundish, polygonally framed, of very different size; two middle transverse rows of smaller pores enclosed between a superior and an inferior row of very large pores. Cupola and thorax hemispherical, about equal, with much smaller and very numerous roundish pores.

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

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

3. Tricolospyris baconiana, n. sp. (Pl. 88, fig. 8).

Shell rough, twice as long as broad, with two sharp strictures. Pores of the cephalis large, very irregular, partly lobated. Cupola hemispherical, smaller than the campanulate thorax, both with smaller irregular pores.

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

Habitat.—Western Tropical Pacific, Station 215, depth 2500 fathoms.

4. Tricolospyris newtoniana, n. sp. (Pl. 88, fig. 11).

Shell spiny, slender, three times as long as broad, with two distinct strictures. Pores of the cephalis very large, irregular. Cupola hemispherical, only one-third as long as the slender inversely conical abdomen, both with irregular, much smaller pores.

Dimensions.—Shell 0.22 long, 0.08 broad; ring 0.05 long.

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

Genus 483. Perispyris,^[43] Haeckel, 1881, Prodromus, p. 444.

Definition.—Androspyrida without free basal feet, with three distinct joints, separated by two transverse strictures; lattice-work of the shell double or spongy.

The genus Perispyris differs from the preceding Tricolospyris, its ancestral form, in the development of a secondary outer shell, which encloses the inner primary one either like an enveloping cortical shell or like a spongy veil. This is produced by the concrescence of meeting branches, which arise from spines of the inner shell.

1. Perispyris bicincta, n. sp. (Pl. 88, fig. 13).

Shell smooth, with two deep transverse annular strictures and a deep sagittal incision at the sternal base; one and a half times as long as broad. Cephalis nut-shaped, with large irregular roundish pores and very broad bars. Everywhere from its surface there arise numerous slender arborescent radial beams; by the anastomoses of their ramified branches there arise the flat cap-shaped cupola and the larger bilobed thorax; and also the external enveloping shell with loose delicate network.

Dimensions.—Inner shell 0.17 long, 0.1 broad; outer shell 0.23 long, 0.17 broad; ring 0.06 long.

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

2. Perispyris spongiosa, n. sp.

Shell rough, with two distinct transverse strictures and a deep sternal incision, similar to the preceding; the radial beams arising from the inner shell, and forming by anastomosing branches the outer shell, are thinner and more numerous, and the framework of the latter on the surface is very dense and spongy, therefore the shell is dark and not transparent.

Dimensions.—Inner shell 0.18 long, 0.12 broad; outer shell 0.24 long, 0.18 broad; ring 0.08 long.

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

3. Perispyris lentellipsis, n. sp. (Pl. 88, fig. 12).

Shell smooth, lentelliptical, with three different isopolar axes, perpendicular one to another. Transverse and sagittal strictures are wanting; but the large enclosed ring and the two pairs of large adjacent annular meshes indicate clearly the position and size of the hidden cephalis. The two other joints (the cupola on the upper and the thorax on the lower pole of the cephalis) are nearly equal, cap-shaped or hemispherical. The outer lentelliptical shell is little larger than the inner, connected with it by numerous thin bristle-shaped radial beams, and exhibits a delicate arachnoidal lattice-work.

Dimensions.—Inner shell 0.15 long, 0.1 broad; outer shell 0.18 long, 0.13 broad; ring 0.08 long.

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

Subfamily 3. Nephrospyrida (vel Paradictyida, Haeckel, 1881).

Definition.—Androspyrida without free basal feet and external constrictions. Shell either spherical or discoidal.

Genus 484. Sphærospyris,^[44] n. gen.

Definition.—Androspyrida with a spherical or subspherical shell, without basal incision and transverse constriction; without free basal feet.

The genus Sphærospyris differs from all other Spyroidea in the regular spherical or spheroidal form of the lattice-shell. It may therefore be easily confounded with some species of the Sphæroidea; but the internal sagittal ring, placed in the median plane of the fenestrated sphere and connected with it by radial beams, leaves no doubt that it is derived from a true Spyroid, either Dictyospyris or Amphispyris, or another genus. Sometimes also four larger collar pores are visible.

1. Sphærospyris sphæra, Haeckel.

Dictyospyris sphæra, Bütschli, 1882, Zeitschr. f. wiss. Zool. vol. xxxvi. pp. 511, 539, Taf. xxxii. fig. 15, a, b.

Shell smooth, nearly spherical, slightly flattened at the base, with small regular circular pores. In the centre of the basal plate a regular rectangular cross with four equal collar pores.

Dimensions.—Diameter of the shell 0.11, of the enclosed ring 0.06.

Habitat.—Fossil in Barbados.

2. Sphærospyris quadriforis, n. sp.

Shell rough, nearly spherical, slightly flattened at the base, with small regular circular pores. In the centre of the basal plate a bilateral symmetrical cross with four ovate collar pores; two cardinal pores twice as large as the two jugular pores and six to eight times as broad as the other shell-pores.

Dimensions.—Diameter of the shell 0.26, of the enclosed ring 0.09.

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

3. Sphærospyris globosa, n. sp. (Pl. 83, fig. 4).

Shell smooth, perfectly spherical, with small subregular circular pores. In the centre of the basal plate no larger collar pores. (The original collar pores are here of the same size as the other pores, and cannot therefore be distinguished.)

Dimensions.—Diameter of the shell 0.13, of the enclosed ring 0.06.

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

Genus 485. Nephrospyris,^[45] Haeckel, 1881, Prodromus, p. 444.

Definition.—Androspyrida with a discoidal, kidney-shaped, or subcircular shell, with a basal incision; without transverse constriction and free basal feet.

The genus Nephrospyris is one of the most peculiar and most modified of the Spyroidea, of extraordinary size, in this respect surpassing all other genera of this suborder, and differing from them in its flat discoidal form. The diameter of the compressed shell often reaches one half millimetre or more; its perimeter is elliptical or nearly circular, smooth, constantly with a characteristic deep sternal incision or a basal sinus on the basal pole of the main axis. The central sagittal ring is comparatively small. The margin is often inflated like a delicate reticular girdle, and contains a large number of peculiar spherical or roundish nucleated cells (Pl. 90, figs. 6-10). According to the observations of Dr. John Murray, made on living Nephrospyris, they are Vorticellina, perhaps constant Symbiontes.

Subgenus 1. Nephrodictyum, Haeckel, 1881, Prodromus, p. 444.

Definition.—Network of the shell simple, with bars of nearly equal breadth.

1. Nephrospyris renilla, n. sp. (Pl. 90, figs. 9, 10).

Shell kidney-shaped, one and a half times as broad as long, and three times as long as the deep kidney-shaped sternal incision. Ring with six pairs of branched apophyses, the bars of the apical pair vertical, of the basal pair divergent. The corresponding bars of the two middle pairs (on the frontal and the occipital face) form together on each side a large pentagonal or hexagonal naso-orbital area, which is surrounded by four or five large polygonal meshes; the other meshes become smaller towards the inflated margin. All meshes simple, without arachnoidal framework.

Dimensions.—Shell 0.3 to 0.4 long, 0.4 to 0.5 broad; ring 0.08 to 0.1 long.

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

2. Nephrospyris nephridium, n. sp.

Shell kidney-shaped, one and two-third times as broad as long, very similar to the preceding species (or only a variety of it?). Ring with seven pairs of branched apophyses. The large naso-orbital area is on the dorsal or occipital side simple, on the ventral or facial side divided by an equatorial pair of transverse horizontal branches into two superior orbital, and two inferior nasal holes. Sternal incision ovate. All meshes simple.

Dimensions.—Shell 0.25 to 0.35 long, 0.4 to 0.5 broad; ring .007 to 0.08 long.

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

3. Nephrospyris phaseolus, n. sp.

Shell kidney-shaped, twice as broad as long, very similar to the two preceding species (or only a variety of them?). Ring with eight pairs of branched apophyses. The large naso-orbital area (between the mitral and collar ring) is on the dorsal and on the ventral side divided by two equatorial pairs of horizontal branches into two superior (orbital and occipital), and two inferior (nasal and suboccipital) holes. Sternal incision cordate. All meshes simple.

Dimensions.—Shell 0.25 long, 0.5 broad; ring 0.06 to 0.07 long.

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

4. Nephrospyris cordata, n. sp.

Shell heart-shaped, about as long as broad. Ring with six pairs of branched apophyses (as in Nephrospyris renilla, Pl. 90, fig. 9). No equatorial transverse branches. Sternal incision cordate, deeper than in all other species of the genus, nearly half as long as the shell. All meshes of the network simple.

Dimensions.—Shell 0.32 long, 0.36 broad; ring 0.05 to 0.06 long.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

Subgenus 2. Paradictyum, Haeckel, 1881, Prodromus, p. 444.

Definition.—Network of the shell double; the larger meshes separated by strong bars, and filled up by a very delicate secondary arachnoidal network.

5. Nephrospyris paradictyum, n. sp. (Pl. 90, figs. 1-8).

Paradictyum paradoxum, Haeckel, 1881, Prodromus et Atlas, loc. cit.

Shell nearly circular, ten times as broad as the inflated marginal girdle, and three times as long as the sternal incision. Ring with six pairs of branched apophyses; the bars of the apical pair nearly vertical, of the basal pair divergent; the corresponding and opposite bars of the two middle pairs (on the occipital and on the frontal face) form together a large middle naso-orbital area; above and below this lie six pairs of larger meshes. All larger meshes of the network are filled up by very delicate arachnoidal framework. The inflated and delicately reticulated marginal girdle of this and of the following closely allied species is usually filled up by nucleated roundish cells (fig. 7), which are Vorticellinæ, according to the observations of Dr. John Murray on living specimens.

Dimensions.—Diameter of the shell 0.5 to 0.6, of the marginal girdle 0.05 to 0.07; ring 0.07 to 0.09 long.

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

6. Nephrospyris paradoxa, n. sp.

Shell kidney-shaped, one and one-third times as broad as long, six times as broad as the inflated marginal girdle, and half as long as the sternal incision. Ring with six pairs of apophyses. Above and below the large naso-orbital holes lie ten pairs of larger meshes. All the meshes are filled up by very delicate arachnoidal network.

Dimensions.—Length of the shell 0.4 to 0.5, breadth 0.5 to 0.7; ring 0.06 to 0.08 long.

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

1. Tripospyris = Basket with a tripod; τρίπος, σπυρίς.
2. Triceraspyris = Basket with three horns; τρίκερας, σπυρίς
3. Tristylospyris = Basket with three styles; τρίστυλος, σπυρίς.
4. Cephalospyris = Head-like basket; κεφαλή, σπυρίς.
5. Dipospyris = Basket with two feet; δίπους, σπυρίς.
6. Brachiospyris = Basket with two arms; βραχίων, σπυρίς.
7. Dendrospyris = Basket with arborescent feet; δένδρον, σπυρίς.
8. Dorcadospyris = Basket with two horns, similar to an antelope; δορκάς, σπυρίς.
9. Gamospyris = Basket with two feet grown together; γάμος, σπυρίς.
10. Stephanospyris = Basket with a garland; στέφανος, σπυρίς.
11. Tetraspyris = Basket with four feet; τέτρα, σπυρίς.
12. Tessarospyris = Basket with four feet; τέσσαρα, σπυρίς.
13. Hexaspyris = Basket with six feet; ἑξά, σπυρίς.
14. Liriospyris = Lily-basket; λείριον, σπυρίς.
15. Cantharospyris = Basket with six feet, like a beetle; κάνθαρος, σπυρίς.
16. Clathrospyris = Latticed basket; κλῆθρον, σπυρίς.
17. Aegospyris = Goat-basket; ἀιγοσπυρίς.
18. Pentaspyris = Basket with five feet; πέντα, σπυρίς.
19. Zygospyris = Bilocular basket, with paired halves; ζυγά, σπυρίς.
20. Elaphospyris = Deer-basket; ἔλαφος, σπυρίς.
21. Taurospyris = Bull-basket; ταῦρος, σπυρίς.
22. Therospyris = Basket with four feet, like a beast; θὴρ, σπυρίς.
23. Petalospyris = Leaf-basket; πέταλος, σπυρίς.
24. Anthospyris = Flower-basket; ἄνθος, σπυρίς.
25. Ceratospyris = Horned basket; κέρας, σπυρίς.
26. Gorgospyris = Medusiform basket; γοργώ, σπυρίς.
27. Circospyris = Basket with a ring; κίρκος, σπυρίς.
28. Dictyospyris = Net-basket; δίκτυον, σπυρίς.
29. Tholospyris = Basket with a cupola; θόλος, σπυρίς.
30. Lophospyris = Basket with a crest; λόφος, σπυρίς.
31. Sepalospyris = Basket with leaves; σήπαλον, σπυρίς.
32. Tiarospyris = Basket with a cap; τιάρα, σπυρίς.
33. Pylospyris = Basket with gates; πύλη, σπυρίς.
34. Acrospyris = Basket with an apical spine; ἄκρα, σπυρίς.
35. Phormospyris = Wicker-basket; φορμός, σπυρίς.
36. Patagospyris = Basket with a patagium; πάταγεῖον, σπυρίς.
37. Rhodospyris = Rose-basket; ῥόδον, σπυρίς.
38. Desmospyris = Basket with a band or string; δεσμός, σπυρίς.
39. Androspyris = Man-like wicker basket; ἀνήρ, σπυρίς.
40. Lamprospyris = Splendid wicker-basket; λαμπρός, σπυρίς.
41. Amphispyris = Basket with a cap on both sides; ἀμφί, σπυρίς.
42. Tricolospyris = Wicker-basket with three joints; τρικῶλος, σπυρίς.
43. Perispyris = Wicker-basket surrounded by an envelope; περί, σπυρίς.
44. Sphærospyris = Spherical wicker-basket; σφαῖρα, σπυρίς.
45. Nephrospyris = Kidney-shaped basket; νεφρός, σπυρίς.