the majority, however, of Cyrtoidea, the capsule develops on its basal face a number of depending lobes, as were also found in some Spyroidea (and probably also Botryodea). In this respect we may distinguish two main forms of the capsule in the Cyrtellaria, viz., the primary simple, not lobate form, and the secondary lobate form. The central capsule is originally always enclosed in the cephalis, and has there a simple, subspherical, ellipsoidal or ovate form. As soon as their growth increases, and the enclosing cephalis becomes too narrow, it sends out prolongations in the form of basal lobes, which depend from its base, and proceed through the pores of the basal lattice of the cephalis, or the cortinar pores. In the great majority of Cyrtoidea in which the capsule was observed, either three or four such lobes were seen (already described by J. Müller). Of course this number depends upon the number of cortinar pores, which is either three or four; therefore in the Cyrtoidea with three pores in the cortinar plate, we find three lobes of the central capsule (an odd posterior and two paired anterior); in the Cyrtoidea, however, with four pores in the cortinar plate (the majority) we find four lobes of the central capsule (two smaller anterior jugular and two larger posterior cardinal lobes). Usually each lobe is ovate or pear-shaped and encloses a large oil-globule, and often also an apophysis of the cell-nucleus.
Section I. MONOCYRTIDA, Haeckel, 1862, Monogr. d. Radiol., pp. 280, 281.
Definition.—Cyrtoidea monothalamia, with simple, not jointed shell (or cephalis), without transverse constrictions.
Synopsis of the three Families and six Subfamilies of Monocyrtida.
| Family LIX. Tripocalpida.
Three radial apophyses. |
Mouth open, | 1. Archipilida. | |
| Mouth closed, | 2. Archiperida. | ||
| Family LX. Phænocalpida.
Numerous radial apophyses. |
Mouth open, | 3. Archiphormida. | |
| Mouth closed, | 4. Archiphænida. | ||
| Family LXI. Cyrtocalpida.
No radial apophyses. |
Mouth open, | 5. Archicorida. | |
| Mouth closed, | 6. Archicapsida. |
Family LIX. Tripocalpida, n. fam.
Archipilida et Archiperida, Haeckel, 1881, Prodromus, pp. 427, 429.
Definition.—Monocyrtida triradiata. (Cyrtoidea with a simple, not jointed shell, representing a simple cephalis, with three radial apophyses.)
