The Central Capsule of the Sphærocapsida is spherical, constantly smaller than the enclosing concentric shell, and separated from it by the calymma. Its structure seems to be the same as in the Acanthonida, and specially in the Astrolonchida. The pseudopodia (not yet observed) are probably protruded only through the twenty perspinal holes or the eighty aspinal pores.
Synopsis of the Genera of Sphærocapsida.
| I. Subfamily Astrocapsida.
Radial spines connected with the porous shell, as long or longer than its radius. Eighty aspinal pores. |
Spines as long as the radius, without external prolongation, | 344. Sphærocapsa. | |
| Spines longer than the radius, with external prolongation, | 345. Astrocapsa. | ||
| II. Subfamily Porocapsida.
Radial spines not connected with the porous shell, shorter than its radius. Twenty perspinal pores. |
Perspinal holes of the shell simple, without external prolongation, | 346. Porocapsa. | |
| Perspinal holes of the shell prolonged into radial centrifugal tubuli, | 347. Cannocapsa. | ||
| III. Subfamily Cenocapsida.
Radial spines disappeared. |
Twenty perspinal holes of the shell simple, without tubular prolongation, | 348. Cenocapsa. |
Subfamily 1. Astrocapsida, Haeckel.
Definition.—Radial spines connected with the porous shell, as long as or longer than its radius. Therefore the shell pierced by eighty aspinal pores (four around each spine).
Genus 344. Sphærocapsa,[1] Haeckel, 1881, Prodromus, p. 469.
Definition.—Sphærocapsida with twenty radial spines as long as the radius of the shell, without external prolongation; therefore their distal ends inserted in the perspinal holes, each of which is composed of four aspinal pores.
The genus Sphærocapsa is the most common form of the Sphærocapsida, and comprises those species in which the radial spines are as long as the radius of the shell, and therefore are connected with the margin of its aspinal holes, but not prolonged beyond its surface.
- ↑ Sphærocapsa = Spherical capsule; σφαῖρα, κάψα.
