Dimensions.—Cephalis 0.02 diameter; thorax 0.5 long, 0.3 broad.
Habitat.—South Atlantic, Station 335, depth 1425 fathoms.
Genus 562. Spongopyramis,[[179]] n. sp.
Definition.—Sethophormida (vel Dicyrtida multiradiata aperta) with numerous straight or slightly curved radial ribs in the wall of the pyramidal thorax. Network spongy. Cephalis commonly without horn.
The genus Spongopyramis has arisen from Sethopyramis by development of an irregular spongy framework around the lattice-shell, and is one of the small number of Cyrtoidea in which the shell-wall exhibits a spongy structure. In both observed species the cephalis is small, but evident.
1. Spongopyramis spongiosa, n. sp. (Pl. [56], fig. 10).
Plectopyramis spongiosa, Haeckel, 1881, Prodromus et Atlas, loc. cit.
Shell partly or entirely enveloped by spongy framework, slender, pyramidal, with rather straight outlines. Cephalis very small, ovate, hyaline. Thorax with nine very stout and nearly straight ribs, which are connected by fifteen to twenty or more irregular, interrupted transverse bars. The irregular quadrangular meshes so produced are filled up by an irregular secondary network, with meshes of very different size and form. The dense spongy envelope, which in the specimen figured covered only half the shell, was complete in another older specimen.
Dimensions.—Cephalis 0.015 long, 0.01 broad; thorax 0.4 long, 0.25 broad.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.