Shell subspherical, rough, with circular pores of different sizes. Mouth constricted, circular, simple, two-thirds as broad as the shell, with three large divergent feet, which are three-sided prismatic, irregularly branched, and twice as long as the shell.
Dimensions.—Shell 0.07 long, 0.08 broad; feet 0.12 long.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
Genus 503. Tridictyopus,[[120]] Haeckel, 1881, Prodromus, p. 428.
Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three latticed terminal feet. Shell ovate or subconical, with an apical horn.
The genus Tridictyopus differs from the nearly allied Tripilidium in the possession of three large fenestrated shovel-shaped feet, forming direct prolongations of the large conical shell. The lattice work exhibits a peculiar elegant structure recurring in the similar, perhaps nearly related, Cephalospyris (Pl. [83], fig. 10; Pl. [96], fig. 28). The central capsule is large, ellipsoidal or ovate, and fills up the greater part of the shell cavity (compare R. Hertwig, 1879, loc. cit., p. 75).
1. Tridictyopus vatillum, n. sp. (Pl. [51], fig. 8).
Shell campanulate, about as long as broad (excluding horn and feet). Pores irregular, polygonal, in the middle part more regular, triangular. Horn short and stout, three-sided pyramidal. Three feet large, triangular, shovel-shaped, about half as long as the shell.
Dimensions.—Shell 0.14 long, 0.15 broad.
Habitat.—South Atlantic, Station 332, depth 2200 fathoms.