Habitat.—Central Pacific, Station 274, depth 2750 fathoms.
Subgenus 2. Arachnopilium, Haeckel, 1881, Prodromus, p. 435.
Definition.—Thorax with three large lateral holes between the three latticed wings.
4. Pteropilium clathrocanium, n. sp. (Pl. [64], fig. 7).
Arachnopilium clathrocanium, Haeckel, Prodromus, 1881, p. 435.
Shell very delicate, with two deep strictures. Length of the three joints = 2 : 4 : 2, breadth = 2 : 10 : 5. Cephalis subspherical, with circular, polygonally-framed pores, and a central, three-sided pyramidal, apical horn of twice the length. Thorax three-sided pyramidal, with three large, ovate holes between three prominent latticed wings. From its surface arises a very delicate, arachnoidal network with irregular, polygonal meshes, enveloping also the entire cephalis. Abdomen wide and short, as long as the cephalis, and half as broad as the distance of the wings, twice as broad as the constricted mouth.
Dimensions.—Length of the three joints, a 0.04, b 0.08, c 0.04; breadth, a 0.05, b 0.2, c 0.1.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
Genus 587. Theopodium,[[204]] Haeckel, 1881, Prodromus, p. 435.
Definition.—Theopilida (vel Tricyrtida triradiata aperta) with three divergent solid ribs, which lie in the wall of the thorax and the abdomen, and are prolonged into three solid terminal feet.