2. Tripterocalpis conoptera, n. sp. (Pl. [51], fig. 2).
Shell ovate, nearly as broad as long. Pores regular, circular, quincuncial, twice as broad as the bars. In the middle of the shell there arise three conical, smooth, divergent wings, about half as long as the shell. Peristome with six short triangular, oblique, convergent feet.
Dimensions.—Shell 0.16 long, 0.14 broad; wings 0.09 long; feet 0.02 long.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
3. Tripterocalpis ogmoptera, n. sp. (Pl. [51], figs. 3-5).
Shell ovate, nearly as broad as long. Pores small and numerous, circular or roundish, partly confluent, double-contoured (fig. 4). In the middle of the shell there arise three very large conical divergent wings, which are longitudinally striped and longer than half the shell. Peristome with nine short triangular, oblique, convergent feet.
Dimensions.—Shell 0.18 long, 0.16 broad; wings 0.12 long, feet 0.02 long.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
Genus 499. Trissopilium,[[116]] Haeckel, 1881, Prodromus, p. 427.
Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs or wings. Mouth smooth, without terminal feet. Apex with a horn.