Dimensions.—Shell 0.07 long, 0.1 broad; horn 0.06 long, feet 0.14 long.
Habitat.—Indian Ocean, Cocos Islands (Rabbe), surface.
Genus 497. Tripodonium,[[114]] Haeckel, 1881, Prodromus, p. 428.
Definition.—Archipilida (vel Monocyrtida triradiata aperta) with three lateral ribs prolonged into three terminal feet. Apex without horn.
The genus Tripodonium differs from the preceding Tripocalpis, its probable ancestral form, only in the loss of the apical horn (already very small in some forms of the latter). It bears therefore to the latter the same relation that Sethopilium does to Dictyophimus.
1. Tripodonium campanulatum, n. sp.
Shell campanulate, somewhat broader than high, with regular circular pores, twice as broad as the bars. Three broad lateral wings, lamellar, triangular, are prolonged over the peristome into three short triangular lamellar feet one-fourth as long as the shell.
Dimensions.—Shell 0.08 long, 0.09 broad; feet 0.02 long.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
2. Tripodonium ovatum, n. sp.