Shell campanulate, rough, about as long as broad. Pores subregular, circular, larger in the middle zone, twice to three times as broad as the bars. Mouth constricted, half as broad as the shell. Apical horn straight and stout, three-sided pyramidal, about as long as the shell. Three feet divergent, slightly S-shaped, curved, somewhat longer the the shell.
Dimensions.—Shell 0.1 diameter, horn 0.09 long, feet 0.13 long.
Habitat.—Central Pacific, Station 272, depth 2600 fathoms.
2. Tripilidium hemisphæricum, n. sp.
Shell hemispherical, smooth, nearly twice as broad as long. Pores large, with thin bars, irregular, roundish, of very different sizes. Mouth wide open. Apical horn conical, half as long as the shell. Three feet slender cylindrical, widely divergent, curved, nearly twice as long as the shell.
Dimensions.—Shell 0.08 long, 0.14 broad; horn 0.05 long, feet 0.15 long.
Habitat.—South Pacific, Station 298, depth 2225 fathoms.
3. Tripilidium lychnocanium, n. sp.
Shell hemispherical, thorny, one and a half times as broad as long. Pores regular, circular, hexagonally framed, as broad as the bars. Mouth slightly constricted. Apical horn stout and short, three-sided pyramidal. Three feet cylindrical, straight, divergent, twice to three times as long as the shell. (Similar to Lychnocanium favosum, Pl. [61], fig. 6, perhaps derived from it by reduction of the cephalis.)
Dimensions.—Shell 0.08 long, 0.12 broad; horn 0.02 long, feet 0.2 long.