Page:Scientific results HMS Challenger vol 18 part 2.djvu/266

1142 fissure. The apex bears a short and stout, three-sided pyramidal horn, the hollow base of which is closed by a small cortinar septum with three collar pores (fig. 8b). This seems to indicate a rudimentary cephalis and the derivation of this species from Lychnocanium (Pl. 61). Peristome constricted, only one-fourth as broad as the shell, with three short, conical, nearly vertical feet. The central capsule (fig. 8a) in the specimen examined was well preserved, hemispherical, not lobate, and filled up the upper half of the shell-cavity (beyond the rudiment of the cortinar septum).

Dimensions.—Shell 0.2 long, 0.12 broad; horn 0.01 long, feet 0.02 long.

Habitat.—Tropical Atlantic, Station 348, depth 2450 fathoms.

7. Tripilidium elongatum, n. sp.

Shell elongate, smooth, nearly cylindrical, in the upper third conical. Pores small and numerous, regular, circular, half as broad as the bars, disposed in about thirty longitudinal alternating rows. Peristome scarcely constricted. The apical horn and the three parallel feet are of equal size and similar form, straight, conical, one-sixth as long as the shell.

Dimensions.—Shell 0.12 long, 0.06 broad; horn and feet 0.02 long.

Habitat.—Fossil in Barbados.

Definition.—Feet forked or branched.

8. Tripilidium dichopodium, n. sp.

Shell hemispherical, nearly twice as broad as long, smooth. Pores irregular, roundish, twice to four times as broad as the bars. Mouth wide open. Apical horn spindle-shaped, half as long as the shell. Three feet cylindrical, nearly straight and parallel, as long as the shell, forked at the distal end. (Exhibits an external similarity to Tripospyris semantis, Pl. 84, fig. 2, but has no trace of sagittal ring and constriction, and the simple shell-cavity has a wide open mouth.)

Dimensions.—0.06 long, 0.1 broad; horn 0.03 long, feet 0.07 long.

Habitat.—North Pacific, Station 241, depth 2300 fathoms.

9. Tripilidium cladopodium, n. sp.

Shell campanulate, rough, about as long as broad. Pores subregular, circular, as broad as the bars. Mouth slightly constricted. Apical horn and three divergent feet of nearly equal size and form, three-sided prismatic, straight and stout, irregularly dentate and branched, somewhat longer than the shell.

Dimensions.—Shell 0.08 diameter; horn and feet 0.1 to 0.12 long.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.