Page:Scientific results HMS Challenger vol 18 part 2.djvu/153

Rh 13. Tripospyris semantidium, n. sp.

Shell nut-shaped, thorny, with sharp sagittal stricture and subcircular ring. Basal plate with three pairs of large pores. Facial and occipital plates each with three pairs of large squarish pores. Lateral pores small and numerous, irregular roundish. Apical horn half as long as the shell and the three feet; all four spines straight, cylindrical, with thickened club-shaped end.

Dimensions.—Shell 0.12 long, 0.13 broad; horn 0.06 long, feet 0.15.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

14. Tripospyris eucolpos, n. sp. (Pl. 84, fig. 4).

Shell thorax-shaped, smooth, with two vaulted bosoms, separated by a deep sagittal stricture and an internal primary ring. Basal plate constricted, with three pairs of collar pores. The other lattice-work with subregular circular pores. Apical horn and the three feet shorter than the shell, straight, divergent; their inner half thinner, cylindrical, smooth, their outer half an ovate dimpled cone.

Dimensions.—Shell 0.1 long, 0.13 broad; horn and feet 0.06 long.

Habitat.—Indian Ocean, Cocos Islands (Rabbe), surface.

15. Tripospyris tribrachiata, Haeckel.

Cladospyris tribrachiata, Ehrenberg, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 68, Taf. xxi. fig. 8.

Shell subspherical, smooth, with slight sagittal stricture and numerous, very small circular pores. Basal plate with numerous small pores. Apical horn and the three divergent feet very large and stout, straight, three-sided prismatic, with dentate edges, two to three times as long as the shell.

Dimensions.—Shell diameter 0.05; horn and feet 0.1 to 0.15 long.

Habitat.—Fossil in Barbados.

16. Tripospyris furcata, n. sp. (Pl. 83, fig. 11).

Shell nut-shaped, smooth, with deep sagittal stricture and broad ring. Basal plate with three pairs of small pores. Facial and occipital plates each with a pair of very large holes. Apical horn and caudal foot simple conical, two pectoral feet forked or irregularly branched.

Dimensions.—Shell 0.08 long, 0.12 broad; horn and feet 0.05 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

Definition.— with three basal feet and three coryphal horns.

The genus Triceraspyris has arisen from the preceding ancestral Tripospyris by the development of two paired frontal horns, so that the shell here bears six appendages,