Page:Scientific results HMS Challenger vol 18 part 2.djvu/203

Rh 1. Tholospyris tripodiscus, n. sp. (Pl. 89, fig. 1).

Shell campanulate, smooth, as broad as long, with deep sagittal stricture. Cephalis compressed, with irregular roundish pores; two or three pairs of larger annular pores on each side of the ring. Basal plate with four large pores. Galea with two very large opposite holes (an occipital and a frontal opening). A slender free perpendicular columella connects the uppermost part of the sagittal ring with the strong three-sided pyramidal apical horn. All three feet of equal length, half as long as the ring, three-sided, prismatic, divergent, with three dentated edges.

Dimensions.—Shell 0.13 diameter, ring 0.08 long, feet 0.05 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Tholospyris fenestrata, n. sp. (Pl. 89, fig. 2).

Shell roundish polyhedral, smooth, with slight sagittal stricture. Cephalis nearly cubical, with irregularly roundish pores; two or three pairs of larger pores on each side of the ring. Basal plate with two very large pores. Galea pyramidal, with two large occipital holes. Columella enclosed in the dorsal wall of the galea, prolonged into an oblique pyramidal spine of the same length. Two pectoral feet pyramidal, nearly vertical and as long as the ring, twice as long as the caudal foot.

Dimensions.—Shell 0.12 diameter, ring 0.07, pectoral feet 0.05 long.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

3. Tholospyris galeata, n. sp.

Shell helmet-shaped, thorny, with deep sagittal stricture. Cephalis campanulate, with subregular circular pores. Basal plate with three large pores. Galea hemispherical, separated from the cephalis by a sharp horizontal stricture; pores smaller. A slender free columella connects the apex of the ring with the strong conical apical horn, which is half as long as the ring. All three feet of equal length, divergent conical, as long as the horn.

Dimensions.—Shell 0.14 diameter, ring 0.09 long, feet 0.08 long.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

Definition.—Basal feet forked or branched.

4. Tholospyris ramosa, n. sp. (Pl. 89, fig. 3).

Shell helmet-shaped, smooth, with deep sagittal stricture. Cephalis nearly spherical, with irregularly polygonal pores; four or five pairs of larger annular pores on each side of the strong angular ring. Cupola flat, conical, with two pairs of larger pores. Columella enclosed in its dorsal wall,