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.
Subgenus 2. Tholospyridium, Haeckel.
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, bearing an irregularly branched horn. Caudal foot short conical, simple. Two pectoral feet half as long as the shell, angular, subvertical, irregularly branched.
Dimensions.—Shell 0.15 diameter, ring 0.1 long, pectoral feet 0.07 long.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
5. Tholospyris cupola, n. sp. (Pl. [89], fig. 4).