21. Sethoconus facetus, n. sp. (Pl. 55, fig. 1).
Cephalis small, hemispherical, with distinct collar septum, the same network as the thorax, and numerous bristle-shaped horns of the same length. Thorax wide, conical, about as long as broad, with slightly convex outlines; its network extremity delicate, with very small and numerous, regular, hexagonal pores, disposed in numerous divergent, longitudinal series, which are convoluted somewhat spirally around the shell axis. Surface covered with thin, scattered, bristle-shaped spines, about as long as the cephalis.
Dimensions.—Cephalis 0.02 diameter, thorax 0.2 long, 0.22 broad.
Habitat.—Central Pacific, Stations 271 to 274, surface.
22. Sethoconus anthocyrtis, n. sp. (Pl. 62, fig. 21).
Cephalis small, subspherical, with very small pores and numerous radial, bristle-shaped spines of the same length. Thorax wide, conical, about as long as broad, with parabolic outlines, its network very delicate, with subregular, hexagonal meshes. Surface with scarce, bristle-shaped spines (not represented in the figure). Mouth with a corona of numerous small, vertical spines.
Dimensions.—Cephalis 0.025 diameter, thorax 0.26 long, 0.24 broad.
Habitat.—North Pacific, Station 248, surface.
23. Sethoconus virgultus, n. sp.
Cephalis and thorax nearly of the same form and stricture as in Sethoconus facetus, but larger and wider, with the same delicate, hexagonal network (Pl. 55, fig. 1); it differs from the latter by the wider, more convex and campanulate form, but mainly by the armature of the surface, which is densely covered with thin, arborescent, bristle-shaped spines, irregularly branched, and four to eight times as large as the cephalis.
Dimensions.—Cephalis 0.02 diameter, thorax 0.32 long, 0.4 broad.
Habitat.—South Pacific, Station 288, surface.
24. Sethoconus setosus, n. sp.
Cephalis small, subspherical, with distinct collar septum, and the same network as the thorax, with numerous bristle-shaped horns of the same length. Thorax slenderly conical, twice as long as broad, with irregular, polygonal pores of little different sizes, and very thin bars. Surface covered with perpendicular, simple, bristle-shaped spines, about as long as the cephalis.
Dimensions.—Cephalis 0.02 diameter, thorax 0.12 long, 0.22 broad.
Habitat.—Central Pacific, Stations 266 to 272, surface.
