Shell smooth, broadly pyramidal. Cephalis ovate, small, blunt, hyaline, with very few and small pores (in the figure of Ehrenberg broken off). Thorax broadly pyramidal, with straight lateral outlines, and nine stout and straight radial beams, which are connected by eight to twelve horizontal complete rings. Meshes in the upper half regular, square, in the lower half broad, rectangular (in the tenth transverse row twice as broad as long).
Dimensions.—Cephalis 0.03 long, 0.02 broad; thorax (with ten transverse rings) 0.15 long, 0.15 broad.
Habitat.—Fossil in Barbados.
6. Sethopyramis trapezoides, n. sp.
Shell smooth, broadly pyramidal. Cephalis large, ovate, hyaline, without pores; its collar septum exhibits distinctly the four collar pores (two larger cardinal and two smaller jugular pores). Thorax broad, pyramidal, with slightly concave lateral outlines and nine (sometimes eight or ten) curved ribs, which are connected by eighteen to twenty-four complete transverse rings. The large meshes, so produced, have the form of a parallel trapezoid, and are in the eighth transverse row three times as broad as long. (Differs from Bathropyramis trapezoides, Pl. [54], fig. 3, mainly by the possession of a well developed cephalis).
Dimensions.—Cephalis 0.04 long, 0.03 broad; thorax (with eighteen rings) 0.32 long, 0.24 broad.
Habitat.—South Pacific, Station 285, depth 2375 fathoms.
7. Sethopyramis spinosa, n. sp.
Shell thorny, slender, pyramidal. Cephalis small, subspherical, with few small pores and a straight, vertical, conical horn twice the length. Thorax with nine straight ribs, which are connected by sixteen to twenty complete transverse nine-angled rings. The large meshes so produced are subregular, square. From each nodal point a short conical spine arises. (Differs from the similar Bathropyramis spinosa, Pl. [54], fig. 4, by the development of the cephalis and the simple pointed, unforked spines.)
Dimensions.—Cephalis 0.03 diameter; thorax (with sixteen rings) 0.2 long, 0.12 broad.