Shell rough, subcylindrical, with three annular septa. The fourth cylindrical joint is four times as long as the second and the third joints. These three joints are nearly equal in breadth. Pores small and numerous, almost square, in regular, transverse rows; two to three in the first joint, five to six in the second and in the third, fourteen to sixteen in the fourth joint. Cephalis flat, cap-shaped, with a short, pyramidal horn. Peristome half as broad as the shell, hyaline, with a coronal of numerous, very delicate, vertical feet.
Dimensions.—Length of the shell (with four joints) 0.2, breadth, 0.08. Length of the single joints, a 0.02, b 0.03, c 0.03, d 0.12.
Habitat.—Central Pacific, Station 271, depth 2425 fathoms.
7. Cyrtophormis corona, n. sp. (Pl. [77], fig. 15).
Shell smooth, conical, ovate, with three deep strictures, about twice as long as broad. The fourth joint is the broadest, inflated, and three times as long as the second and the third joints. Pores small and numerous, circular, in regular, transverse rows; two in the first joint, four in the second and third, and ten in the fourth joint. Cephalis hemispherical, with a stout, pyramidal horn. Peristome two-thirds as broad as the fourth joint, with twelve to fifteen triangular, convergent teeth.
Dimensions.—Length of the shell (with four joints) 0.16, breadth 0.08. Length of the single joints, a 0.01, b 0.03, c 0.03, d 0.09.
Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.
8. Cyrtophormis cornuta, n. sp. (Pl. [77], fig. 18).
Shell thorny, spindle-shaped, with three distinct strictures. Length of the four joints = 2 : 4 : 3 : 5. The third joint is the broadest. Pores circular, of different sizes, in the three first joints double-contoured. Cephalis subspherical, with a large, conical horn of three times the length. The fourth joint is inversely conical, three times as broad as the constricted mouth. Peristome with a coronal of numerous (ten to twenty) irregular, thin, partly forked teeth.
Dimensions.—Length of the shell (with four joints) 0.14, breadth 0.07. Length of the single joints, a 0.02, b 0.04, c 0.03, d 0.05.