Shell subcylindrical, with longitudinal ribs, and five to eight transverse strictures, and prominent girdles between them. On each girdle (at the lowermost edge of each joint) a single transverse row of circular pores. The three or four uppermost joints are united, and represent a conical cephalis.
Dimensions.—Length of the shell (with six joints) 0.1; length of each joint 0.01 to 0.15, breadth 0.04 to 0.06.
Habitat.—Central Pacific, Station 263 to 274, depth 2350 to 2925 fathoms.
5. Lithomitra eruca, n. sp. (Pl. [79], fig. 3).
Shell subcylindrical, diminishing slightly towards both ends, with ten to fifteen slight strictures. On each joint a single transverse row of circular pores, descending obliquely in the wall. The two or three first joints form together a roundish cephalis. Usually each joint is three times as broad as long.
Dimensions.—Length of the shell (with twelve joints) 0.2; length of each joint (on an average) 0.016, breadth 0.05.
Habitat.—Central Pacific, Station 265 to 268, depth 2700 to 2900 fathoms; fossil in Barbados.
6. Lithomitra chrysalis, n. sp. (Pl. [79], fig. 4).
Shell subcylindrical, diminishing slightly towards both ends, with elegant longitudinal ribs, and with five to eight slight strictures. Each of the upper joints with two (or sometimes three) transverse rows of small pores; each of the lower joints with only a single row.
Dimensions.—Length of the shell (with six joints) 0.11; length of each joint 0.01 to 0.015, breadth 0.04 to 0.05.