Dimensions.—Length of the shell (with five joints) 0.1; length of the fifth joint 0.04, breadth 0.08.
Habitat.—Indian Ocean, Zanzibar, depth 2200 fathoms (Pullen).
18. Lithostrobus seriatus, n. sp. (Pl. 79, fig. 15).
Shell slender, conical, smooth, with straight axis, and four or five deep strictures. Joints little different in length, increasing towards the inflated last joint, which is twice as long as the preceding. On each joint four or five transverse rows of small circular pores. Horn small, bristle-shaped, oblique. This common species is rather variable.
Dimensions.—Length of the shell (with five joints) 0.14; length of the fifth joint 0.05, breadth 0.06.
Habitat.—Central Pacific, Stations 270 to 274, depth 2350 to 2925 fathoms.
19. Lithostrobus cornutus, n. sp. (Pl. 77, fig. 6).
Shell slender, conical, subcampanulate, smooth, with three or four deep strictures. Joints of different lengths, the third and the fourth twice as long as the second, four times as long as the first. Transverse rows of small circular pores; three in the first joint, five in the second, eight in the third and in the fourth. Horn large, pyramidal, about as long as the third joint.
Dimensions.—Length of the shell (with four joints) 0.12; length of the third joint 0.04, breadth 0.06.
Habitat.—Central Pacific, Station 265 to 268, depth 2700 to 2900 fathoms.
20. Lithostrobus microporus, Bütschli.
Shell slender, conical, smooth, very similar to the preceding species, differs mainly in the more slender form and the smaller pores. The first joint has four, the second eight, the third ten transverse rows of pores. Horn conical, as long as the cephalis. The third joint in this and the preceding species is campanulate, and large.
Dimensions.—Length of the shell (with four joints) 0.11; length of the third joint 0.05, breadth 0.04.
Habitat.—Fossil in Barbados.
21. Lithostrobus quadratus, n. sp.
Shell broad, conical, smooth, with straight axis, and six to eight deep strictures. Joints of different lengths, usually alternately longer and shorter. The seventh joint five times as broad as long, twice as long as the sixth and the fourth; six transverse rows of pores in the seventh, three
