Shell nearly cylindrical, smooth. Length of the three joints = 2 : 2 : 8, breadth = 2 : 3 : 3. Cephalis subspherical, with four larger pores. Thorax and abdomen cylindrical, of about equal breadth, with equal, very small pores, disposed regularly in transverse rows, two rows in the thorax, eight to ten in the abdomen. Mouth wide open, a little constricted.
Dimensions.—Length of the three joints, a 0.02, b 0.02, c 0.08; breadth, a 0.02, b 0.03, c 0.03.
Habitat.—Tropical Pacific (Philippine Sea), Station 206, depth 2100 fathoms.
3. Tricolocampe polyzona, n. sp. (Pl. [66], fig. 19).
Shell nearly cylindrical, thick-walled. Length of the three joints = 4 : 4 : 12, breadth = 8 : 9 : 9. Cephalis obtuse, conical. Thorax barrel-shaped. Abdomen in the middle part a little constricted. Pores very numerous, subregular, disposed regularly in transverse rows, six to eight in the cephalis, eight to ten in the thorax, twelve to fifteen in the abdomen. Mouth rather constricted, only half as broad as the abdomen.
Dimensions.—Length of the three joints, a 0.04, b 0.04, c 0.12; breadth, a 0.08, b 0.09, c 0.09.
Habitat.—Central Pacific, Stations 266 to 272, depth 2425 to 2925 fathoms; also fossil in the Nicobars and in Barbados.
4. Tricolocampe stenozona, n. sp. (Pl. [66], fig. 20).
Shell nearly cylindrical, thin-walled. Length of the three joints = 5 : 4 : 9, breadth = 6 : 8 : 9. Form of the three joints and disposition of their pores nearly equal to the preceding species; but the proportion of the joints is different, the shell more delicate, and the mouth more widely open, and nearly as broad as the abdomen.
Dimensions.—Length of the three joints, a 0.05, b 0.04, c 0.09; breadth, a 0.06, b 0.08, c 0.09.