Caecum vertebrale, sp. nov.
(Fig. 15).

Caecum sp., De Folin, Challenger Reports, Zoology, xv., 1886, p. 684, pl. ii., fig. 12.

Shell of moderate size for the genus, white (bleached), rather curved, slightly tapering, ornamented with twenty-five strong, pretty regular rounded, transverse rings, which are separated by interstices of corresponding breadth and depth. Septum a low rounded dome. Length 2·15, breadth ·56 mm.

A single perfect specimen, gathered on the sandy shore of the lagoon, is with some confidence identi-fied with a nameless fragment dredged by the " Challenger " off Honolulu.

Fig. 15.