The Atoll of Funafuti, Ellice group : its zoology, botany, ethnology and general structure based on collections made by Charles Hedley of the Australian Museum, Sydney, N.S.W.
Cerithium oceanicum, sp. nov. — (Fig. 19)
Cerithium oceanicum, sp. nov.
Shell rather elongate, almost truncate anteriorly. Colour uniform chocolate. Whorls eight, the upper biangulate, the last equal in length to the remainder. Sculpture: there are on the penultimate whorl (including varices) twenty low, rounded, longitudinal ribs, which crenulate the suture. These cross regularly from whorl to whorl, becoming fewer but proportionately stronger as they ascend the spire; on the last whorl they become evanescent. Two spiral lines of granules descend the spire, appearing on the crest of each rib as a smooth boss. On the body whorl there are besides, beneath these, three spiral lines in which the beads have nearly fused into a smooth continuous ridge, the uppermost of these is sometimes apparent in the spire as a super sutural fasciole. The whole surface of the shell except the beads, is covered by close, microscopic, raised spiral hair lines. Three, obliquely ascending, continuous lines of varices mount the spire a third of a whorl apart. Aperture slightly oblique, semi-lunate; anterior canal hardly more than a notch, Fig. 19. directed sideways; columella anteriorly truncated, externally wrinkled and curved downwards and outwards, internally with a low ridge-tubercle, callus on body whorl medium; outer lip strongly variced behind, edge sharp, notched by the major spiral sculpture, finely grooved within. Length 8, breadth 4 mm.
A single, perhaps not quite adult specimen from the lagoon beach.
This shell seems to be a dwarf of the species which Sowerby has figured* as "Cerithium granosus, Kiener." The shell which Kiener himself figures† so differs in contour, sculpture, size, page 432colour and details of the aperture, that Sowerby's determination can only be considered aa one of the blunders which so, plentifully occur in his works.
* Sowerby—Thesaurus Conch, if, 1855, pl. clxxxi., fig. 123, 124.
† Kiener—Coquilles Vivantes, Canaliferes i. (n.d.), pl. iv., fig. 5, p. 57.