Cerithium zebrum, Kiener.

Tryon, loc. cit., p. 137, pl. xxv., figs. 71, 72.

I refer to this species a small shell abundant on the lagoon beach, 7 mm. long, variously coloured—brown, cream, mauve and salmon, unbanded and banded. No really satisfactory figure or description of it exists, the earliest is much the best. Melvill and Standen, who recognise it from the Loyalties, erroneously state that it was originally described from the Galapagos, whence Sowerby reported it. The locality given by Kiener himself^* is Mauritius. Tryon adds Samoa. I found it in Port Moresby, British New Guinea and at Oubatche, New Caledonia. It is represented in this Museum from the New Hebrides. So widespread and variable a species probably possesses a synonomy to match. I agree with Langkavel's^† remark that C. ianthinum of Gould, should be here included, which would extend the geographical range of the species to Tahiti and the Paumotus. It is likely that C. unilineatum, Pease and C. dichroum, Melvill and Standen. should be reduced to C. zebrum. Pease adds C. aspersum, Deshayes as a synonym.^‡

Cerithium impendens, sp. nov. (Pig. 23). Shell strong, stout, regularly conical, each of the upper whorls overhanging the next, bi-angled above the suture, heavily variced on the back of the last whorl. Colour — upon a white ground is painted ochre-yellow, in one instance chocolate, which chiefly prevails on the base and between the ribs, thus accentuating the projections to the eye. Whorls eight, suture deeply impressed. Sculpture—peculiar buttress ribs ornament the page 435 spire, the penultimate whorl has ten and those above a proportionate decrease; they are weak at the suture, which they barely sinuate, and gain in breadth and height as they cross the whorl, projecting over the suture beneath them. They do not cross continuously from whorl to whorl, nor do they regularly alternate; they grow evanescent on the last whorl and cease with a stout and heavy varix one-third of the whorl behind the aperture. In this latter space, reminiscences of them occur as tubercles on the angle and at the suture. On the last whorl about twenty fine spiral threads are evenly distributed between the suture and the anterior point of the shell; the uppermost of these ascend the spire and are alike prominent on ribs and interspaces. Aperture perpendicular, subtriangular; columella sharply sinuate, anterior notch not produced into a canal; callus on body whorl slight; outer lip thickened slightly and reflected, angled sharply at the posterior insertion. Length 4½, breadth 2 mm.

Fig. 23.

Seven examples from the lagoon beach. Perhaps this is a member of the subgenus Colina.