OCR Text |
Show 1879.] SHELLS FROM PERAK AND THE NICOBAR ISLANDS. 737 ACMELLA MORELETIANA, Nevill (Handl. Moll. Ind. Mus. 1878 p. 251, Batti Malve). (Plate LIX. fig. 4.) Testa minima, subaperte umbilicata, conico-turrita, hyalina, polita atque nitida ; circa regionem umbilicalem confertim plicata, plicis validis, regulariter incisis, prope suturam " lente"] minutissime striatula, striis scepe haud videndis; anfract. 5§, convexiusculi, gradati, sutura excavata sejuncti, ultimo globuloso, inferne convexo ; apertura perfecte rotundata, marginibus approximatis, sed haud continuis; peristomate paululum incrassato, margine columellari sensim rotundato, umbilicum haud tegente. Long. 2, diam. l\ mil. (G.N.) The late Dr. Stoliczka found this species in abundance on the little island of Batti Malve, twenty miles south of Car Nicobar. The regular distinct plications of the central portion of the base, which crowd the interior of the umbilicus, are a peculiar characteristic; in some of the scarcely mature specimens, under a strong lens, I can just detect near the suture, here and there, traces of a most minute striation ; otherwise the shell is of a perfectly smooth, polished, and translucent texture ; the whorls are more convex than those of A. roepstorffiana, the aperture higher in proportion to its breadth, with the columellar margin not bent abruptly back over the umbilicus, but evenly and gently rounded. Colonel Austen's figures of both these species are * excellent, scarcely to be surpassed. The only possible criticism is that the margins of the aperture of this species, in especial, may to some appear continuous, which is not the case (G. N.). ACMELLA ROEPSTORFFIANA, Nevill (Handl. Moll. Ind. Mus. 1878, p. 25, Katchall, Nicobar Islands). (Plate LIX. fig. 5.) Testa minima, peranguste umbilicata, conico-turrita, nitida, sericina, omnino distincte, subconfertim et regulariter striata, striis acute filifor mibus, obliquis, ad basin flexuosis, regionem umbilicalem paululum magis conspicuis; anfract. 5, gradati, vix convexiusculi, sutura excavata sejuncti, ultimo ad peripheriam paululum compresso; apertura minima, subcircularis, peristomate incrassato, haud continuo, subobsolete duplici, margine externo perconvexo, margine columellari valide retrorsum arcuato plus minusve umbilicum tegente. Long. 1%, diam. 1 mill. (G. N.) This small species, a few specimens only of which were found by the late Dr. Stoliczka at Katchall, one of the Nicobar Islands, is distinguished from all the other described species of the genus by its being throughout regularly, rather strongly striated, the striae being acute and " thread-like ; " the shell is of a silky, translucent and shinin°* texture, with 5 almost cylindrically turreted whorls, the last a trifle compressed at the periphery ; the umbilicus is exceedingly narrow and partially overlapped by the thickened peristome, which here and there, under the lens, clearly shows a duplex character ; the aperture is very small, unusually broad in proportion to |