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Show 740 ON SHELLS FROM PERAK AND NICOBAR ISLANDS. [Dec. 2, ultimo maximo, rotundato, basi vix convexo; apertura superne contracta, inferne late dilatata, margine columellari callose retrorsum paululum deflexo, margine externo convexe rotundato. Long. 2\ (vix), diam. 1 \ mill. Another shell found in the same locality by Dr. Townsend. The sculpture and characters of the aperture are admirably represented by the figure ; the last whorl but one, however, should be considerably more convex and consequently less turreted and less conspicuous; the base of the last whorl is a shade too convex, giving the shell an umbilicate appearance, which it does not possess (G. N.). GEORISSA SEMISCULPTA, n. sp. (Plate LIX. figs. 3, 3 a.) Testa parva, solida, viridescens, imperforata ; anfractu ante-penultimo valide sulcato, sulcis concentricis atque approximatis, ultimo subcompresso, basi planiusculo, superne concentrice valideque sulcato, inferne leevi; apertura superne perangusta, inferne late dilatata, margine columellari incrassato, abrupte retrorsum deflexo ac callositate validissima regionem umbilicalem tegente instructo, margine externo inferne subangulato. Diam. (ult. anfract.) 2 mill.; alt. apert. 0*05 inch. A single mature specimen, with the spire unfortunately broken, was found by Dr. Townsend in the Buket Pondong cave in Perak. It differs so conspicuously from every other known species, and would be so easily recognized again, that I have not hesitated to describe it, though I do not usually do so when I possess only a unique specimen. The figure is perfect (G. N.). EXPLANATION OF THE PLATES. PLATE LIX. Fig. 1. la, lb. Microcystina townsendiana, n. sp., x20, p. 736. 2. Ennea perakensis, n. sp., X8, p. 735. 3. 3a Georissa semisculpta, n. sp., X12, p. 740. 4. Acmella moreletiana, n. sp., x24, p. 737. 5. roepstorffiana, n. sp., X 24, p. 737. 6. Georissa monterosatiana, n. sp., xl2, p. 739. 7. Pupisoma ?, young, X 24, p. 736. 8. Clausilia ?, young, X 24, p. 736. PLATE LX. Fig. 1, 1 a, 1 b. Opisthostoma perakensis, n. sp., X24, p. 738. 2, 2a, 2b. pauluccice, x24, p, 738. 3, 3 a. Biplommatina crosscana, n. sp., X24, p. 738. 4, 4 a, 4 b. mirabilis, n. sp., X 24, p. 739. 5, 5 a. Palaina superba, n. sp. x8, p. 739. |