1. 80, pp. 61-64 24 March 1967 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON A NEW LAND SNAIL OF THE FAMILY PROSERPINIDAE FROM CHIAPAS, MEXICO (GASTROPODA: PROSOBRANCHIA ) By Fred G. Thompson Florida State Museum, University of Florida The moUuscan family Proserpinidae is represented in Mexico by only a few species, while members of this family have not yet been recorded from Central America (von Martens, 1890-1901: 44-45; 609; Dall, 1926: 486-487). The new species described below is the first record of the genus Linidiella Jousseaume (1889) north of Venezuela, and is an important addition to the fauna of Mexico because of the species' zoo-geographic relationships. Linidiella sulfureus new species Description: Shell (Figs. 1-3) small. Depressed helicoid. Spire slightly elevated, weakly convex in outline. Shell 0.63-0.68 times as high as wide. Surface smooth, glossy. Light sulfur yellow. Fresh shells weakly transparent with very fine, light sigmoid radial lines that appear to be in shell matrix. 4.7-5.1 whorls. Nuclear whorl 0.7 mm in diameter. Suture distinct, but weakly impressed, covered with thin enamel wash that extends onto preceding whorls. Periphery of last whorl rounded. Dorsal surface of whorls nearly flattened, only weakly arched between sutures. Ventral surface also nearly flattened. Um-bilical area covered with finely granular callus that covers about one-fourth or one-third of the ventral surface. A slight, sparsely granulate deposit extends beyond umbilical callus. Aperture semilunar. Lip simple, but not sharp, weakly recurved at periphery and along base near columella. Lip slightly thickened along baso-colimiellar region. Columella nearly straight; with single low, but strong, spiral lamella located about midway on columella. Measurements of holotype: shell height, 3.3 mm; major diameter, 5.2 mm; minor diameter, 4.3 mm; aperture height, 2.6 mm. Two paratypes are slightly larger than the holotype, but show no noticeable variation in proportions. Measurements for the largest 10— Proc. Biol. Soc. Wash., V^l. 80, 1967 ( 61 )
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