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Show 5G0 ON NEW SHELLS FROM LAKE TANGANYIKA. coloration. Outer lip somewhat expanded, much thickened within, white, concave above, arcuate at the side. Base also thickened and, together with the lower extremity of the whorl, forming a broad, retroverted, and very short cauda. Upper end of labrum joined to the base by a rather thick defined callosity, which spreads over the body-whorl within the mouth. Length 35 millim., diam. above the aperture 16; aperture 15 long, 9 broad. Operculum black, closing the aperture, but at some distance from the peristome. PARAMELANIA CRASSIGRANULATA. Shell solid (? fossil), imperforate, ovate turreted, dirty whitish (? bleached). Whorls probably about 8 ; four remaining narrowly excavated at the upper part, convexish at the sides, strongly plicate and spirally sulcated and ridged. Plicae arcuate, oblique, 12 to 15 on the penultimate whorl, 15 to 1/ on the last, becoming more or less obsolete towards the base. Sulci deep, cutting the plicae into nodules, which number 5 or 6 upon the upper whorls. Transverse ridges on the last further apart below than above the middle, with the exception of 3 or 4 at the extreme base ; these are finer, closer together, and hardly if at all granulous. Aperture, peristome, and basal prolongation very similar to those of the preceding species. Length 28 millim., diam. 13; aperture 13 long, 7 wide. Fig. 2. Paramelania crassigranulata. This species, of which we know hut two specimens in worn and semifossil condition, is distinguished from the preceding by the narrower excavation or tabulation at the upper part of the volutions, and the more rounded and more coarsely granulated ribs and spiral lirae. The general form and the relative proportion of the spire to the length of the last whorl are so much alike in the two forms, that I feel a little hesitation in specifically separating them, bearing in mind the excessive variability of P. nassa. |