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Show 1882.] MOLLUSCAN FAUNA OF MADAGASCAR. 3/7 The peristome is very similar ; and the sculpture is somewhat same character. Still there are differences of form, of colour, in the sutures, and in the size of the aperture, which readily distinguish these forms, which no doubt inhabit different districts of the island. Var. a. Shell with a less elevated spire, shorter and broader whorls, more widely umbilicated, with a larger and more oblique mouth, and the outer lip not stained with rose. Greatest diam. 30 millim., height 24. Hab. Betsileo (Cowan). Var. b (Plate XXI. fig. 3). Shell a trifle more ventricose than var. a, with the umbilicus similar to that of the type, but the aperture larger and the peristome white, with the body-whorl smoother, with fewer and subobsolete spiral lirse, except within and around the umbilicus. Greatest diam. 30 millim., height 26|. Hab. Betsileo (Cowan). CYCLOSTOMA CONGENER, sp. nov. (Plate XXI. fig. 1.) Shell openly umbilicated, subdepressedly turbinate, rather smooth, obsoletely spirally sulcate, striated with lines of growth which are puckered and distinct at the sutures; bright yellow, longitudinally streaked with a darker tint, dark cinereous behind the white expanded lip, encircled at the periphery by a vivid purple-brown band and with two or three hair-like lines of a paler colour, both above and below the middle. Spire elevated, conical, ending in a bluish obtuse tip. Whorls 5|, very convex; the last large, strongly lirate around and within the umbilicus, where it is stained with purple-brown. Aperture large, oblique, ovate-subcircular, light brown within except near the lip, where it becomes of a very dark chestnut-brown or nearly black, this colour extending along the inside of the columellar edge. External band and lines visible within. Peristome roundly expanded and reflexed, white, broad on the dextral margin, narrower on the columellar side. Greatest diam. 34 millim., height 30. Hab. Tanala province (Cowan). This form approaches most closely to C. consanguineum of Sowerby (= C. obsoletum of Reeve, not of Lamarck), but may be distinguished by its greater size, its yellow colour, dark apex, and rather more elevated spire. Both species have the same disposition of the spiral bands and lines-namely a single central broad zone, two narrower ones between it and the suture, which are visible on the spire, and two others beneath it and around the lower surface of the whorl. In some specimens of C. consanguineum some of the sulci around the umbilicus are also of a dark colour. On holding up a specimen of C. congener to the light, three lines above and three below the broad band are generally observable. C. obsoletum of Lamarck, according to Delessert's figure (Recueil, pl. 29. f. 1 la) |