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Show 1882.] MOLLUSCAN FAUNA OF MADAGASCAR. d»/ strongly lirated for this genus. It is a smaller form than P. madagascariensis, has a shorter and more obtuse spire, a narrower perforation and spiral striation. P. lirata is more strongly lirate than it, has the spire even still shorter, the body-whorl is prominently shouldered above, and the aperture is longer in proportion. PLANORBIS MADAGASCARIENSIS, sp. nov. (Plate XXII. figs. 20-22.) Shell moderately thick, deeply excavated both above and below, corneous brown, rather strongly striated by the lines of growth, and sometimes exhibiting traces of spiral striation. Whorls 4-4|, rapidly increasing; the last large, rather high, convex, rather deeply incurved at the suture both on the upper and underside, finely malleated, chiefly round the middle. Aperture largish, broadly lunate, raised above or on a level with the penultimate whorl. Peristome thin, receding at the base, its extremities connected by a very thin deposit of callus on the whorl. Greatest diam. 12^ millim., smallest 10, height 4|. Hab. Lake Itasy (Johnson). This species is very like P. pfeifferi, Krauss (Sudafr. Moll. pl. v. f. 7), but may be distinguished by the malleation of the last whorl, its greater height, and browner colour. NERITINA GAGATES, Lamarck. Neritina gagates, Lamarck (vide Martens, Conch. Cab. p. 94). Hab. Tamatave (Cowan). Two specimens from the above locality I believe to belong to this species, differing only in the deep red colour of the columellar callosity, and the olive-green tint of the outer lip. The form is the same; and the denticles on the columella, the painting, the microscopic spiral sculpture, and the operculum are all similar. NERITINA FULGETRUM, Reeve. (Plate XXII. figs. 23, 24.) Neritina fulgetrum, Reeve, Conch. Icon. pl. 23. f. 103 a, sp. 103. Hab. 1 (Reeve) ; south of Tamatave (Johnson). This species has hitherto been represented by a single specimen without any locality in the Cumingian collection, now in tbe British Museum. As the description in the ' Conchologia Iconica ' is very short and incomplete, I will here add a few further details. The black zigzag lineolation at times is very close, thus giving the shell a greyish appearance when viewed at a distance ; and a character not referred to by Reeve, but indicated in his figure, is the brown margin to the body-whorl at the suture, beneath which the volution is faintly constricted. The columellar callosity is much thickened and of a red colour, and extends some distance over the whorl. The edge of the columella is pale, straight, with a shallow sinus a little below the middle, furnished with about a dozen denticles. The aperture is rather small, bright yellow far within, then whitish, and again yellow or greenish-yellow at the lip. The operculum is slaty black ex- |
