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Show 388 MR. E. A. SMITH ON THE [Apr. 18, teriorly, with the arcuate margin red, and reddish on the inner surface, with two pale rays from the nucleus, one central and the other sub-marginal, the extreme edge being blackish. In all these respects it coincides with that of N. gagates, Lamarck, from the Mauritius; and the terminal processes are similar in both forms. Von Martens s conjecture that the species might belong to N. retifera, Benson (Conch. Cab. p. 283), is not to be wondered at, considering the briefness of Reeve's description, and the fact of only the back of the shell being figured. B. CONCHIFERA. CORBICULA MADAGASCARIENSIS, sp. nov. (Plate XXII. figs. 25-27.) Shell a little inequilateral, rounded and narrow in front, much broader, squarish, and sub truncate posteriorly, arcuate along the ventral margin, finely concentrically striated : yellowish, greenish down the posterior side. Umbones a little prominent, incurved, situated a little anteriorly. Interior lilac, with two or three rather distant concentric purple zones, stained with dark purple down the posterior side, and with a smaller stain of the same colour at the anterior side. Length 11| millim., width 14, diameter 7. Hab. Twenty miles from Antananarivo (Johnson). The concentric striae are deep and regular upon the umbones; but towards the ventral margin they become less regular and finer, and in front are rather more strongly developed than towards the posterior side. This is the first record of the genus in Madagascar; aud I have not been able to associate the species with any of the forms described from the adjacent continent. SPH^ERIUM MADAGASCARIENSE, Tristram. Spharium madagascariense, Tristram, Proc. Zool. Soc. 1863, p. 61; Sowerby, Conch. Icon. pl. iii. f. 22, bad ! Hab. Two days west of Antananarivo (Tristram); about 20 miles from the capital (Johnson); Betsileo (Cowan). This species is scarcely if at all different from S. capense of Krauss, and is mainly distinguished by difference in locality. The slight compression of the valves towards the circumference, remarked upon by Tristram, is not constant in all specimens, some exhibiting it in a comparatively decided manner, whilst others are rounded at that part just like the South-African form. LlMOSINA FERRUGINEA, KraUSS. Cyclas ferruginea, Krauss, Sudafr. Moll. p. 7, pl. i. f. 7 ; Clessin (as Limosina), Conch. Cab. p. 247, pl. 46. f. 1-4 ; Sowerby (as Spharium), Conch. Icon. f. 47, not good ! Hab. Tbe river Knysna, South Africa (Krauss). About 20 miles from Antananarivo (Johnson). Also Mauritius (Brit. Mus.). |