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Show 294 MR. E. A. SMITH ON SHELLS FROM [Feb. 15, 39. PALUDINA ROBERTSONI, Frauenfeld. Paludina robertsoni, Frauenfeld, P.Z.S. 1865, p. 659; Smith, P. Z. S. 1877, p. 717, pi. 74. f. 5, 6. Hab. Same as the preceding. The specimens collected by Mr. Thomson are greenish olive, with the angulation of the whorls strongly marked, and the columella of a bluish tint. 40. PALUDOMUS FERRUGINEUS, Lea. (Plate XXXIV. fig. 29.) Melania ferruginea, Lea, Proc. Zool. Soc. 1850, p. 182; Reeve, Con. Icon. fig. 147; Martens, Von der Decke.i's Reisen in Ost- Afrika, vol. iii. p. 153. Melania zanguebarica, Petit, Journ. de Conch, vol. ii. p. 263, pi. 7. f. 1. Hab. Between Lake Nyassa and the east coast (Thomson); Umba {Craven) ; Zanzibar {Lea). The specimen figured in the ' Conchologia Iconica' is small in comparison with those collected by Mr. Thomson, the largest of which, if the apex were complete, would have a length of about 42 millims, and in diameter it is 17. In the original description Lea describes the single shell which was submitted to him as " ferruginea," and does not mention the dark zone round the middle of the body-whorl. This, although very obscure, is visible in the specimen referred to, now in the British Museum. In shells in good condition two other bands are observable within the aperture- one above, close to the suture, and the other near the base. Melania zanguebarica of Petit appears to be the same as this species ; and Paludomus africanus of Martens, if not identical, offers but slight distinctions. 41. PLANORBIS SUDANICUS, Martens. This species was also recorded in m y previous paper (Proc. Zool. Soc. 1880, p. 349) on Lake-Tanganyika shells. 42. SEGMENTINA (PLANORBULA) ALEXANDRINA, Ehrenberg, var. TANGANYICENSIS. (Plate X X X I V . figs. 30-30 b.) Shell moderately depressed, equally umbilicated on both sides, obtusely angular at the periphery, distinctly keeled on the top of the whorls, and angulated around the umbilicus, brownish horn-colour, spirally finely striated and more distinctly by the incremental lines. Whorls 5 ; aperture irregularly lunate. Peristome strengthened within with a whitish rib. Height of largest specimen 4 millims., greatest diameter 12; aperture 4 high, 3| broad. Another is 10 wide and 3| high. Hab. Lake Tanganyika {Thomson). The four shells before me are constant in the characters above given, and might therefore be specifically distinguished from the P. alexandrina of Ehrenberg. The normal form of that species has the whorls rounded above, is a trifle flatter, and consequently not |
