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Show 1882.] MOLLUSCAN F A U N A O F M A D A G A S C A R . 381 united to the outer lip by a very thin granulated callosity, coating the whorl within the aperture. Greatest diameter 76 millim., smallest 58, height (resting on its base) 35. Hab. Ekongo, South-east Madagascar (Waters). This is the species erroneously considered by Mr. Angas to be the H. guestieriana of Crosse, which much more closely resembles II. ibaraoensis of the former author. II. guestieriana is a more globose shell, with a higher penultimate whorl, a shorter aperture, a smooth columella, and a smooth callosity upon the body-whorl, which is encircled by several slightly raised ridges of more equal size than in H. bicingulata. The granular and slightly arched-forward columella in the latter species, the obliquely indented surface of the body-whorl, and the two very conspicuous brown slightly raised girdles around it, the lower one bordered by an indistinct pale one above, distinguish this from the allied forms, H. cornu-giganteum, H. betsileoensis, H. ibaraoensis, and H. guestieriana. The first two openly umbilicated, the third generally imperforate (in about fifty specimens I have seen a few with a narrow perforation) ; and the last is said to be " narrowly subrimate." H. betsileoensis has the columella granular as in the present species; in the other three it is smooth. In H. ibaraoensis the callus uniting the columella and the outer lip and spreading over the whorl within the aperture is conspicuously granulated, and the epidermis is nearly black towards the lip. All the five species here remarked upon are, no doubt, offshoots from one original progenitor ; still I have found no difficulty in recognizing any specimen which has yet been examined. Probably no two exist in precisely the same locality. The following is the distribution as at present known :- H. cornu-giganteum. Hab. Island of Agalega, N.E. of Madagascar (teste Sir David Barclay !). H. guestieriana. Hab. Madagascar (no precise locality known). H. betsileoensis. Hab. S.E. Betsileo (Angas) ; Tanala country (Deans Cowan). H. ibaraoensis. Hab. S.E. Betsileo (Angas) ; Tanala country (Deans Cowan). H. bicingulata. Hab. Ekongo, south-east of the island (Waters). HELIX (MACROCYCLIS ?) COVANI, Smith. (Plate XXI. figs. 10-12.) Helix (Macrocyclis 1) covani, Smith, Journ. of Conch, vol. ii. p. 338. Hab. Ankafana, Betsileo province (Cowan). This species was originally described from a single specimen which |