1882. | MOLLUSCAN FAUNA OF MADAGASCAR. 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 H. 
ibaraoensis of the former author. H. 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. bet- 
sileoensis, H. ibaracensis, and H. guestieriana. The first two are 
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. detsileoensis 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 con- 
spicuously 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 recog- 
nizing any specimen which has yet beenexamined, Probably no two 
exist in precisely the same locality. The following is the distribution 
as at present known :— 
A. cornu-giganteum. 
Hab. Island of Agalega, N.E. of Madagascar (teste Sir David 
Barclay !). 
H. guestieriana. 
Hab. Madagascar (no precise locality known). 
H. betsilevensis. 
Hab. S.E. Betsileo (Angas) ; Tanala country (Deans Cowan). 
H. ibaraoensis. 
Hab. 8.E. Betsileo (dngas) ; Tanala country (Deans Cowan). 
Hi. bicingulata. 
Hab. Ekongo, south-east of the island (Waters). 
Heurx (Macrocycris?) covani, Smith. (Plate XXI. figs. 
10-12.) 
Helix (Macrocyclis?) covani, Smith, Journ. of Conch. vol. ii. 
p. 338. 
Hab. Ankafana, Betsileo province (Cowan). 
This species was originally described from a single specimen which 
