138 Contributions to Indian Malacology. [No. 2, 



sinuously costulated. Spire ovately turrited, apex rather acute, suture 

 much impressed. Whorls 8^, convex, the last a little smaller, quite 

 free from the other whorls for a short distance behind the mouth, 

 but not descending much, not nearly so far as O. tortuosus is repre- 

 sented as doing. The basal keel is strong, compressed, transversely 

 ribbed, and becoming larger in front ; the space inside the keel around 

 the umbilicus is of moderate size and ribbed. Aperture nearly 

 circular, and almost vertical, the opening of the basal canal being 

 at the left side and not in the same plane as the aperture, but turned 

 a little downwards and to the right. Peristome thickened double, 

 the inner portion obtuse, the outer expanded, turned back, produced 

 below the canal and above near the suture, narrower on the inner 

 margin and not touching the penultimate whorl. Operculum un- 

 known. Measurements of 3 specimens in decimals of an inch. 



Length, Major diameter, minor diameter, width of 



peristome included, aperture inside, 



0.84 0.28 * 0.14 



0.76 0.26 0.23 0.14 



0.64 0.23 0.2 0.12. 



Length of the aperture and outer peristome in the larger specimen 

 from the base of the canal to the end of the projection above 0.26 

 inch. 



At first sight, this shell bears a most striking resemblance to C. 

 tortuosus, Chem., but the last whorl is much less produced, and there 

 appear, judging from the description and figures of Chemnitz's species, 

 to be several slight but not unimportant distinctions in sculpture and 

 form. Amongst the Ceylonese species, the nearest approach to the 

 present is made by C. decorus, Bens., and O. JBIanfordi, Dohrn, but 

 no Ceylonese kind is known with the last whorl free. The previously 

 described Cataulus from the base of the Anamullay hills resembles 

 C. Calcadensis in the sinistral position of the keel, a character not 

 noticed by Pfeiffer in his description. 



Since finding the present species I learn from Captain Beddome 

 that he has met with a third Indian Cataulus in Travancore. 



So far as I am aware, the Nicobar locality of Cataulus tortuosus has 

 not been confirmed. The discovery of so closely allied a form as that 

 now described, in Southern India tends to make it probable that the 



