JOURNAL 



ASIATIC SOCIETY 



No. II. 1860. 



Gontributions to Iridian Malacology , JVo. I — By Messrs. W. T. and 

 H. F. Blakeord, of the Geologicál Survey of India. 



In a paper published in the Annals and Magazine of Natural 

 History for 1857,* Mr. W. H. Benson gave an able resume of the 

 distribution of the Cyclostomacew of South-western Asia and of sorne 

 of the neighbouring islands. As regarded their distribution in India, 

 both Cis and Trans-gangetic, it was proved that the evidence then 

 available shewed a considerable generie distinction between the forms 

 of the Indian península with Ceylon on the one hand, and those 

 occupying the Himalayas, the Khasi hills, Burmah, and the Malny 

 countries on the other. It was also attempted to be shevvn that, if 

 two streams of distinct genera vvere supposed to extend frorn the 

 island of Borneo, one raight be imagined to pass up through the 

 eastern, the other through the western península, the valley of the 

 Ganges and the plains of Northern India being the limit of each line. 



At that time it was believed that no single species of land shell 

 oceurred at the same time upon the Himalayas, and in India south of 

 the Ganges. A few widely disseminated species, such as Helix vitri- 

 noides, are certainly to be found at the base of the mountains, as well 

 as universally over the plains, but even at the íbot of the Himalayas 

 a great change takes place in the fauna generally, and when once 

 faiily within the mountains, scarcely a species of the Indian plains 

 recurs. But there are a few exceptions. In the Annals for April, 

 1859, Mr. Benson mentioned the discovery by one of ourselves of 

 * Ann. and Mag. of Nat. Hist. Vol. XIX. p. 201. 



No. CIII. — New Series, Vol. XXIX. a 



