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JOURNAL 



ASIATIC SOCIETY. 



No. II. 1860. 



Contributions to Indian Malacology , No. I. — By Messrs. W. T. and 

 H. F. Blanford, of the Geological Survey of India. 



In a paper published in the Annuls and Magazine of Natural 

 History for 1S57,* Mr. W. H. Benson gave an able resume of the 

 distribution^ the Cyclostomacew of South-western Asia and of some 

 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 generic distinction between the forms 

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

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

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

 two streams of distinct genera were supposed to extend from the 

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

 eastern, the other through the western peninsula, 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 

 occurred 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 foot of the Himalayas 

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

 fairly 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 Sebies, Vol. XXIN. b 



