74 Proceedings of the Asiatic Society. 



of water plants, &c, not unfrequently adhering to the feet of water 

 fowl, as mentioned in his work on the origin of species, and had sug- 

 gested that the eggs and fry of fresh water mollusca might occasion- 

 ally be transported in this way. Mr. Blanford has found that those 

 MelaniadcB such as the Tanalia, the Philopotamis and those species 

 of Melania , such as M. terebra, and M. Hugelii that inhabit mountain 

 streams, (which are rarely or never visited by water fowl,) are extremely 

 restricted in distribution, and when a number of neighbouring streams 

 are tenanted by the same species, that each stream has frequently a 

 distinct variety or series of varieties. The low country species on the 

 contrary, and generally those inhabiting tanks and jheels, such as 

 Paludomus Tanjoriensis and Melania tuberculata, have in all cases a 

 very wide distribution. Estuarine species such as Melania aculeata 

 Chemnitz are equally widely distributed. The last mentioned species 

 ranges from the Navigator's Islands, (from which specimens exist in 

 the Society's Museum,) to the West Coast of Africa, and the same 

 species had been found by himself in Southern India and Ceylon. By 

 attention to such facts as these, Mr. Blanford thought that the at present 

 exceptional case of fresh water mollusca, would eventually be found 

 to conform to the general rule, that in cases of wide distribution, some 

 means of transport exist, although not apprehensible at the first glance. 



