134 Contributions to Indian Malacology. [No. 2, 



Contributions to Indian Malacology, No. VII. List of species of 

 Unio and Anodonta described as occurring in India, Ceylon and 

 Burma.— By William T. Blanford, A. B. S. 31., F. G. S. 

 [Received 5th September, 1866.] 



There are few genera in the whole range of natural history more 

 puzzling than Unio and Anodonta. Every naturalist who has at- 

 tended to them has been struck by the great variation of which the 

 different species are susceptible, though it is to be regretted that this 

 knowledge does not appear to have had much influence in restraining 

 some naturalists from recording as distinct species isolated specimens 

 which reached them from distant countries, and which only differed 

 from other specimens in characters of very doubtful specific value. 



Although the Unio aides of the Indian waters are far behind those 

 of some countries, and especially of America, in the amount of vari- 

 ation which they exhibit, amply sufficient is shewn to render them 

 very difficult to classify. And as the question of variation is one of 

 the most important, especially at the present day, in the whole range 

 of zoological science, those animals which, in the wild state, exhibit 

 the greatest amount of variation, are peculiarly worthy of study. 



In endeavouring to classify the Indian shells, one great difficulty 

 that I have found, has been the determination of described types. 

 Descriptions of Indian Unionidce are scattered through many works, 

 not easily procurable in India. There are, probably, yet a few to 

 which I have not had access, but as I have been able to compile a 

 list, comprising, I believe, a very large majority of the published 

 forms, I think that I shall be aiding any one who, in India, may be 

 engaged in the same study, by printing the list, with references to the 

 original descriptions and to figures, whenever such exist, and by 

 adding such remarks as appear to be necessary. 



I also hope to be able to publish figures of a considerable propor- 

 tion of the species named ; in some cases, copies of the original illus- 

 trations ; in others, drawings of authentic specimens. I shall feel 

 greatly indebted to any one who will aid me in this endeavour by 

 furnishing me with typical forms, or with any specimens from distant 

 parts of the country. In all such cases, a small series of the varieties 

 and different ages is desirable. 



