XX. THE BANDED POND-SNAIL OF INDIA 

 {V I V I PA R A BENGALENSIS). 



By N. Annandale, D.Sc, F.A.S.B., Director, Zoological Survey 



of India and R. B. Seymour Sewell, B.A., F.A.S.B., 



I. M.S., Surgeon Naturalist, Indian Marine Survey 



and lately Offg. Superintendent, Zoological 



Survey of India. 



(Plates I— III). 



PREFATORY NOTE. 



In writing this paper our main object has been to provide 

 an introduction to the systematic study of the freshwater 

 Gasteropod molluscs of India. In no single species had the 

 anatomy of the animal been studied in detail, and very little was 

 known about the life-history of any one form. Even for the 

 common European species comparatively little information was 

 available, and there is much indirect evidence that, in bionomics at 

 any rate, considerable differences exist, between tropical molluscs 

 and those of temperate climates allied to them taxonomically. 

 In the circumstances a minute comparative study was impossible 

 and we have thought it better, while citing all relevant references 

 to literature available to us, to deal precisely with one species as 

 an isolated unit in the fauna, rather than to generalize on resem- 

 blances and differences prematurely. In only one part of the 

 paper has this system been departed from to any great extent, 

 namely in that on the edge of the mantle and the ornamentation 

 of the shell. Here the comparative method was inevitable within 

 the limits of the family, and it so chanced that abundant material 

 was available both from within the limits of the Indian Empire 

 and from a Chinese district on its eastern confines. 



Our work has been undertaken in connection with the survey 

 of the freshwater molluscs of India inaugurated at the request of 

 the medical authorities in 1918 by Dr. S. W. Kemp and one of 

 ourselves. There is one point to which we invite attention — that 

 our paper is taxonomic in intention, but could have beeri prepared 

 only in India and not without a study of the anatomj^ and biono- 

 mics of the species with which it deals. It has been held that sys- 

 tematic zoology is incompatible with bionomics and that different 

 types of mind are necessary- in their study. Against such views we 

 protest. They are a libel on taxonomists, if not on taxonomy. 



Our thanks are due to the artists of the Zoological Survey of 

 India for the great help they have given us in the preparation of 

 text-figures and plates. 



