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.
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