240 



THE HABITATS OF FRESHWATER MOLLUSCA. 



By a. E. boycott, M.A., D.M., F.R.S. 



(Presidential Address delivered at the Annual Meeting, October 13th, 1917). 



Those of us whose interests in conchology lie chiefly in the study of 

 British land and freshwater niollusca are hardly in a position to make 

 any substantial contribution to systematics, and our predatory passion 

 to catch an unfamiliar sort finds infrequent gratification. But the 

 paucity of species in our own fauna removes to a large extent the 

 incubus of a collection, and incites us to try and achieve some new 





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Sketch map of watery habitats of Aldenham Parish. Squares indicate running, circles 

 closed ponds. The distribution of Sphcerium lacustre is also shown. Scale one mile. 



knowledge out of what material is at hand, rather than do once more 

 what has been done often enough already. The intensive study of 

 the three or four score species which most of us have in our neigh- 

 bourhood opens up ample fields of enquiry — variation, habits, food, 

 breeding, anatomy, distribution, and what not — which are of obvious 

 biological importance, and which have not, I think, received all the 

 attention they deserve. 



