The Conchologist 



VOLUME II. 



SOME REMARKS ON THE DISTRIBUTION 



OF 



BRITISH LAND AND FRESHWATER MOLLUSCA. 



By R. F. SCHARFF, Ph.D., B.Sc, M.R.I.A., 

 Natttral History Museum, Dublin. 



One of the most important objects to be gained in collecting British 

 Land and Freshwater Mollusca is to supply data to enable us to 

 draw conclusions as to their origin. If we can discover approxi- 

 mately the period at which some of them migrated to England from 

 the Continent, we shall have solved an extremely interesting 

 zoological problem. 



But these results are not to be attained by collecting information 

 only of the range of Mollusca now living in the British Isles ; we 

 must also study their distribution in past times, extending our 

 researches to Continental Europe as well. It is evident that during 

 these investigations, in order to be able to draw any satisfactory 

 conclusions, we must, as far as possible, keep step with Continental 

 authorities. British Conchologists, as a rule, are apt to be too 

 conservative in nomenclature, as Mr. E. A. Smith* has justly 

 remarked in his recent address to the Conchological Society. 



In more recent geological times (as Mr. Quiltert has already 

 pointed out in the ist vol. of "The Conchologist") the glacial 

 period no doubt played a very important part in the distribution of 

 British Non-Marine Mollusca. Many geologists hold that almost 

 the whole of the British Islands were covered thousands of feet deep 



* On the nomenclature of certain Genera of British L. & F. Shells. Jour, of Conch., vol. vi., 1891. 



t The glacial period and British Non-Marine Mollusca. Conchologist, vol. i., 1891. 

 Conchologist, Vol. ii. p. i., 18Q2. 



