THE BRITISH NATURALIST'S 



CATALOGUE 



OF THE 



LAND AND FRESH - WATER MOLLUSCA 



OF THE BRITISH ISLANDS. 

 BY T. D. A. COCKERELL. 



Probably most British Botanists, if asked to name the work which 

 conveyed the most useful information to them in the smallest amount 

 of space, would reply " The London Catalogue." The utility of this 

 well-known list of British plants will not be disputed, and it has long 

 seemed to the present writer that a similar list of the Mollusca was a 

 great desideratum. 



The present list has accordingly been compiled, and is intended to 

 give, after the plan of the London Catalogue, a complete enumeration 

 of the species and varieties of inland mollusca known as British, for 

 the purposes of reference and exchange. 



The census-numbers refer to the number of counties and vice- 

 counties, (according to the map published some years ago in " Journal 

 of Conchology "), in which each species has been found. These 

 numbers will give a good idea of the relative frequency of the differ- 

 ent species. Species or varieties which are imperfectly known 

 or doubtfully British are given in italics. 



Some varieties enumerated have not hitherto been recorded as 

 British, but of all such the present writer has seen British specimens. 



It has been found impracticable to distinguish between sub-species, 

 varieties, forms and monstrosities, and for the present these are all 

 classed as varieties : and the varietal names are made to agree in 

 gender with the genera. 



All synonyms have been omitted, except in a few cases where they 

 are necessary to explain a change from the ordinary nomenclature used 



