PREFACE. 



The Land and Freshwater Mollusks of the British Isles have been 

 ably described by Turton, Gray, Forbes and Hanley, Jeffreys, and 

 others, as a fauna -per se ; and great attention has been lavished 

 on details of form and colour, of local habitation, and of parts of the 

 anatomy. French conchologists, commencing- at the opening of the 

 present century with the terse and philosophic Draparnaud, and 

 terminating with the accomplished Moquin-Tandon, have done even 

 more for the natural history of our mollusks, while treating of them 

 as members of the fauna of France, than has been done by British 

 authors. But neither the conchologists of France nor of Britain 

 have worked out the distribution or representation of the European 

 genera and species, and the resulting phenomena, in other parts of 

 the world. It is on this ground that I venture to add another to 

 the already numerous manuals on the subject. 



The bent of a long experience in foreign conchology, has led me 

 to the study of our native Land and Freshwater Mollusks with 

 especial reference to their relation with those of other countries. 

 The genera of our. own latitude are in this Work collated with 

 the similar or representative genera of other latitudes. The species 

 are regarded in their true character of an outlying fragment of that 

 great province of distribution, elsewhere called the Caucasian Pro- 

 vince, which has its centre of creation on the confines of Europe 

 and Asia Minor, and extends on either side from Finland to North 

 Africa, and from Arctic Siberia to the Himalayas. I have not, 



