It is proposed to accumulate Materials for a New and 

 Comprehensive 



flbonogvapb of the 



Xanb anb jf reebwater flboUusca 

 of the Btitisb jfauna 



and it is desired to enlist the assistance of all persons interested 

 in the detailed and exhaustive study of the species and varieties 

 of British MoUusca. 



Very special attention will be paid to the Variation and 

 Geographical Distribution of the various forms, and the design 

 of the proposed work will include as complete an account 

 of each species as can be framed, no part of the subject being 

 passed over or omitted. Into the subject of 



Variation 

 it is proposed to enter in a full and elaborate manner, treating 

 of the modification of each species throughout its entire geo- 

 graphical range. The work would thus include an account not 

 merely of the varieties which have actually been described as 

 British, but also of those variations of British species which 

 occur in other countries. The fast-growing importance of this 

 branch of study, bearing as it does upon the solution of 

 some of the most important questions which philosophical 

 naturalists have yet to deal with, amply justifies the preparation 

 of a work in which it shall constitute one of the salient features, 

 and the writers feel confident that in attempting to deal with 

 it they will serve the truest interests of science. 



It is proposed to notice all variations and the circumstances 

 under which they occur, so far as it can be done. And as the. 

 systematic use of definite names greatly simplifies and tacilitates 

 the study of the realities to which they apply, pretty much 



