JOURNAL OF CONCHOLOGY. 49 



THE CONCHOLOGICAL SOCIETY'S LIST OF 

 BRITISH LAND AND FRESHWATER MOLLUSCA, 



1892. 



The Committee (consisting of Messrs. William Nelson, 

 Wm. Denison Roebuck, and John W. Taj'lor) appointed to 

 prepare a new edition of this List, have been guided in the 

 execution of their task by the desire to make as little change as 

 possible, consistent with the necessity of bringing the list up to 

 the level of our present knowledge of the subject, and they have 

 therefore considered it their duty to make only such changes in 

 the nomenclature as they had personally satisfied themselves 

 as to the necessity of, while in cases where there existed 

 conflict of authority as to the desirability of change, no 

 alteration has been made, pending the agreement of the 

 conflicting authorities, or the opportunity for personal investiga- 

 tion of the original works. 



Explanations. 



Arrangement : — The artificial separation of the land 

 from the fresh water species has been discontinued, and a more 

 natural arrangement adopted, as showing in a more striking 

 manner the inter-relationship of the different genera. 



Nomenclature : — This has been carefully examined, and 

 revised where necessary. 



The Authorities for Specific Names have been 

 carefully revised, and the practice of enclosing them within 

 parentheses has been adopted in the case of species which were 

 originally described as of a different genus to that now used : 

 e.g., Arion ater (L.) was described as a Limax, while Helix 

 Jiispida L. retains its original generic allocation. 



Square Brackets [ ] are used to denote species whose 

 claim to rank as British is not yet thoroughly established, as in 

 the case of Hyalinia petroneUa. 



Monstrosities, although of no very great importance, 

 are included in the list, placed after the varieties of each species. 



