294 TAYLOR : ON THE VARIATION OF MOLLUSCA. 



expressive forms of a species. To those holding broad views, 

 students of the subject generally, or the ordinary naturalist, the 

 varietal names need never be used, but to the specialist it is not 

 only a great convenience, but a necessity to be able to refer with 

 precision to the leading variations to which a species is liable. 

 As reasonably might we expect a resident in London or else- 

 where, to be able to get along with no better knowledge of his 

 neighbourhood than the general student of topography would 

 possess. 



At the same time I would deprecate the undue multiplica- 

 tion of varieties. Too great a degree of division in this subject 

 would in my opinion defeat its own purpose, from the difficulty 

 of exactly identifying and referring the various forms. 



Specific identification is itself often far from easy to satis- 

 factorily accomplish, thus though Lt?nncea aiiricularia and L. 

 peregra are universally allowed to be perfectly distinct species, 

 specimens are occasionally met with, which can only be doubt- 

 fully referred to one or the other species. I am aware that 

 Lovell Reeve in his " British Land and Freshwater Mollusks " 

 remarks that " there is no fear of mistaking the most widely 

 inflated form of LimncBa limosa for L. auricular ia^^ but I appre- 

 hend he spoke with an insufiicient and imperfect knowledge of 

 the variability of species. 



Other instances of similar approximations of good species 

 will suggest themselves to every thoughtful and experienced 

 conchologist. 



While fully appreciating the excellent work the numerous 

 able Continental conchologists have accomplished, and are still 

 accomplishing, and though in entire accord and sympathy with 

 their aim, which is to direct more minute attention to the diver- 

 gencies existing amongst mollusks, the method of nomenclature 

 they adopt, does not seem to me to be well adapted to render 

 their labours so widely useful as they might be. Their practice 

 of giving to these divergent forms, distinct specific names, which 

 names are however' I believe, generally speaking, allowed to be 



J.C, v., April, 1888. 



