ON BRITISH PULMONIFEROUS MOLLUSCA. 



141 



mals under review. Unfortunately a great part of the Euro- 

 pean species were named contemporaneously by Montagu in 

 England, and by Draparnaud in France, and several years 

 elapsed before it was possible to compare their nomenclatures. 

 In the mean time that of the former had become universal 

 among British authors, and that of the latter among Conti- 

 nental, and much confusion has arisen in consequence. Of late 

 there has been a tendency among British authors to adopt 

 Draparnaud's names, and among Continental writers to use 

 those of Montagu. Another cause of difficulty has arisen from 

 the very different views entertained by authors as to the spe- 

 cific claims of the forms they describe, some elevating every 

 little variation to the rank of a species, others attempting defi- 

 nitions more in accordance with the philosophy of natural 

 history. Writers acquainted only with the animals of their 

 own country or district, are especially apt to blunder on this 

 point, and to constitute every local variety a species. The 

 error is luckily on the safe side : it is better that every varia- 

 tion should be dignified as a species for a time, than that any 

 one form be past over. In the following table, exhibiting a 

 comparison of the principal published European lists, allow- 

 ances must be made for the above reasons, though to a certain 

 extent I have endeavoured to correct it. I may mention that 

 Krynicki's Russian list includes the Caucasus. The French 

 list may be regarded as slightly over-stated, several of Mi- 

 chaud's species being probably supposititious. Deduct one 

 Limneus from the British list, and there remain the numbers 

 for England alone. 



British Isles 



Scotland 



France (Michaud) ... 



Sweden (Wilson) 



Brabant (Kickx) 



Switzerland (Char-"1 



pentier) J 



Italy, exclusive of Si- "1 



oily (Jan) J 



Thetwo Sicilies (Phi-] 



lippi) J 



Germany (Pfeiffer) ... 

 Russia, with the Cau- 1 



casus (Krynicki) J 



H >iE 



CM u 



12 5 

 1 



25 11 

 64 

 12 6 



2111 



i 

 1310 



.j. 



1517 

 1615 



5 

 10 



Ph Cl, 



112 

 13 2 



