156 PNEUMONOBRANCHIATA. 



with those ofPfeiffer in Ferussac's cabinet; Mr. Jef- 

 freys refers to PfeifFer's figures with doubt, as repre- 

 senting H. concinna ; and Mr. Alder says it is not to be 

 distinguished from it except by its not being hispid in 

 any of its stages. Rossmasler regards H. depilata of 

 Jeffreys as the same as H. sericea and H. glabella, 

 and refers Turton's figure of H. granulata to this 

 species ! 



I do not think the four last species are in any way 

 satisfactorily determined ; they may be only varieties 

 of one another, or there may be more species, but 

 this can only be determined by collecting together a 

 very large number of specimens from their natural 

 situations (not as collected among the rejectamenta 

 of rivers) ; observing how the specimens of the same 

 locality or brood vary, and how the periostraca and 

 the hairiness is affected by their being kept alive, and 

 also by the kind of place they may inhabit. The 

 synonyma of the foreign authors are even more doubt- 

 ful, but this is occasioned by our seldom receiving 

 the same species or variety of these hairy Hydromanes, 

 under the same name, from our foreign correspondents 

 and the dealers. Indeed, the foreign species, judging 

 from the very different synonyma of the continental 

 authors, are as confused as our own. 



40. 22. Helix rufescens. Rufous Snail, (t. 3. f. 28.) 

 Shell flattish, bald, reddish horn-colour, concen- 

 trically striate, slightly carinated by a narrow 

 central paler band ; whorls six ; mouth roundish 

 lunate ; umbilicus large and deep. 



Helix rufescens. Penn. B. Z. f. 34. ; Montagu, p. 



