LIMNJEUS. 205 



shell are in some situations often found reversed, 

 as is the case with the variety recorded by Mr. 

 Bean at Scarborough. It is not uncommon to find 

 some specimens, the spires of which are more or 

 less unrolled, or separated from each other. Indeed, 

 this distortion appears to be more common in this 

 shell than any other British species I am acquainted 

 with. 



Rossmasler (Icon. i. 98.) thinks that Dr. Turton's 

 figure (f. 101.) represents what he considers a species 

 under the name of Limnceus vulgaris, which is not the 

 L. vulgaris of Jeffreys. 



Mr. Jeffreys says, " The young shells of L. acutus 

 are of a more elongated form than those of either L. 

 auricularius or L. pereger. It has a more oblique 

 and less ampullaceous form, and is of a thicker con- 

 sistency than L. auricularius." Mr. Alder regards 

 this variety as intermediate between L. pereger and 

 L. auricularius^ and says that, if it is not a distinct 

 species, it may lead us to unite them all into one. 

 It comes very near L. lineatus of Mr. Bean. The 

 single specimen we have in the British Museum, 

 from Mr. Alder, leads me here to consider it only 

 a variety of L. pereger, as it much resembles a com- 

 mon London variety of that shell ; and I still think 

 L. auricularius is a species. 



The Gulnaria lacustris of Leach is very peculiar, 

 from the erosion of its tips, probably arising from its 

 locality, the lakes of Cumberland. We have very 

 similar, but rather darker and thicker shells, with 

 tips perfect, from Lough Neagh, Ireland. 



The latter variety may prove a distinct species, 



