122 LIMN^ID^. 



but I will defer my remarks as to this name until I have 

 to treat of the next species. 



B. Body dextral. SheU sinistral. 

 2. A. lacus'tris*, Linne. 



Patella lacicstris, Linn. Syst, Nat. ed. x. i. p. 783. A. ohlongus, F. & H. iv. 

 p. 188, pi. cxxii. f. 5. 



Body yellowish -grey with a greenish tinge, covered with 

 minute and indistinct dark specks : tentacles thick, pointed at 

 the tips : eyes as in the last species : foot truncate in front and 

 very round behind, having a few yeUow specks interspersed 

 among the black ones. 



Shell oblong, obliquely twisted to the left, thin, glossy 

 greyish-horncolour, very finely but indistinctly striate as in 

 A.flimatilis,\)\\i^\\ih.o\ii the intermediate ridges: anterior 

 margin very little narrower than the other: epidermis thick : 

 heak sharp and ridge-like, turning obliquely to the left, but 

 placed close to the margin : mouth oblong : outer lij) membra- 

 nous, reflected. L. 0-25. B. 0-1. 



Var. ].. comprcssa. Shell rather larger, and considerably 

 broader and flatter, than usual. 



Var. 2. albida. Shell milk-white, with a light-grey epi- 

 dermis. 



Habitat : On the under side of the leaves of water-lilies 

 and other aquatic plants^ as well as on fallen leaves of 

 trees, in slow rivers, lakes, canals, marshes, and ponds 

 tliroughout the greater part of the kingdom as far north 

 as Aberdeenshire. It is, however, a local species. 

 Var. 1. Dunstall, Staffordshire (J. G. J.). Var. 2. 

 Grand Canal, Dublin (W^arren). It is also one of our 

 upper tertiary fossils. Its foreign distribution is the 

 same as that of the last species. 



Miiller states that this is not only a freshwater but a 

 marine shell, having taken it alive and adhering to marine 



* Inhabiting lakes. 



