122 LIMN^BID^E. 



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

 to treat of the next species. 



B. Body dextral. Shell sinistral. 

 2. A. LACUS'TRIS*, Linne*. 



Patella lacustris, Linn. Syst. Nat. ed. x. i. p. 783. A. oblongus, 

 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 yellow specks inter- 

 spersed among the black ones. 



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

 greyish-horncolour, very finely but indistinctly striate as in 

 A. fluviatilis, but without the intermediate ridges : anterior 

 margin very little narrower than the other : epidermis thick : 

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

 placed close to the margin : mouth oblong : outer lip membra- 

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



Var. 1 . compressa. 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 

 throughout 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 (Warren). 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. 



