168 PNEUMONOBRANCHIATA. 



Inhab. ditches and wet places, among dead leaves. 



Shell half the size of the last, of a pale and hardly 

 transparent brown horn-colour, slightly striate, equally 

 convex on both sides, with the apex usually whitish 

 as if decorticated, with four well defined volutions ; 

 aperture roundish crescent-shaped, as long as it is 

 wide. 



Dr. Leach considered this as the young of the last 

 species, from which it evidently differs in colour, ap- 

 pearance, and locality, as the two species are never 

 found together. It is much flatter and more trans- 

 parent ; it has only four volutions ; and the aperture 

 is not so circular. 



Mr. Jeffreys says (Linn. Trans, xiii. 512.) that M. 

 D'Orbigny has informed him that the Helix pygmcea 

 of Draparnaud is our H. umbilicata, and not our H. 

 pygmcea. 



Mr. Alder says, notwithstanding the information 

 communicated by M. D'Orbigny to Mr. Jeffreys, he 

 still holds the opinion that this is the true H. pygmcea 

 of Draparnaud ; many naturalists, he says, have erro- 

 neously considered it to be the young of H. umbili- 

 cata Mont. 



This species was first noticed as British in the 

 Medical Repository for 1821. It is very distinct from 

 the preceding. 



b. Hyaline Ferns. 

 Shell greenish or pale broivn, hyaline, polished, smoothish. 



48.4. Zonites alliarius. Garlic Snail, (t. 4. f. 39.) 

 Shell nearly flat, slightly globular, thin, transpa- 

 rent, horn-coloured, very shining, nearly smooth; 



