PULMONARY GASTEROPODS. 



409 



dantly amid the grass and shrubs near brooks round Paris and else- 

 where. It is Succinea putris, presenting a small, thin, diaphanous 

 shell of a pale amber yellow, marked with close and very fine longi- 

 tudinal stripes (Fig. 208). The Achatina zebra of Chemnitz is a 



Figs. 206 and 207. Pupa uva. 



great snail, which devours shrubs and trees in Madagascar (Fig. 

 209). Finally, Vitrina, the shell of which is very small and very 

 thin in some species so small, indeed, in Vitrina fasciaia (Fig. 210), 

 that the animal cannot fully enter the shell occupies a point of transi- 

 tion between Helix and Limax. 



Fig. 208. Succinea putris 

 (Linnaeus). 



Fig. 209. Achatina zebra 

 (Chemnitz). 



Fig. 210. Vitrina fasciata 

 (Ed. and Soul). 



In the Pectinibranchial Gasteropods the gills are composed of 

 numerous leaflets cut like the teeth of a comb, and attached, on one 

 or many lines, to the upper part of the respiratory cavity. They 

 constitute the most numerous order of Cephalous Molluscs, compre- 

 hending nearly all the univalve spiral shells, and many others which 

 are simply conical. They inhabit the sea, rivers, and lakes, and are 



