184 



cated, and the margin of the aperture never thickened, 

 which seems to indicate, that the animal breathes only 

 air, and though not altogether incapable of existing in an 

 aqueous element, probably derives its sustenance from 

 the vegetation on the banks of rivers or stagnant pools, 

 and only occasionally ventures into the water. Shell 

 oval or oblong, ventricose, striated longitudinally; aper- 

 ture ovate, never thickened or reflected: a smooth, 

 straight columella, truncated at the base, without an 

 operculum. Lamarck has not mentioned that they are 

 oviparous, which no doubt is the fact, as the writer has 

 seen the ovum of one species resembling the egg of a 

 large sized humming-bird, and containing a distinctly 

 formed shell within. Several of these, like the shells 

 of the preceding genus, are heterostrophe. After the 

 A. fulminea, Lamarck has now placed the A. columua- 

 ria, having determined it to belong more properly to 

 this genus than to that of the Lymnaea, from which it 

 has therefore been removed. 



Last Whorl of the Shells ventricose, and not 

 compressed. 



Achatina perdix Achatina immaculala 

 zebra purpurea 



