CONCHOLOGY. 



103 



Shell. Variable in form, 

 oblong, aperture entire, the 

 mella smooth, of which the 

 truncated. Inhabits South 



Achatina perdix. 



A. immaculata. 



A. acuta. 



A. Mauritania. 



A. ustulata. 



A. virginea. 



A. Marminii. 



A. fusco-lineata. 



A. columnaria. 



A. acicula. 



, but generally subturriculated, oval or 

 right lip sharp, never reflected, colu- 

 anterior extremity is alw^ays open and 

 America. Tvt^enty-four species. 



Achatina zebra. 



A. purpurea. 

 ^ A. bicarinata. 



A. castanea. 



A. vexillum. 



A. Priamus. 



A. Peruviana. 



A. albo-lineata. 



A. fulminea. 



A. folliculus. 

 A. oleacea. 



A. glans.* 



A. solida.* 



A. Vanuxemensis; 



4. Genus Anostoma. PI. X. 

 Animal. See Helix. 



Shell. Somewhat extraordinary in its formation, orbicular, 

 the spire convex and obtuse, aperture round, dentated grinning, 

 turned upwards to the side of the spire, margin of the lip reflected. 

 Lakes in America and the Sandwich Islands. Three species. 

 Anostoma dentata. Anostoma depressa. 



A. clobosa.* 



5. Genus Helicina. PI. X. 



Animal. See Helix. 



Shell. Terrestrial, distinguished only from the Helix by its 

 columella being transverse callous ; much depressed and dimin- 

 ished in thickness at the lower part, subliglobular, imperforate ; 

 aperture entire, demioval, margin acute, forming an angle at the 

 lower base of the right lip ; operculum corneous. Inhabits groves 

 in Europe. Nineteen species. 



Helicina neritella. Helicina rhodostoma. 



