CONCHOLOGY. 103 
Shell. Variable in form, but generally subturriculated, oval or 
oblong, aperture entire, the right lip sharp, never reflected, colu- 
mella smooth, of which the anterior extremity is always open and 
truncated. Inhabits South America. T'wenty-four species. 
Achatina perdix. 
A. immaculata. 
A. acuta. 
A. Mauritania. 
A. ustulata. 
A. virginea. 
A. Marminii. 
A. fusco-lineata. 
A. columnaria. 
Achatina zebra. 
A. purpurea. 
A. bicarinata. 
A. castanea. 
A. vexillum. 
A. Priamus. 
A. Peruviana. 
A. albo-lineata. 
A. fulminea. 
A. acicula. A, folliculus. 
A. oleacea. 
A. glans.* A. Vanuxemensis.* - 
A. solida.* 
4. Genus Anostoma. Pl. 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. globosa.* 
5. Genus Helicina. Pl. X. f 
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, 
