197 



but has been found in brackish water, and even 

 where it is quite saline; the animal breathes only wa- 

 ter like that of the Valvata to which it nearly approxi- 

 mates, but has the Branchiae internal. Shell with 

 round or convex whorls compressing the spiral cavity; 

 aperture a rounded oval, angular at the summit; the two 

 edges of the lip united, sharp, never reflected outward- 

 ly; the operculum horny and orbicular. 



Paludina vivipara Paludina unicolor 



achatina impura 



Bengalensis muriatica 



Paludina viridis. 



AMPULLAR1A. 



HELIX AMPULLACEA. Limi. 



Sowerbys Genera, No. 4, pi. 3. 



This genus appears to be allied to the G. Planorbis, 

 but the shells are very different. They inhabit fresh 

 water in hot climates, and sometimes attain a great 

 size; the columella lip is thickened, projecting, and 

 recurved or reflected over the umbilicus, which is 

 small, forming a compressed funnel-shaped aperture, 

 without producing any callosity within; the right side 

 of the margin is always smooth and sharp. Shell glo- 



