CONCHOLOGIA CESTRICA. 



75 



DIAGRAM OF THE GENERA, AND SPECIES, OF THE FAMILIES VIVI- 

 PAR1D/E, VALVATID^E, AMNICOLID^E, AND STREPOMATID^. 



FAMILY. 

 VIVIPARID^E. 

 VALVATID^E. 



AMNICOLID.E. 



STREPOMATID^E. 



ANCULOSA. 



dissimilis. 



Sub-genus MELANTHO, BOWDITCH, 1822. 



Animal of Melantho. [W. G. B.] 

 Fig, 152, 



Shell, thick, solid, ovate imperforate ; whorls rounded, 

 smooth ; peristome simple, continuous. 



Animal, with the foot broad, and thin, produced 

 beyond the rostrum, which is short and truncated ; 

 operculum concentric. 



M. decisa, SAY. 



Paludina decisa, Say, Nich. Encyc., 1st Amer. Edit, 

 1817. 



Shell, elongate ovate ; whorls 4, wrinkled across, and 

 with minute revolving striae ; aperture ovate, more than 

 half the length of the last whorl ; epidermis green ; 



