H 



Bryant Walkkr 



Subgenus PLANORBULA Haldeman, 1842. 

 Shell rather small, whorls few, slowly and regularly increasing, rounded 

 or carinated above and below; aperture somewhat expanded, lip more or 

 less thickened within; a single persistent set of 6 dentiform 

 lamellje at short distance within the aperture. 



Fig- 35 Fig- 36 Fig- 37 



Type: Planorhis armigenis Say, lig. 35. Aperture, fig. 36. Radula, fig. 37. 



Subfamily POMPIiOUGINyE Dall, 1866. ' 



Shell spiral, dextral, flattened above ; the body whorl very large. 



Animal sinistral. Tentacles moderate, stout, cylindrical, slightly globose 

 at the tips; eyes sessile, near the inner base of the tentacles; foot short, 

 bluntly rounded behind; jaw single, subcordiform; radula with the teeth in 

 nearly horizontal rows, central tooth small, bicuspid, laterals wide. 



Key to the genera of Pompholigince. 



1. Shell imperforate Pompholyx. 



2. Shell deeply umbilicate Carinifex. 



Genus POMPHOLYX Lea, 1856. 



Shell spiral, dextral, globosely depressed, imperforate ; 

 whorls few, spire short, obtuse; last whorl very wide, ventri- 

 cose ; aperture very large, wide, subcircular, expanded; lip 

 thin ; columella thickened. 



Animal as in the subfamily. 



Type : P. effusa Lea, fig. 38. Radula, fig. 39. 



Fig. 38 



Fig. 39 



