05 CONCHOLOGIA CESTRICA. 



narrow, rounded; posterior, broad and rounded; dorsal 

 margin elevated behind the hinge ; inferior curved ; 

 beaks moderate ; epidermis mostly greenish - yellow, 

 with numerous broad, dark-green rays;, interior yellow- 

 ish, and iridescent ; cardinal teeth bifid, crenulated, and 

 oblique. H. 2-2^, W. 3-4, T. i-itf, inches. 

 Station, Schuylkill River, Chester County. 



U. cariosus, SAY, Nich. Encyc., 1st Amer. Ed., ( 

 1816. 



TT. cariosus. 

 Pig, 183. 



Shell, valves rather thin, sub-oval, inflated; hinge 

 margin elevated, base curved; anterior end short, 

 rounded, posterior narrowly rounded; the posterior 

 dorsal slope sometimes with four, or five, fine inter- 

 rupted wrinkles, and green rays ; beaks at one-fourth 

 from the anterior end ; yellow or greenish ; inside 

 bluish-white ; cardinal teeth long, compressed, oblique, 

 crenate. H. 2.5, W. 3.5, L. 1.75, inches. 



Station, Schuylkill, Delaware, and Susquehanna Riv- 

 ers ; common. 



