PELECYPODA—PRIONODESMACEA, 



419 



150. G. congesta (Conrad). Cretacic. 



Differs from G. subaustralis in its smaller size, more elliptical 

 form, and straighter hinge line. 



Ripleyan of New Jersey (Cliffwood-Wenonah), North Carolina. 



Fig. 544. Glycimeris idonea, X f • (Md. Surv. ) 



151. G. idonea (Conrad). (Fig. 544.) Eocenic. 



Larger. Surface marked with obscure radiating striae. 

 Pamunkey of Maryland, Lignitic of Georgia and Alabama. 



XLV. Pterinea Goldfuss. 

 Inequivalve, very inequilateral. Left valve convex ; right valve 

 flat. Hinge margin constricted into ears. Surface radially 

 sculptured or smooth. Ligmental area extending on both 

 sides of the beak and longitudin- 

 ally grooved. Anterior teeth trans- 

 verse ; posterior elongate, nearly 

 parallel to the hinge line. Anterior 

 muscle scar small. Pallial line 

 simple. Ordovicic-Carbonic. 



152. P. demissa (Conrad). (Fig. 



545.) Ordovicic. 



Distinguished by its strong con- 

 centric growth lines and large an- 

 terior ear. 



Cincinnati Group : New York-Iowa ; Wisconsin. 



153. P. emacerata (Conrad). (Fig. 540.) Siluric. 

 Right valve flat, smooth, with striated wing. Left valve convex, 



with strong radii crossed by concentric striae. 



Fig. 545. Pterinea demissa. 

 Ohio, II.) 



(Geol. 



