PELECYPODA—ANOMALODESMACEA. 



d 



529 



Fig. 717. a, b, Cimiiaria recurva, right and cardinal views; c, C. angulata, left 

 valve ; d, C. corrugata. (N. Y. Surv. ) 



Surface marked with radiating ribs (feeble in the posterior dorsal 

 region), crossed by concentric striae. Umbos prominent. Liga- 

 ment external. Hinge without teeth or with an obscure thicken- 

 ing. Adductor scars feeble. Pallial sinus deep. Jurassic— Recent. 



462. P. sancti-sabae Roemer. (Fig. 718.) Comanchic. 

 Beaks prominent ; ribs noded by concentric ridges. 

 Fredericksburg to Denison : Texas, Oklahoma. 



463. P. papyracea Meek and Hayden. Cretacic. 

 Beaks depressed, small, incurved. Surface of each valve marked 



