PELECYPODA—PRIONODESMACEA. 



493 



Hamilton : New York. 

 358. P. vertumnus Hall. (Fig. 661, a.) Devonic. 



Depressed-convex. Surface marked with irregular, alternating, 

 flexuous and flattened rays, crossed by sharp concentric striae. 



Hamilton : New York. 



Fig. 661. a, Pterinopecten vertumnus, left valve; b, P. suborbicularis ; c, P. 

 intermedins ; d, P. exfoliatus ; e, P. dispandus, right valve; f, g, P. undosus, right 

 and left valves. ( Pal. N. Y., V. ) 



359. P. undosus Hall. (Fig. 661,/, g.) Devonic. 

 Hinge line less than length of shell below. Valves depressed- 

 convex. Surface marked with many rays crossed by lamellose 

 growth lines and by 3-10 strong concentric undulations. 



Onondaga and Hamilton of New York. 



360. P. dispandus Hall. (Fig. 661, e.) Devonic. 

 Rays prominent, alternating with irregular finer ones, those of 



right valve bifurcate. Rays crossed by strong concentric growth 

 lines. Ear with fold. 



