PELECYPODA—PRIONODESMA CEA . 



491 



to Utah and Arizona. Ranges from Lower Coal Measures to the 

 Upper and into Permic in Kansas and Texas. 

 350. A. germanus Miller and Faber. (Fig. 657.) Carb.-Permic. 

 Radiating ribs about 12, alternating with about the same num- 

 ber of shorter ribs, and all separated by wide, flattened spaces. 



Fig. 657. Aviculopecten germanus. (Kan. Pal., VI/II. 

 Fig. 658. Aviculopecten maccoyi. (Kan. Pal., VI/II.) 



Coal Measures : Kentucky, Kansas, Oklahoma. Permic : Kansas. 



351. A. maccoyi Meek and Hayden. (Fig. 658.) Car.-Permic. 

 Ribs 3 to 6, roughened by scale- like projections and separated 



by smaller striae. 



Coal Measures : Kansas, Oklahoma. Permic : Kansas. Also 

 Carbonic of New Mexico. 



352. A. vanvleeti Beede. (Fig. 659, c.) Permic. 



Fig. 659. a, 6, Acanthopecten carboniferus ; left and right valves. 

 c, Aviculopecten vanvleeti. (Kan. Sci. Bull. ) 



(Ind. Surv. ) 



Differs from A. maccoyi in larger size and in the larger rays 

 which are prominent only when half way down the shell. 



Upper Permic : Oklahoma (Whitehorse), Texas (Quarter- 

 master). 



