49Q 



NORTH AMERICAN INDEX FOSSILS. 



Upper Carbonic of Utah, Wyoming and elsewhere in west. 

 346. A. occidaneus Meek. (Fig. 654, b.) Carbonic. 



Fig. 653. Aviculopecten interlineatus. (Kan. Pal., VI/II. ) 



FlG. 654. Aviculopecten curtocardinalis, X 2 O e ft) > A. occidaneus. (After Hall 

 and Whitfield, and after Meek.) 



Slightly more oblique than preceding ; striae alternating, 2 to 4 

 smaller between larger. 



Occurs with preceding. 

 347. A. parvulus Hall and Whitf. (Fig. 655, a.) Carbonic. 



Fig. 655. Aviculopecten parvulus, X 3 U e ft) 

 (After Hall and Whitfield. ) 



A. weberensis. 



More elongate and with larger ears than preceding, large ribs 

 sharp and strong, smaller generally only one. 



Occurs with the preceding. 

 348. A. weberensis Hall and Whitf. (Fig. 655, b.) Carbonic. 



Ears more pronounced than in preceding, 

 plications smaller, several near front only. 



Occurs with preceding generally. 

 349. A. occidentalis (Shumard). (Fig. 

 656.) Carbonic-Permic. 



Both valves crossed by distinct radiating 

 ribs, those of the left valve the more prom- 

 inent. Whole valve crossed by concentric 

 Fig. GtfTJviculopecten g rowlh lines - Ears lar S e > umbo rectang- 



occidentalis, left valve. (Ind. ular to acute. 



Surv Common in Carbonic rocks of the United 



States from Pennsylvania and Kentucky, westward and southward 



