PLATE LXXIII. 



Page. 



Cuoullaia liar/uei Meek G18 



Fig. 1. Left valve slightly flattened and showing both surface, sculpture and hinge impres- 

 sion; enlarged 2 diameters. 



Triijonia elegaiilissima Meek 619 



Fig. 2. Left valve; enlarged 1A diameters. 



Asiarte meeki n. sp 620 



Fig. 3. Eight valve from Cinnabar Mountain ; enlarged li diameters. 



4. Left valve from lower canyon of Yellowstone; enlarged li diameters (United States 



National Museum, No. 12374). 



5. Elongate right valve, probably distorted by pressure, and showing impression of 



the creuulate interior margin; enlarged 2 diameters. 

 Tancredia ? knowltoni n. sp 621 



Fig. 6. Cast of right valve; enlarged 1A diameters. 

 Cyprhia i eiiinabarensis n. sp 621 



Figs. 7, 8. Two views of an internal cast, one of the types. 

 Cyprina ? iddingsi n. sp 622 



Fig. 9. Eight valve of the type. 

 Thracia f montanaensis (Meek)? 628 



Fig. 10. Eight valve, supposed to be Meek's original type; enlarged li diameters. 

 Cypricardia ? liaguei n. sp 623 



Figs. 11, 12. Two views of an average specimen, internal cast. 

 13. Eight valve of a large elongate specimen. 



644 



