PLATE LXVI 



PAGE 



Fig. 1. EATONIA SINUATA Hall 375 



Internal cast of ventral valve. Oriskany formation, Ridgely member, 

 Cumberland. (After Hall.) 



Figs. 2, 3. EATONIA HARTLEYI Schuchert n. sp 376 



Dorsal and side views. Oriskany formation, Ridgely member, Martin 

 Mountain, Allegany County. 



Fig. 4. RHYNCHONELLA ( ?) BIALVEATA Hall 377 



Dorsal view. X 2. New Scotland formation, New York. 



Figs. 5, 6. RENSSEL^RIA MUTABILIS (Hall) 378 



Dorsal and ventral views. Helderberg formation, Keyser member, 

 Cumberland. 



Figs. 7-9. RENSSEL^ERIA MUTABILIS VAR 378 



Ventral, dorsal, and side views. Helderberg formation, Keyser 

 member, Tonoloway. 



Figs. 10-12. RENSSEL^RIA SUBGLOBOSA Weller 379 



10. Ventral valve. 



11, 12. Ventral and side views of an average individual. 



Helderberg formation, Becraft member, Cherry Run, W. Va. 



Fig. 13. RENSSEL.ERIA SUBGLOBOSA VAR. AVUS Schuchert n. var 380 



Ventral valve, slightly distorted. Helderberg formation, Becraft 

 member, Cherry Run, W. Va. 



Fig. 14. RENSSEL^ERIA SUBGLOBOSA VAR, CRASSA Schuchert n. var 381 



Ventral valve showing the coarser striae. Helderberg formation, 

 Becraft member, Licking Creek, Pa. 



Figs. 15-17. RENSSEL^RIA CIRCULARIS Schuchert n. sp 381 



Ventral, dorsal, and side views. Oriskany formation, Ridgely mem- 

 ber, Cumberland. 



Figs. 18-24. RENSSEL^ERIA MARYLANDICA Hall 382 



18, 19. Dorsal and side views of a small specimen. 

 20, 21. Dorsal and side views of an average specimen. 



22. Interior of ventral valve. 



23. Interior of dorsal valve to show the large crural plates and the 



pointed brachidium which supports the fleshy arms. 



24. Median section of shell to show the various plates, thickening of 



the posterior region of the valves, and the position of the jugum. 

 Oriskany formation, Ridgely member, Cumberland. (After 

 Hall.) 



Fig. 25. RENSSEL.^RIA MARYLAXDICA VAR. SYMMETRICA Schuchert n. var. . 384 

 Dorsal view. Oriskany formation, Ridgely member, Cumberland. 



Figs. 26-28. RENSSEL^RIA KEYSERENSIS Swartz n. sp 384 



Ventral, dorsal, and side views of type. Helderberg formation, Keyser 

 member, % mile southwest of Rawlings. 



57 



