PLATE LXXVII— Continued. 



Genus RENSSEL^RIA, Hall. 



Pa^ 254. 

 ReNSSEL^ERIA CuMBERLANDIiE, Hall. 



FifC8. 23-25. Doi-sal, profile and ventral views of one of the original specimens j showing the form and pro- 

 portions of the shell, the marginal plication of the surface, the deltiilial plates and sharply de- 

 fine<l cardinal slopes. 



Oriskany sandstone. Oiimberland, Maryland. 



Ren88el.£RIA intermedia, Hall. 



Kg. 26. Dorsal view of the exterior ; showing the form and character of plication. 

 Figs. 27, 28. Profile views of different individuals ; showing the convexity of the valves. 

 Criskany sandstone. Ouinberland, Maryland. 



