I'LATE I.XXIX— Contiuueil. 



Genus ORISKANIA, gen. nov. 



Page '205. 



Oriskania navicella, sp. nov. 



Pigs. 25-27. Dorsal, profile and \entral viows of the exterior ; ■■showing- the elongate form and plano-convex 

 contour of the specie.s. 



Oriskany sandstone. Hondaitt, Neio York. 



Genus ROMINGERLNA, gkn. nov. 



I'age 2().). 



Romingerina Julia, A. Wiiichell. 



Fig. 28. Dorsal view of a large internal cast ; showing the form of the shell and the impression of the 



divided hinge-jilate, X 2. 

 Figs. 29, 30. Dorsal and profile views of a smaller internal cast ; showing the conv'exity of lioth valves. X 2. 

 Marshall group. Pointe aux Barques, Michigan. 



Genus CRYPTONELLA, Hall. 



I'age -2^6. 



Crvptonella (?) iNCONSTANS, HciTick. 



Figs. 31, 32. Dorsal and ventral views of a .small internal cast ; showing the form of the shell and muscular 

 mai-kings. 



Wa\erly group. Medina county, Ohio. 



Genus BEECHERIA, gen. nov. 



I'age 300. 



Beecheria D.4VIDSONI, iiom. nov. 



Figs. 33, 34. Doi'sal and profile views of an average si)ecimen. 

 Fig. 35. Dor.sal view of a more elongate shell. 



Fig. 36. The internal cardinal structure exposeil by the remo\al of a portion of the pedicle-vahe ; show- 

 ing the absence of dental plates in the valve, and the structure of the loop. X 3. 

 Carboniferous limestone. Windsor, Noin Scotia. 



Genus HARTTINA, oen. nov. 



Page i:n. 



Harttina Anna, Hartt. 



Figs. 37-30. Dorsal, profile and venti'al views of a well-jireserved example ; .showing the snbplano-convex 

 contour of the valves. 



Carboniferous limestone. Windsor, Nova Scotia. 



Genus CENTRONELLA, Billing-s. 



Page -26.5. 



Centronella (?) navicella, Hall. 



Figs. 40-42. Dorsal, profile and ventral views of the original example, which is referred with doubt to this 

 genus. 



Uliper Devonian. Rockford, Iowa. 



