PLATK LXXIX— Conllnuod. 



Gbmus ORISKANIA, gen. nov. 



Pago -id!). 



Oriskama navicella, sp. nov. 



Figs. 96-C7. Doreal, profile and ventral views of the exterior ; Kbowing the elong'ate form and plano-convex 

 contour of the species. 



Oriskany sandHtone. Handout, New York. 



Genus ROMINGERINA, gkn. nov. 



I'age 2lio. 



ROMINOERINA JULIA, A. Wlllchell. 



Fi^. 28. Dorsal view of a large internal cn«t ; showing the form of the shell and the impression of the 



divided hinge-plate, X 2. 

 Figs. 29, 80. Dorsal and profile views of a smaller internal cast ; showing the convexity of both valves. X 3. 

 Marshall group. PoitUe aux Barques, Michigan. 



Genus CRYFrONELLA, Hall. 



Page 2S6. 



CUYPrONELLA (?) INCONSTAN8, HeiTJck. 



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

 markings. 



Waverly group. Medina county, Ohio. 



Genus BEECHERIA, gen. nov. 



I'age 300. 



Beecheria Davidsoni, iiom. nov. 



Figs. 33, 34. Dorsal ami profile views of an average specimen. 

 Fig. 36. Dorsal view of a more elongate shell. 



Fig. 86. The internal cai-dinal structure exijosed by the removal of a portion of the pedicle-valve ; show- 

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

 Carboniferous limestone. Windsor, Nova Scotia. 



Genus HARTTINA, gen. nov. 



Page 2»2. 



Hakttina Anna, Hartt. 



Figs. 87-39. Dorsal, profile and ventral views of a well-preserved example ; showing the subplano-convex 

 contour of the valves. 



Carboniferous limestoue. WiiulMor, Num fivotia. 



Genus CENTRONELLA, Billings. 



Page iia. 



CeNTRONELLA (?) NAVICELLA, Hall. 



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

 genus. 



Upper Devonian . Hocltford, Iowa. 



