286 



PLATE XI 



Page 



Figs. 1, 2. Parallelodon obsoletus (Meek and Worthen) 209 



Upper Pottsville (McArthur)?: Hocking County, Carbon 



Hill. 



Fig. 1. Right valve, slightly enlarged. 

 Fig. 2. Left valve, slightly enlarged. 



Figs. 3, 4. Parallelodon sangamonensis (Meek and Worthen) 210 



Lower Mercer limestone: Perry County, Somerset, Lo- 

 cality 35. 



Fig. 3. Right valve. Hyde collection 824. 

 Fig. 4. Left valve. Hyde collection 825. 



Figs. 5, 6. Myalina pernaformis (Cox) var 218 



Harrison ore: Jackson County, Hamilton Township, 



Locality 1. 



Fig. 5. Internal cast of left valve. 

 Fig. 6. Internal cast of a portion of a right valve. 



Figs. 7 to 9. Myalina pernaformis (Cox) 217 



Boggs member: Muskingum County, near Hope well P. O., 



Locality 26. 

 Left valves of three specimens. 



Figs. 10 to 12. Myalina recurvirostris var. sinuosa n. var 219 



Lower Mercer limestone: Muskingum County, near Adams 



Mills, Locality 42. 



Fig. 10. Left valve of a large specimen showing the ex- 

 tended hinge line. 



Fig. 11. Left valve of a smaller individual. 

 Fig. 12. Interior of left valve showing the recurved beak. 



Fig. 13. Myalina swallovi McChesney 219 



Lower Mercer member: Holmes County, Millersburg, 



Locality 57. 

 Left valve. 



Fig. 14. Cypricardinia ? carbonaria Meek 244 



Lower Mercer limestone: Licking County, Bald Knob, 



Locality 46. 

 Right valve. 



