282 



PLATE IX 



Page 



Figs. 1 to 5. Marginifera muricata var. missouriensis Girty 184 



Upper Pottsville (McArthur)?: Hocking County, Carbon 

 Hill. 



Fig. 1. Dorsal valve. xl 



Figs. 2, 3. Ventral valves. xl| 



Lower Mercer limestone: Muskingum County, near White 

 Cottage, Locality 36. 



Fig. 4. Ventral valve. 



Fig. 5. Dorsal valve. 

 Figs. 6 to 10. Marginifera wabashensis (Norwood and Pratten) 185 



Lower Mercer limestone: Muskingum County, near White 

 Cottage, Locality 36. 



Figs. 6, 7, 8. Ventral valves of three specimens. xl| 



Fig. 9. Lateral view of Fig. 6 showing the normal con- 

 vexity of the species. 



Fig. 10. After Mark. Ventral valve. Conemaugh forma- 

 tion: Cambridge limestone, Norwich, Ohio. 

 Figs. 11,12. Spirifer cameratus Morton 188 



After Mark. Conemaugh formation: Cambridge lime- 

 stone, Langsville, Ohio. 



Fig. 11. Dorsal valve. 



Fig. 12. Ventral valve. 

 Figs. 13 to 20. Spirifer opimus Hall 188 



Upper Pottsville (McArthur)?: Hocking County, Carbon 



Hill. 



Figs. 13, 14, 15. Dorsal valves of three specimens. 



Figs. 16, 17, 18, 19, 20. Ventral valves of five specimens 



showing variations in form. 

 Figs. 21 to 25. Spirifer boonensis Swallow? 186 



Boggs limestone: Muskingum County, near Hopewell P. 

 O., Locality 18. 



Figs. 21, 22. Ventral valves. 



Fig. 23. Internal cast of ventral valve. 



Figs. 24, 25. Dorsal valves of two specimens. 

 Figs. 26,27. Squamularia perplexa (McChesney) 191 



Low^r Mercer limestone: Muskingum County, Blunt 

 Run, Locality 27. 



Fig. 26. Ventral valve. 



Fig. 27. Dorsal valve of same specimen. 

 Figs. 28, 29. Hustedia mormoni (Marcou) 192 



After Mark. Conemaugh formation: Ames limestone, 

 Steubenville, Ohio. 



Fig. 28. Dorsal valve. x2 



Fig. 29. Lateral view. x2 



