PLATE LXVIII 



PAGE 



Figs. 1-3. ATRYPA ? BICOXVEXA Maynard n. sp 393 



1, 2. Ventral and dorsal views. Keyser, W. Va. 



3. Dorsal view of another example. Cash Valley, Cumberland. 



Helderberg formation, Keyser member. 



Figs. 4-6. ATKYPINA IMBRICATA (Hall) 394 



4, 5. Ventral and dorsal views. 

 6. Dorsal view. X 3. 



New Scotland formation. New York. 



' 4 f 

 fc^a^ovnE ^*^ 



Figs. 7, 8. SPIRIFER' MAdROPLEURUs (Conrad) 396 



Dorsal and ventral valves. Helderberg formation, New Scotland mem- 

 ber, Corriganville. 



Figs. 9-16. SPIRIFER CUMBERLANDI.E Hall 398 



9-11. Dorsal, ventral, and side views of a small specimen. 

 12-14. Same views of an average specimen. 

 15, 16. Interior of ventral and dorsal valves. 



Oriskany formation, Ridgely member, Cumberland. (After 

 Hall.) 



Figs. 17-22. SPIRIFER MODESTUS Hall 399 



17, 18. Dorsal and front view. 



19-21. Dorsal, ventral, and side views of a larger individual. 



22. Interior of ventral valve. 



Helderberg formation, Keyser member, Cumberland. (After 

 Hall.) 



Figs. 23, 24. SPIRIFER MODESTU s VAR. PLICATUS Maynard n. var 400 



Dorsal and ventral views of type. Helderberg formation, Keyser 

 member, Keyser, W. Va. 



Figs. 25-29. SPIRIFER OCTOCOSTATUS Hall 401 



25-28. Ventral, dorsal, side, and cardinal views. 

 29. Interior of ventral valve. 



Helderberg formation, Keyser member, Cumberland. (After 

 Hall.) 



Figs. 30, 31. SPIRIFER PAUCICOSTATUS Schuchert n. sp 402 



Internal casts of dorsal and ventral valves. X 3. Oriskany forma- 

 tion, Shriver member, Cash Valley. 



Figs. 32, 33. SPIRIFER VAXVXEMI Hall 403 



Ventral and dorsal views. Manlius formation, New York. 



Figs. 34, 35. SPIRIFER VAXUXEMI VAR. PROGXOSTICA Schuchert n. var 403 



Ventral and dorsal views. Helderberg formation, Keyser member, 

 % mile southwest of Rawlings. 



