PLATE XII. 



The figures on the uppei- half ot~ the plate illustrate the fauna of the Coal Measure Cherts 

 of Hocking County, Ohio. 



PAGE. 



Figs. 1-2. Discina Meekana Whitf. 488 



1. View of a lower valve from th ; black chert bed-:. 



2. View of a more nearly entire valve from Flint Ridge. See lower left corner of plate. 



Figs. 3-6. Spirifera ( Martinia ) lineaTa Martin 488 



3. 4 and 5. Dorsal, ventral and front views of an internal cast from the yellow cherts. 

 6. View, enlarged to two diameters, of a partial cast from the black chert The speci- 

 men shows the s;tte where the shell is retained. 



Figs. 7-9. Athyris subtieita Hall 488 



7-9. Dorsal, ventral and profile views of an internal cast of this species. 

 Figs. 10-11. AvicUEOPECTEN INTERLINEATUS M.. and W 489 



10 and 11. Views of an imperfect left and right valves as obtained by gutta-percha 



from the casts in the yellow cherts. 



Figs. 12-14. Naticopsis Ortoni Whitf 489 



12 and 13 Front and back views enlarged to two diameters, ol a specimen from the 

 yel ow cherts. 



11 Diagram of the aperture as shown by the breaking: of the shell back of the aperture, 



showing the thickened shell. 



Figs. 15-17. Anthracopupa Ohioensis Whitf -191 



15. View, greatly enlarged, of the back of the shell. 



Hi and 17. Similar views of the front and side showing the apertural features and 

 thickened lip. 



Figs. 18-19. Spirorbis anthracosia Whitf 492 



IS and 19. Upper and lateral views, greatly enlarged, of a specimen of the prevailing 

 form. 



Fig. 20. Nautieus Ortoni Whitf. 48d 



L'O. Lateral view of the specimen described showing the characters of the shell. 



