PLATE II. 



PAGE. 



Ptekinea demissa 78 



Fig. 1. View of a left valve, from Cincinnati, Ohio, showing the general features of the species. The 

 figure is slightly restored on the posterior wing. 



Ambonychia radiata 79 



Pig. 2. View of the left side of a small but quite perfect and characteristic specimen of the species. 



SeDGWICKIA ? DIVAEICATA 89 



Fig. 3. View of the left side of the specimen described, showing the general form and surface- 

 markiusrs. 



Orthodesma contracta 96 



Fig. 4. View of the left side of the typical specimen used in the original description of the species, 

 showing the plications of the CHrdinal slope. 

 5. View of another and somewhat ditterently formed individual referred to the species, obtained 

 near Waynesville, Ohio. 



Orthodesma curvata 95 



Fig. 6. View of the left side of a specimen, showing the general features of the species. 



Orthodesma recta 94 



Fig. 7. View of the right side of a small specimen. 



8. View of a larger individual, showing the general features of the species. 



Cuneamya Miamiensis 91 



Fig. 9. Cardinal view of a well-maiked specimen of the species. 

 10. View of the right side of the same individual. 



Grammysia neglecta 92 



Fig. 11. View of a specimen supposed to be the form described by Mr. Meek, from a very imperfect 

 individual, under the name Sedgwickia ? (Grammysia f) neglecta, introduced for comparison 

 with figs. 9 and 10. 



Cuneamya scAPHA , 92 



Fig. 12. View of the left side of a specimen of moderate size, and slightly compressed, but showing 

 the featiu-es of the species. 



MODIOLOPSIS TRUXCATA 86 



Fig. 13. View of the right valve of one of the original specimens figured in the Pal. Jf. T., Vol. I. 

 The specimen is from Cincinnati, Ohio. 



MODIOLOPSIS CiNCINNATIENSIS 88 



Fig. 14. View of a small specimen, showing the general form and convexity of the species. 

 15. View of a larger specimen, showing stronger undulations of growth. 



MODIOLOPSIS PHOLADIFORMIS 85 



Fig. 16. View of a well-marked specimen of this species, showing the plications of the surface. 



MODIOLOPSIS MODIOLARIS 83 



Fig. 17. View of an impression of the interior of a right valve of this species, from Cincinnati, Ohio, 

 showing the filling of the tooth cavity just above the anterior muscular impression. 



MODIOLOPSIS CONCENTRICA 86 



Fig. 18. View of a small specimen retaining both valves, and showing the surface-markings quite 

 well preserved. 



