PLATE 11. 
Page 
Figs. 1-3. Strophodonta alveata. 81 
1. The interior of a dorsal valve as obtained from a cast in the Schoharie grit. 
2. The cast of a ventral valve. 
3- A smaller ventral valve of the same species. 
Figs. 4-10. Strophodonta callosa. 82 
. 4. Interior of a dorsal valve, from an impression in the natural mould, showing muscular impres¬ 
sions and cardinal process; enlarged to two diameters. 
6, 7. Casts of ventral valves, natural size. 
8. Interior of the dorsal valve, from an impression in the natural mould, showing muscular 
impressions, cardinal prpcess, and the crenulated hinge line; enlarged to two diameters. 
9, 10. Cardinal and ventral views of a cast of a ventral valve, showing the muscular impres¬ 
sions very distinctly; enlarged to two diameters. 
Figs. 5, 11. Strophodonta parva. 85 
5. Impression of a dorsal valve of this species. 
11. Cast of a ventral valve, enlarged to two diameters, showing muscular impressions and the 
crenulated hinge. 
Figs. 12, 13, 18- 21. Strophodonta crebristriata. 86 
12. Exterior of a small ventral valve. 
13. Exterior of a smaller ventral valve, enlarged to two diameters. 
18, 19. Exterior and profile of a larger ventral valve. 
20. Enlargement of the surface striae. 
21. Exterior of a very large ventral valve. 
23. Interior of a dorsal valve, from an impression in the natural mould. Doubtfully referred 
to this species. 
« 
Figs. 14-17. Strophodonta demissa. 81 
14. View of a ventral valve taken from an impression left in the Schoharie grit by the decay of 
the shell. 
15. Internal cast of a ventral valve in the grit. 
16. Interior of a dorsal valve, showing the muscular impressions and cardinal process. 
17. Cast of the interior of a ventral valve, showing the muscular impressions in a very perfect 
manner. From the soft shales of the Hamilton group. 
Fig. 22. Strophodonta perplana. 92 
22. An impression of a ventral valve of this species. 
Figs. 24-31. Strophodonta inequiradiata... 87 
24, 25. Profile, and vertical view of a ventral valve with distant coarse stria. 
26. Yiew of a cast of a ventral valve showing a narrow muscular impression. 
27, 28. Front and cardinal views of a cast of a.ventral valve, showing muscular and vascular 
impressions in a very perfect manner. 
29. Cast of a large ventral valve. 
30, 31. Impressions of the exteriors of dorsal valves, showing sharp distant striae. 
