PLATE LI. 
Figs. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Macrodon Hamiltonee. 
Page 349. 
1-4. A series of right valves, showing gradation in size and some slight variation in form. 
5. A specimen preserving the two valves in conjunction with the test mainly removed. 
Hamilton group. Shore of Canandaigua lake, N. Y. 
6 . A left valve enlarged to two diameters. 
Hamilton group. Shore of Skaneateles lake, N. Y. 
7. A similar form from the Waverly group of Bedford, Ohio. 
9. A cardinal view of a cast. 
Hamilton group. Shore of Cayuga lake, IV. Y. 
10. A left valve of an unusually large individual. 
Hamilton group. Near Cumberland, Md. 
Macrodon ovatus. 
Page 351. 
See Plate 93. • 
8 . A left valve, natural size. 
Waverly group. Granville, Ohio. 
Macrodon Chemungensis. 
Page 350. 
11. A cast of a small left valve. 
Chemung group. Near Elmira, N. Y. 
12. A large individual. 
Chemung group. Near Meadville, Pa. 
13. A right valve. 
Chemung group. Near Elmira, N. Y. 
14. A characteristic left valve. 
Chemung group. Near Elmira, N. Y. 
15. A large left valve. 
Chemung group. Near Elmira, N. Y. 
16. The left side of a cast with the umbo cut away to show the hinge characters, enlarged. 
Chemung group. Near Meadville, Pa. 
