PLATE LI. 



Mackodon Hamiltonkk. l, 



Pa^ 349. 



Figs. 1-4. A series of ri^t valves, showing gradation in size and some slight variation in form. 

 Fig. 5. A specimen preserving the two valves in conjunction with the test mainly removed. 



Hamilton group. Shore of Oanandaigua lake, N. Y. 

 Fig. 6. A left valve enlarged to two diametei-s. 



Hamilton group. Shore of SkaneaUies lake, N. Y. 

 Fig. 7. A similar form from the Waverly group of Bedftrrd, Ohio. 

 Fig. 9. A cardinal view of a cast. 



Hamilton group. Shore of Caynga lake, N. Y. 

 Fig. 10. A left valve of an unusually large individual. , ,'.j 



Hamilton group. Near Cumberland, Md. ,,j-.| 



Macrodon ovatus. 



Page 381. 

 See Plate 03. 

 Fig. 8. A loft valve, natural size. 



Wavei'ly group. Cfrantdltf, Ohio, 



M.\CRODON ChEMUNGEN8I«. 



I'ajte CiO. 

 Pig. 11. A cast of a small left valve. 



CheraOng group. Near Uimira, N. Y. 

 Fig. 12. A large individual. 



Chemung group. Near Meadville, Pa. 

 Fig. 13. A right valve. 



Chemung group. Near Elmira, N. Y. 

 Fig. 14. A characteristic left valve. 



Chemung group. Near Elmira, N. Y. .>iJ>l 



Fig. l.*). A large left valve. 



Chemung group. Near Elmira, N. Y. 

 Fig. 16. The left side of a cast with the umbo cut away to show the hinge; rliaracters. enlarged. 



Chemung group. Near MeadvUU, Pa. 



m- 



