PLATE LIV. 



GkaMMYSIA BI8ULCATA. 



Page 369. 



See Plates 56, 93. 



Fi(p8. 1-5. Young and medium-sized specimens pi-esenting the usual charactei-s of this fossil. 



Figf. 6. A left valve in which the stronger folds ai-e obsolete, pi-esenting characters which are partially 



shown in figs. 4 and 5. 

 Kg. 7. The left side of a large individual preserving the usual characters. 



Hamilton group. Madison Co., N. Y. 

 Figs. 8, 9. Left side and ant«Hor view of a partial cast preserving the natural form. 



Hamilton group. Madison Co., iV". Y. 

 Fig. 10. A specimen preserving the two valves in conjunction. 

 Fig. 11. The right side of a specimen which has been vertically compressed. 



Hamilton grouj). Madison Co., N. Y. 

 Fig. 12. The right side of a flattened specimen showing the valves retained in conjunction by the hinge 



ligament. 

 Fig. 13. The left side of a smaller individual. 



Hamilton group. Fultonham, Schoharie Co., N. Y. 

 Kg. 14. A specimen preserving the two valves in conjunction. 



Hamilton group. Bear's gulf, Schoharie Co., N. Y. 

 Fig. 15. An unusually large individual preserving the two valves in conjunction with the ligament partially 

 preserved. 



Hamilton group, ffeneseo, Livingston Co., N. Y. 

 Fig. 16. A specimen preserving Ixjth valves and having an unusually rotund form. See fig. 1 of plate 56. 

 Hamilton group. FUUmham, Schoharie Co., N. Y. 



