PLATE LX. 

 Gkammysia alveata. 



I'agc 3T0. 

 See Plate 57. 

 Fip. 1. The left side of a specimen retaining' both valves. 



Hamilton group. Madison. Co., N. Y. 

 V\g». 2-4. Left side, antei-ior and canlinal views of a specimen retaining its natural i>i-(>iioi-ti<)ns. 



Hamilton group. SclioTmrie Co., N. T. 

 Fig. 5. Cardinal view of a specimen which is vertically compressed. 

 Fig. 6. The right side of a specimen pi-eserving nearly the normal fonn. 



Hamilton group. Madison Co., N. Y. 

 Fig. 7. The cardinal area of a left valve. 



Hamilton group. Otsego Co., N. Y. 

 Fig. 8. A left valve preserving the normal form. 



Hamilton group. Madison, Co., N. Y. 

 Figs. 9, 10. Left side and anterior end of a large individual with sharp and distinct C(mcentnc fold 



Hamilton group. Schoharie Co., N. Y. 

 Fig. 11. The left side of a compressed specimen fig. 1 of plate 57. 



