PLATE XXXI. 



MvTiL.iitCA (Pletiiomvtilis) oviformis. 



Page "2.55. 

 See Plate 87. 



.\ lift valve of a young' shell of elongate form. 



Hamilton group. Cayuga lake, N. Y. , 



2. A left valve of the ordiiiai-y size, .showing the sti-iateil hinge-area and three posterior teeth on the 

 wing whii-h are not sufficiently marked in the lithography. 

 Hamilton group. Cayuga lake, X. If. 

 A i-ight valve showing the strong ligamental area. 

 A more elongate form with attenuate beak. 



Hamilton group. York Centre, Hvingslon Co., N. T. 

 Fig. ."). Till' anterior .side of a compressed .speeimon presei-ving the valves in contact at the hinge, but 

 widely parted below. 



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

 Fig. G. A large i-ight valve widened below by compression. 



Hamilton group. Seneca lake, N. Y. 

 Fig. 7. A ca.st of a .small elongate right valve. The beak has been removed to show the ligamental ai-ea : 

 the three oblique lateral teeth are seen on the post-£ardinal .angle. 

 Hamilton group. Canandaigua lake, N. Y. 

 Fig. 8. A large, broad right valve showing an unusually short hinge-area. 

 Hamilton group. Belloiia, Yates Co., N'. Y. 



GOSSELETTIA TRIQUETRA. 



rage 2ti5. 

 See Plate 87. 

 Fig. 9. A view of the left valve of a young individual of this species. 

 Fig. 10. The right side of a vej'y ventricose si^ecimen preserving the natural form. Supposed to be the 



original specimen. 

 Figs. 11, 18. 14. The Left, cardinal and posterior ^•iews of a specimen preserWng the natural convexity 

 and showing the posterior teeth of the left valve. 

 Hamilton group. Onondaga Co., N. Y. 

 Fig. 12. The anterior side of a similar specimen showing the anterior muscular impressions. 



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

 Fig. 15. A partial cast of a left valve. The beak has been removed to show the strong anterior teeth and 

 anterior muscular impression. 



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

 Fig. ] li. A large left valvi? preser\ing the surface markings and the ligamental area. 



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

 Fig. 17. A large right valve. 



Hamilton group. Madison Co., N. Y. 



