PLATE XXIV— Continued. 



Ptekinea (Vertumnia) reversa. 



Page 104. 



See Plate 84. 

 Fig. fi. A large right valve. Another figure of this specimen is given on plate S4, fig. 24. to show the 

 obsolescence of the rays on the wing. 



Chemung group. Elmira, N. Y. 

 Fig. 12. A specimen with the valves united along the hinge, showing the convex right valve and flat or 

 concave left \alve. 



Chemung group. Chemung river, Upper Narrows, N. Y. 



AviCULOPECTEX PRIXCEPS. 



Page 1. 



See Plates 1. 5, G and 81. 



Fi°\ 7. An enlargement, to two diameters, of the impression of the hinge, showing the striatums of the 



ligamental area. 



Hamilton group. Cast wroia, X. Y. 



Ltriopecten oymbalox. 



Page 47. 

 Fig. 8. A large, perfect left valve. The specimen shows a striated ligamental area. 

 Hamilton group. From a boul ler near Elmira, X. Y. 



I'terixea (Yertumxia) avis. 



Page 105. 

 Fig. 9. An imperfect right valve. 



Chemung group. Near Elmira, N. Y. 

 Fig. 11. A large, convex right valve. The figure should be restored at the cardinal angles to correspond 

 with tig. 13. 



Chemung group. Mansfield, Pa. 

 Fig. 13. A nearly entire left valve. The byssal sinus should be a little deeper than is represented. 

 Chemung group. Near Elmira. X r . Y. 



Pterixopectex suborbicularis. 



Page 80. 



See Plates 8 and 82. 

 Fig. 10. A view of a large and verj perfect left valve. The radii increase by interstitial addition and not 

 by bifurcation as is represented in the figure. 



Chemung group. Elm Valley, Alleghany Co.. N. 1". 



LlMOPTERA MACROPTERA. 



Page 246. 

 See Plates 26, 27, 28, 29 and 92. 



Fig. 14. A small right valve showing the form and surface ornamentation. 

 Hamilton group. Pratt's Falls, Onondaga Co., N. Y. 



AlXOCARDIUM ALTERXATUM, geil. et sp. 110V. 



Fig. 15. A view of the specimen enlarged to two diameters. The relations of this shell are not apparent. 



It has the as] t of a bivalve shell in the characters of the rays and the cardinal aurieulation, 



and somewhat resembles lliri-Aors and TRIGONILTJNA. With the present material it cannot 

 lie satisfactorily arranged with any known genus of molluscs. 

 Hamilton group. Cayuga lake, X. Y. 



