PLATE V. 



Ptkrinopecten Vertumnus. 



Page 71. 



See Plate 83. 



Fiffs. 1-6. Lpft valves of various sizes, showing slight variations in outline, anil considerable variation in 



thp numbpr and strength of the rays. 

 Fig. 7. A small right valve. The l)ys.«al .sinus is not represented sufficiently deep 



Fig. 8. A .snei-imen pre.serviiig both valves, showing their comparative form ami surfai-e ornamentation. 

 Hamilton grouji. f^chohark Co., iV. Y. 



AviCDT,OPECTEX FASCICULATUS. 

 Page 11. ' 

 See Plate 81. 

 Figs. 9, 10. Two small left valves. 



Hamilton group. Pultonham. Svhoharie Co , N. Y. 

 Fig. 1 1. A left valve. Another figure of this specimen is given on plate 81, fig. 3, showing the concentric 

 striiP. 



Hamilton grouji. CoxtMon. Ontario Co., X Y. 

 Fig. 12. A left valve which is much produceil ]>o.steriorly. The spi-eimeM is imi>ei-feit at the bi^ak. and is 

 restored in the figure. 



Hamilton group. Fulto^ihaiii, Schoharie Co.. N. Y. 

 Fig. 13 An imperfect left valve, showing sti-ong faseicles of I'adiating .stria'. 

 Figs. 14, 15. Two large left valve.s, with simple thread-like stria- ornamenting the sui-face. 

 Fig. IK. A small light valve of this species 



Hamilton group. Schoharie Co.. N. Y. 

 Fig. 17. A left valve presenting gi-eat irregularities in the radii, due to accident and intei'mittent growth. 

 Hamilton group. Cazemmla, N. Y. 



AVICULOPECTEN PRINCEPS. 



Page 1. 

 See Plates 1, 6. 24 anil 81. 

 F"ig. 18. A small left vahe preserving a portion of the test. 



Hamilton gronp. Canundaigtia lake. N. Y. 

 Fig. 19. A portion of the test enlarged, showing the surface ornamentation. 

 Fig. 23. An irapei-fect left valve. 



Hamilton group. Western iV. Y. 

 Fig. 24. .\n entire and characteristic right valve. 



Hamilton grouii. Cazenavia, N. 1'. 



AVICCLOPECTEN FORMIO. 



Page 9. 

 Fig. 20. An iin]ierfeit left valve of the .species. The margins of both ears are represented as too concave 

 in the figure. 



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

 Fig. 21. .\ .smaller s|lecinl(^n retaining both valves. 



Hamilton gTou]i. Madison Co., N. Y. 



AviCULOPECTEN PhORCUS. 



I'ngc 10. 

 Fig. 22. A left valve preserving a nearly entire outline. 



Hamilton grou)i. Sctwharie Co., iV. Y. 



