PLATE Y. 
Pterinopecten Vertumnus. 
Page 71. 
See Plate 83. 
Figs. 1-6. Left valves of various sizes, showing slight variations in outline, and considerable variation in 
the number and strength of the rays. 
Fig. 7. A small right valve. The byssal sinus is not represented sufficiently deep 
Fig, 8. A specimen preserving both valves, showing their comparative form and surface ornamentation. 
Hamilton group. Schoharie Co ., N. F. 
Avicui.opecten fasciculatus. 
Page 11. 
See Plate 81. 
Figs. 9, 10. Two small left valves. 
Hamilton group. Fultonliam, Schoharie Co., N. Y. 
Fig. 11. A left valve. Another figure of this specimen is given on plate 81, fig. 3, showing the concentric 
strife. 
Hamilton group. Castleton, Ontario Co., N. Y. 
Fig. 12. A left valve which is much produced posteriorly. The specimen is imperfect at the beak, and is 
restored in the figure. 
Hamilton group. Fultonham, Schoharie Co ., N. Y. 
Fig. 13. An imperfect left valve, showing strong fascicles of radiating striae. 
Figs. 14, 15. Two large left valves, with simple thread-like striae ornamenting the surface. 
Fig - . 16. A small right valve of this species. 
Hamilton group. Schoharie Co., N. Y. 
Fig. 17. A left valve presenting great irregularities in the radii, due to accident and intermittent growth. 
Hamilton group. Cazenoma, N. Y. 
Aviculopecten princeps. 
Page 1. 
See Plates 1, 6, 24 and 81. 
Fig. 18. A small left valve preserving a portion of the test. 
Hamilton group. Canandaigua lake, N. Y. 
Fig. 19. A portion of the test enlarged, showing the surface ornamentation. 
Fig. 23. An imperfect left valve. 
Hamilton group. Western N. Y. 
Fig. 24. An entire and characteristic right valve. 
Hamilton group. Cazenovia, N. Y. 
Aviculopecten formio. 
Page 9. 
Fig. 20. An imperfect left valve of the species. The margins of both ears are represented as too concave 
in the figure. 
Hamilton group. Fioltonham, Schoharie Co., N. Y. 
Fig. 21. A smaller specimen retaining both valves. 
Hamilton group. Madison Co., N. Y. 
Aviculopecten 
Page 10. 
Fig. 22. A left valve preserving a nearly entire outline. 
Hamilton group. Schoharie Co., N. 
Phorcus. 
