Pig. 1. 
Pig. '2. 
Fig. 3. 
Fig. 4. 
Fig. 5. 
Fig. 6. 
Fig. 7. 
Fig. 8. 
Fig. 9. 
Fig. 10. 
Fig. 11. 
Fig. 12. 
Fig. 14, 
Fig. 15. 
Fig. 16. 
Fig. 17. 
Figs. 18, 
Fig. 13. 
Fig. 20. 
PLATE VII. 
Aviculopecten duplicatus. 
Page 17. 
See Plate 81. 
An imperfect right valve. 
Chemung group. Hobbieville, N. Y. 
A left valve, which shows the prevailing character of the species in having the anterior side longer 
and more extended than the posterior. The original of the species. 
Chemung group. Philipsburg, Alleghany Co., N. Y. 
A somewhat larger left valve. 
Chemung group. Rockville, Alleghany Co., N. Y. 
The surface of a specimen enlarged to three diameters. 
Chemung group. Rockville, N. Y. 
A left valve. The outline of the figure is somewhat too high and too short, and bears an unnatural 
resemblance to the succeeding species. 
Chemung group. Rockville, N. Y. 
A right valve. The figure represents the body, too short, the striae too sharp and the beak too 
obtuse. 
Chemung group. East Randolph, N. Y. 
A small left valve. 
Chemung group. Rockville , N. Y. 
Aviculopecten rug^striatus. 
Page 15. 
See Plate 81. 
A small left valve nearly entire, showing - the usual form of the species. t 
Chemung group. Philipsburg, N. Y. 
A larger left valve of similar character to the preceding. 
An enlargement of the surface, showing the character of the ornamentation. 
A nearly entire right valve. ] 
Chemuiig group. Rockville, N. Y. 
AviCyLOPECTEN CANCELLATUS. 
Page 18. 
A right valve, showing the usual form and proportions. 
Chemung group. Philipsburg, N. Y. 
A right valve preserving the ears and surface markings in a very perfect condition. 
Chemung group. Conewango, Cattaraugus Co., N. Y. 
An enlargement of the preceding specimen to two diameters. 
The interior impression of a right valve, with radii partially preserved. 
Chemung group. Westfield, N. Y. 
An enlargement of a small right valve to two diameters. 
Chemung group. Conewango, N. Y. 
19. A right valve, natural size and enlarged. The specimen is somewhat distorted from pressure, 
and does not represent the normal form of the shell. 
Chemung group. Rockville, N. Y. 
Aviculopecten Itts. 
The right valve described. 
Chemung group. 
Page 20. 
Conewango, N. Y. 
Aviculopecten squama. 
Page 27. 
A right valve enlarged to two diameters, showing the form, ears and surface markings. 
Chemung group. Philipsburg, IV. Y. 
