PLATE LXXXI—Continued. 
Aviculopecten TENUIS. 
Page 39. 
See Plate 7. 
Pig. 6. The left valve represented on pi. 7, fig. 28, redrawn to show the true form and ornamentation, 
with the pallial line and muscular impression. 
Chemung group. Near Salamanca, N. Y. 
Aviculopecten insignis. 
Page 34. 
See Plates 1 and 3. 
Fig. 7. A left valve preserving the form and proportions in greater perfection than shown on the previous 
plates. Hamilton group. Stafford, Genesee Co., N- Y. 
Aviculopecten bellus. 
Page 35. 
See Plate 2. 
Fig. 8. A right valve, X 2. 
Aviculopecten duplicatus. 
Page 17. 
See Plate 7. 
Fig. 9. A left valve showing the coarse radii on the pallial margin. 
Chemung group. Mansfield, Pa. 
Fig. 10. An entire right valve; : ! 
Chemung group. Mansfield, Pa. 
Aviculopecten rugasstriatus. 
Page 15. 
See Plate 7. 
Fig. 11. A right valve preserving the surface characters with considerable perfection. 
Chemung group. Rockville, N. Y. 
Fig. 12. Several of the radii, of the preceding specimen, enlarged two diameters to show the changes in 
surface ornamentation from the beak to the base. 
Aviculopecten princeps. 
Page 1. 
See Plates 1, 5, 6 and 24. 
Fig. 13. A right valve showing the pallial line and muscular impression. 
Hamilton group. Ludlowville, N. Y. 
Fig. 14. A specimen with a portion of the left valve removed showing the interior of the right valve and 
the difference in size between the right and left valves. 
Hamilton group. Muttonville, Ontano Co., N. Y. 
Fig. 15. A left valve as preserved in limestone. 
Hamilton group. Delaware, Ohio. 
Fig. 16. A specimen preserved in a soft shale showing strong regular concentric striae. 
Hamilton group. Livingston Co., N. Y. 
Fig. 17. An individual vertically imbedded in the shales showing the effects of compression and distortion. 
Hamilton group. N. Y. 
