PLATE LXXXIII. 
Pterinopecten regularis. 
Page 70. . 
Fig. 1. A left valve showing the characteristic form and surface markings. 
Hamilton group. Livingston Co., N. Y. 
Pterinopecten Vertumnus. 
Page 71. 
See Plate 5. 
Fig. 2. A small specimen preserving the left valve entire and a portion of the right valve. 
Hamilton group. Onondaga Co., N. Y. 
Fig. 3. A left valve to show the characters of the surface ornamentation. 
Hamilton group. Skaneateles lake, N. Y. 
Pterinopecten intermedius. 
See Plate 17. 
Fig. 4. A left valve wholly denuded of the test. , 
Hamilton group. Cayuga lake, N. Y. 
Fig. 5. A left valve as obtained from an impression of the exterior in the matrix, showing- the form and 
surface markings. 
Hamilton group. Cayuga lake, N. Y. 
