PLATE XVII—Continued 
Pterinopecten spondylus. 
Page 65. 
Fig. 16. The interior of a left valve showing the spinous processes of the rays projecting from the pallial 
-margin, enlarged to two diameters. 
Hamilton group. Canandaigua lake, JSf. F. 
Pterinopecten conspectus. 
Page 66. 
Fig. 17. The exterior of an imperfect right valve as obtained from a g-utta-percha cast of the natural mould. 
Hamilton group. Skaneateles lake, JST. Y. 
Fig. 18. An exfoliated left valve. 
Hamilton group. Skaneateles lake, N. Y. 
Fig. 20. A specimen preserving the fine intermediate rays of the test. 
Hamilton group. Darien, Grehesee Co., N. Y. 
Fig. 21. A left valve with the test removed. The ear is represented as too oblique in the figure. 
Hamilton group. Skaneateles lake, N. Y. 
Pterinopecten intermedium. 
Page 68. 
See Plate 83. 
Fig. 19. A left valve enlarged to two diameters. 
Hamilton group. Cayuga lake, iV. F. 
Pterinopecten filitextus. 
Page 67. 
See Plate 82. 
Fig-. 22. A right valve preserving the test and showing the form of this valve. 
Hamilton group. From a boulder, Pine Valley, Chemung Co., N. Y. 
Actinopteria SUBDECUSSATA. 
Page no. 
See Plate 19. 
Fig-. 23. A small left valve. 
Fig. 25. A somewhat larger example. 
Fig. 26. An individual of medium size showing the form and surface markings. 
Fig-. 27. A left valve, a large portion of which is bx-oken away, showing the intei'ior of the right valve. 
Fig. 29. A lai-ge left valve. 
Fig. 30. A i-ight valve showing a gi-eater extent of the wing than in the opposite valve. 
Fig-. 31. A specimen of medium size, showing the interior of the left valve occupied by a portion of the 
right, and repi-esenting the diffei-ence in the strength of the sui'face max-kings on the two 
valves. 
Hamilton gi-oup. All from Canandaigua lake, except fig. 29 which is from Bellona, 
Yates Co., N. F. 
Actinopteria decussata. 
Page 111. 
' See Plates 18, 20 and 84. 
Fig. 24. A small left valve. 
Haixiilton group. Dresden, Yates Co., N. Y. 
Fig. 28. A lai-ge left valve with the test removed,- showixig the usual form of the shell. 
Hamilton gi-oup. Canandaigua lake, N. Y. 
