I'l.ATE XVII— Contitiueil 



Pterinopecten spondylus. 



Page Go. 

 Fif.'. 111. The interior of a left valve showing the spinous processes of tlie rays projecting' from tho pallial 

 niarg-in. enlarged to two diametei-s. 



, Hamilton group. CanandaigJM lake, N. T. 



Pterinopecten conspectus. 



Page 06. 

 Fig. 17. The exterior of an imperfect right valve as obtained from a gutta-percha cast of the natural mould. 



Hamilton group. Skancateles lake, N. T. 

 Fig. 1§. An exfoliated left valve. 



Hamilton group. Skaneateles lake, N. T. 

 Fig. 20. A specimen i)reserving the fine intermediate rays of the test. 



Hamilton group. Darien, Genenee Co., N. Y. 

 Fig. 21. A left valve with the test removed. The ear is represented as too oblique in the figure. 



Hamilton group. Skanratele.^ lake. N. Y. 



Pterinopecten inteumedius. 



Page 63. 

 See Plate 83. • 

 Fig. 19. A left valve enlarged to two diameters. 



Hamilton group. Cayuga lake, N. Y, 



Pterinopecten fiijtextus. 



Page G7. 

 See Plate 82. 

 Fig. 22. A right \alve pi-esei-ving the test and showing the form of this valve. 



Hamilton group. From a bottlder. Pine Valley, Chemung Co.. A'. Y. 



Actinopteria subdecussata. 



Page no. 



See Plate 10. 

 Fig. 23. A small left valve. 

 Fig. 25. A somewhat larger example. 



Fig. 26. An individual of medium size showing the foi-m and surface markings. 



Pig. 27. A left valve, a large portion of which is broken away, showing the interior of the right valve. 

 Fig. 29. A large left valve. 



Fig. iiO. A i-ight valve .showing a greater extent of the wing than in the opposite valve. 

 Fig. HI. A s]iecimcn of medium .size, showing the interior of the left valve occupied by a portion of the 

 right, and rejn-e.senting the difference in the strength of the surface markings on the two 

 v;dves. 



Hamilton group. All from CauamUiigua hiki, r.vcrpl fir/. 2'? whir/i is from lielloiia. 

 Yates Co.. N. Y. 



ACTIX( MTI'.KI.V DECUSSATA. 



Pago 111. 



See Plate.'* 18, 20 and 84. 

 Fig. '24. A .'imall left valve. 



Hamilton group. Dresdtn, Yates Co., N. Y. 

 Fig. 28. .\ large left vuUr with the test removed, showing the usual form of the shell. 



Hamilton group, ('iiiirwddlf/nn lake. iV". Y. 



