PLATE I. 



AVICULOPECTEN ClEON. 

 Page 6. 

 Fig. 1. The left valve of the specimen described. The specimen is not so nearly entire as represented 

 in the figure. 



Upper Helderherg group. Columbus, Ohio. 



AVICULOPECTEN IGNOTUS. 

 Page 33. 

 Fig. '-'. A left valve, from which the shell has been almost entirely exfoliated. 

 Upper Helderherg group. Near Victor, Ontario Co., J\ T . Y. 



AVICULOPECTEN (PtERINOPECTEN?) TERMINALIS. 

 Page 32. 

 Pig. 3. A left valve enlarged to two diameters. 



Upper Helderherg group. Williamsville, Erie Co., X. F. 



Ptehinopecten insons. 



Page 59. 

 Fig. 4. The exfoliated left valve described, enlarged to two diameters: 

 Upper Helderherg group. Western N. Y. 



Lyriopecten Dardanus. 



Page 41. 

 Fig. 5 A view of an imperfect left valve, taken from a gutta-percha impression of the natural mould. 

 The specimen is more extended on the anterior side than is represented in the figure, and 

 there is an intermediate set of finer rays, also, nut shown. 

 Upper Helderherg group. Le Roy, N. Y. 



Pterinopecten multiradiatus. 



Page 57. 

 Fig. G. The left valve described. 



Fig. 7. A view of the impression left in the matrix. 



Upper Helderherg group. Stafford, Ghsnesee Co., N. Y. 



AVICULOPECTEN INSIGNIS. 

 Page 34. 

 See Plates 3 and SI. 

 Fig. s. An imperfect left valve, enlarged to two diameters. 



Hamilton group. Stafford, Genesee Co., N. Y. 



AVICULOPECTEN PECTENIFORMIS. 

 Page 4. 

 Fig. '.i. The original specimen described. 



Upper Helderherg group. Schoharie, N, 1 



