I'I.ATK I..\X.\III— (Juiitimic-il. 



Pteuinopecten exfoi.iatus. 



tage 01. 



See Plate 1. 



Fig'. G. A left viilve as obtained from an impression of the matrix, showing- the foi-ui and surface charactei-s. 



Fi{r. 7. A laige imperfect left valve with the test almost wholly exfoliated ami ]>resenling a strongf contrast 



with the preceding. 



Limestone of Miircellus .«hale. Qeiiesee Co., N. Y. 



Cren'ipecten Leon. 



Page tM. 

 See Plate y. 

 Fig-. 8. The left valve described sliowinj^ the hinge characters and I'oi-m of the valve. 

 Cliemung- g-roup. Lemi, Ckiftaraugns Co., N. Y. 



Crenipectex likatus. 



IMge >*7. 

 .See Plate i». 

 Fig-. '.I. A left valve showing the form and size of the ears given in correction of tig. 24, plate H. 

 Chemung gi'ouj). Cnmtewavgo, Cnttavangus Cn., N. Y. 



Ckenipecten kmpomtus. 



Page S3. 



See Plate H. 

 Fig. 10. A snnill left valve. 



C'hianung gronj). (Ihnii, J\'. Y. 



I'iKlMNEA FLAHELLA. 

 Page 93. 

 Se.- Plates 14 and 1. "5. 

 Fig. 11. .\ large left valve showing but three .strong radii. 



Chemung gronp. Lawremmnlle, Tioyii Co., Pa. 

 Fig. I'J. The internal mould of a left valve, showing tin- liL.'-nini'ntal area, lateral and cardinal tei'th. pallial 

 line and both muscular impi-e.ssions. 



Hamilton grouj). Si-hoharie Co., A. 1. 



PtEKINEA PINGUIS. 



Page 92. 

 See Plate Ih. 



Fig. 13. A left valve showing the form ami proi)ortions ; redrawn from the specimen of tig. '1, plate 15. 

 Upper Helderberg grovij). Near Colnmbii.'s, Ohio. 



PtEKINEA GKANDl.'*. 

 Page 91. 

 Fig. 14. A large left valve imperfect on the anterior end. 



Upi>er Helderberg group. Lexington, Siott Co., Iml. 



