PLATE I. 



AviCULOPJiCTEX ClEON. 



PajTC e. 

 Fig-. 1. 'I'l).- left valve of tlie specimen descviheii. The specimen is not so nearly entire as represented 

 in the H^jiirt*. 



Uppt-r llil.lerberggTOup. Columbus, Ohio. 



AviCDLOPECTEN IGNOTUS. 

 I'age 33. 

 Fig. a. A left vah e, fi-iiin. which the shell ha-s been almo-it entirely exfoliate.!. 

 Upper Helderberg- group. Near Victor, Ontarw Co.. iV. Y. 



AVICULOPECTEN (PtEUINOPECTEN?) TEKMI.NALIS. 

 Page 32. 

 Fig-. 3. A left valve enlai-ifccl to two iliametei-s. 



Upper Jlr-lilerberg group. lVUiiam.iviUe, Erie Co., N. Y. 



Ptekixopecten insons. 



I'age 59. 

 Pig. 4. The exfoliated left \aUe described, enlarged to two diametei-s. 

 Upper Helderberg groii]!. Western N. Y. 



Lyriopecten Daku.^nus. 



Page 41. 

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

 The si)ecimen is more e.\ten<leil on the anterior side than is i-epresented in the figure, and 

 there is an intermediate set of finer ray.s, also, not shown. 

 Upper Hehlerborg group. Le Itoij, N. Y. 



I'XERIXOl'ECTEN MULTII! ADIATU.S. 



l*afire 57 

 Fig. 0. The left valve de.sciii.ed. 



Fig. 7. A view of the impression left in th(' matrix. 



ri>|ier Helderberg group. Stafford, Geiiesee Co.. N. Y. 



AVICULOPECTEN INSIGNIS. 

 Pago U. 

 See Plates 3 and 81 . 

 Fig. S. An iinpeifect left valve. enlarg('d to two diamntei-s. 



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



AVICULOPECTEN PECTENIIOKMIS. 



Fig. y. Tlie original .s|>ei!ifuen descrilu'd. 



Ujiper Helilerberg gi-oup. Schoharie. N. Y. 



