26o NORTH AMERICAN INDEX FOSSILS. 



Order OPISTHOPARIA Beecher. 

 VI. CoNOcoRYPHE Corda. 



Cephalon semicircular; genal angles produced into spines. 

 Glabella lobed, not extending to frontal border, narrow in front 

 and wide behind, and with three or four backwardly directed fur- 

 rows and a well marked neck furrow. Fixed cheeks very large; 

 free cheeks narrow. Thorax of 14 segments ; pleura grooved. 

 Pygidium small, with entire margin; axis with two to eight seg- 

 ments. Cambric. 



4 



13. C. baileyi Hartt. (Figs. 1551 ; 1552,0.) 



Cambric. 



Fig, 155^' Conocoryphe baileyi^ cephalon, X %• 



Anterior portion of cephalon finely striated vertically to the 

 border. 



St. John group (Acadian) of New Brunswick. 



14. C. elegans Hartt. (Fig. 1552, &.) Cambric. 



Fig. 1552. <2, Conocoryphe baileyi, pygidium ; b^ C. elegans, cephalon ; c, Ctenocephalus 

 matthewi ; d, Olenelhis iddingsi,yow[ig. (After Walcott.) 



Anterior fold bending inward toward glabella, forming a broad 

 V-shaped elevation. 



St. John group (Acadian) of New Brunswick. 



VII. Ctenocephalus Corda. 



Like ConocoryphCj but with a lobe in front of the glabella ; gla- 

 bella less strongly defined, free cheeks larger, pygidium much 

 smaller, and thoracic segments 15. Cambric. 



