392 NORTH AMERICAN INDEX FOSSILS. 



XXIII. Paracardium Barrande. 

 Small, circular. Beaks high and slightly projecting. Surface 

 marked with fine, simple radial ribs. Hinge at times with a row 

 of minute tooth-like projections. Siluric and Devonic. 



Fjg. 500. Paracardium doris Hall, a small right valve, X5 (slightly transverse from 

 compression) ; a larger left valve, X3 ; interior, X IO - (N. Y. Mem., 6.) 



54. P. doris Hall. (Fig. 500.) Devonic. 



Beaks minute, incurved, and directed forward. Surface covered 

 with 20 to 25 fine, rounded ribs, separated by narrower furrows. 



Portage : New York, Pennsylvania. 



XXIV. Buchiola Barrande. 

 Cardinal line long and straight. Beaks pointing forward. A 

 row of minute, tooth-like projections often present on the outer 

 edge of the narrow cardinal area. Surface marked with a few 



,\ 



Fig. 501. Buchiola retrostriata, conjoined valves, X 3 > umbonal view of right 

 valve, showing the thin upturned edge of the hinge line, X 5 > a right valve with 

 sharply defined features, X 3- (After Clarke, Mem. 6, N. Y. State Mus.) 



broad plications crossed by fine lines curved prominently upward 

 as they cross the ribs. Siluric and Devonic. 



