322 



NORTH AMERICAN INDEX FOSSILS. 



cyclopterus in the more elevated beak of the pedicle valve, the 

 more numerous plications and in the angular character of sinus 

 and fold with occasionally obscure plications. 



Helderbergian (Becraft and Port Ewen) 

 of New York. 



'\V. 



CM 338. S. murchisoni Castelnau. (Fig. 

 409.) Devonic. 



Pedicle valve with elevated and incurved 

 beak and high, concave cardinal area. 

 Surface marked by 5 to 8 plications on 

 each side of the prominent sinus and fold. 

 Entire shell surface covered with fine, 

 v 0v' close concentric and radiating striae. In- 



W • ternal mold of pedicle valve distinguished 



by a large, prominent striated process, in- 

 dicating the form and dimensions of the 

 muscular area. The mold is strongly 

 papillose on each side of this area. 



Oriskany of New York, Maryland, Ontario. 

 339. S. arenosus (Conrad). (Fig. 410.) Devonic. 



Large, with valves of about equal convexity. Pedicle valve 

 with broad and slightly incurved umbo. Mesial sinus very shallow 



FlG. 408. Spirifer concin 

 nus (Pal. N. Y., VIII.). 



€ 





i 





% '{.'"?:■■■ -v' 



FlG. 409. Spirifer murchisoni. External views and internal mold (Pal. N. Y., III. ) 



