324 



NORTH AMERICAN INDEX FOSSILS. 



Wlf 



Fig. 411. Spivifer duodtnarim (Pal. N. Y., IV.). 



341. S. gregarius Clapp. (Fig. 412, d-e.) Devonic. 

 Small, ventricose. Cardinal extremities truncate or rounded. 



Pedicle valve regularly arcuate from beak to front with strongly 

 incurved beak and high cardinal area ; mesial sinus much produced 

 in front. Surface marked with 6-10 strong ribs on each side of the 

 median line. Entire surface covered with concentric striae which 

 toward the front become strong zigzag lines. 



Onondaga of New York, Ohio, Kentucky, Indiana, Ontario. 



342. S. grieri Hall. (Fig. 412, a-c.) Devonic. 

 Gibbous. Hinge line usually shorter than the width of the 



shell below, with rounded extremities. Pedicle valve with promi- 



FlG. 412. a-c, Spirifer grieri ; d-e, Spirifer gregarius ; f-h , Spirifer (Deltkyris) 

 raricosta. (After Nettleroth. ) 



