328 



NORTH AMERICAN INDEX FOSSILS. 



cardinal area extremely elevated, nearly flat above, with a large, 

 open delthyrium. Brachial valve moderately convex. Sinus and 

 fold bounded on each side by 16 to 20 plications. Length about 

 Y^ inch, 



Hamilton of Ohio, Kentucky, Indiana, Illinois, Wisconsin. 



349. S. oweni Hall. Devonic. 



Very similar to 5. granulosus but differs in its smaller size, its 

 subangular plications and median sinus, fewer plications (15 to 17 

 on each side the median fold and sinus), its subauriculate hinge 

 extremities and especially in lacking the granulose surface so 

 characteristic of the latter species. 



Hamilton of Falls of Ohio region and Michigan. 



/ 







Fig. 417. Spirifer granulosus (Pal. N. V., IV.). 



350. S. granulosus (Conrad). (Fig. 417.) Devonic. 



Large, robust and gibbous with high, curved cardinal area. 

 Brachial valve with a prominent rounded fold, marked by a median 

 depression. Plications low. Surface strongly granulose. 



Hamilton. Widely distributed throughout eastern United States. 



