26 NORTH AMERICAN INDEX FOSSILS. 



345. S. acuminatus (Conrad). (Fig. 414.) Devonic. 



Large, ventricose. Pedicle valve with umbo incurved over the 



wide delthyrium. Surface distinguished by the very elevated and 



angular mesial fold and deep sinus, bounded by 16 to 20 plications. 



■"r>*. 



J0- 



\ 



'%'-- 

 •-...• 



f -' r ' "V 



Fig. 414. Spirifer acuminatus external views and internal mold (Pal. N. Y., IV.). 



Onondaga and Hamilton of New York, Ohio, Kentucky, Indiana. 



346. S. divaricatus Hall. (Fig. 415.) Devonic. 

 Ventricose. Hinge line less than width of shell below, with 



rounded extremities. Cardinal areas wide. Beaks of both valves 

 prominent and arching. Sinus and fold prominent and angular. 

 Whole surface, including sinus and fold, covered with fine, rounded, 

 bifurcating plications which are crossed by fine, zigzag, concentric 

 striae. 



Onondaga and Hamilton of New York, Ohio, Kentucky and 

 Port Colborne, Canada. 



347. S. euryteines Owen. (Fig. 413, d-e.) Devonic. 

 Semielliptical. Cardinal area wide and slightly concave ; beaks 



sometimes more than y 2 inch apart. Fold and sinus bounded on 



