BRACHIOPODA — TELOTREMATA. 



323 



and often producing merely a flattening of the surface. Mesial 

 fold moderately elevated. Whole surface covered with 20 to 40 



Fig. 410. Spirifer arenosus. External views and mold of interior (Pal. N. Y. , III. ). 



low and even plications. Occurs largely as internal molds in the 

 sandstones. 



Oriskany and Onondaga (?) of New York, Pennsylvania, Mary- 

 land, Virginia, Ontario. 



340. S. duodenarius (Hall). (Fig. 411.) Devonic. 



Somewhat resembles S. cyclopterns but differs in its more ex- 

 tended hinge line which here forms the greatest width of the shell, 

 in the narrow cardinal area which is here almost linear and in the 

 less conspicuous strise. Both valves are flattened at the cardinal 

 extremities. 



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



