BRACHIOPODA—PROTREMA TA. 



277 



LXIX. Pentamerella Hall. 

 Pentameroid, more or less rotund, with a sinus on pedicle valve 

 and fold on brachial. Much like Clorinda but larger and strongly- 

 plicate, with a narrow cardinal area. Brachial valve with the crural 

 plates supporting septa conjoined so as to form a broadly sessile 

 spondylium. ? Siluric-Devonic. 



231. P. arata (Conrad). (Fig. 2>Z7-) Devonic. 



Ovate, with gibbous pedicle valve which in old age becomes very 



arcuate with strongly incurved beak. Brachial valve only moder- 



FiG. 337. Pentamerella arata, average sized, and extremely old age individuals 

 (Pal. N. Y.), 



ately convex. Surface covered with angular plications, often 

 developed only below the first third of the length and usually 

 bifurcating. 



Schoharie and Onondaga of New York, Ohio, Kentucky, 

 Indiana, Michigan, Ontario. 



232. P. pavilionensis Hall. Devonic. 



Differs from the preceding, in having the valves more nearly 

 equally convex, and fewer rounded plications which become 

 obsolete toward the beak and often on lateral slopes; and in having 

 a well defined fold and sinus with four and three (or two) plications 

 respectively. 



Hamilton beds of New York, Falls of the Ohio, Michigan, etc. 



