BRA C HI POD A — TEL TREMA TA . 



353 



Devonic. 

 Surface marked by 



less prominent beak ; from A. spiriferoides in its smaller size, the 

 regularity of its lines of growth and the more prominent umbo. 



Onondaga and Hamilton of Kentucky, Indiana, Michigan, Mis- 

 souri, Iowa, Manitoba. 



412. A. spiriferoides (Eaton). (Fig. 461.) 

 Robust. Front indented by a deep sinus. 



coarse irregular concentric lam- 

 ellae. 



Onondaga and Hamilton of 

 New York, Pennsylvania, Mary- 

 land, Virginia, Ontario. 



413. A. angelica Hall. (Fig. 



462.) Devonic. 



Gibbous, deeply sinuate, with short hinge line and very prom- 

 inent beak. Surface marked by regular, equidistant lamellae. 



Chemung of New York, Pennsylvania, Nevada. 



414. A. lamellosa (L'Eveille). (Fig. 463.) Lower Carbonic. 

 Length about two thirds of width. Hinge line long, nearly 



straight, and rounded at extremities. Anterior margin usually 

 produced and subangular in the middle at the termination of the 

 mesial fold and sinus. Brachial valve slightly the more convex and 



Athyris angelica (Pal. N. 



FlG. 463. Athyris lamellosa (Pal. Ohio). 



rising into a low, rounded mesial fold. Pedicle valve with shallow 

 mesial sinus. Surface of both valves with 8 or 10 strongly pro- 

 jecting lamellae. Differs from other species in its transversely 

 elliptical form. 



Waverly-Keokuk of Ohio, Kentucky, Indiana, New Mexico. 



CXXII. Cliothyris King. 

 Differs from Athyris in the surface ornamentation which here 

 consists of concentric rows of flat spinules and also in the spirals 

 and loop. Mississippic-Permic. 



