BRACHIOPODA — ORTHIDJE. 



261 



190. D. subaequata (Conrad). (Fig. 311,/-/*.) Ordovicic. 



Both valves convex, the pedicle valve more than the brachial 

 especially at the umbo. Surface marked with fine radiating striae 

 which are perforate at intervals. 



Trenton of Missouri, Wisconsin, Minne- 

 sota, Iowa, Quebec. 



191. D. elegantula (Dalman). (Fig. 312.) 



Siluric. 



Pedicle valve very strongly convex with a 

 high, narrow cardinal area. Brachial valve 

 nearly flat and marked with an undefined 

 median sinus. Strise fine and close set. 



Clinton and Niagara ; widely distributed 

 throughout eastern North America. 



Fig. 312. 



elegantula. 



Dalmanella 

 (After Hall.) 



192. D. perelegans Hall. (Fig. 313.) Devonic. 



Pedicle valve convex but not subcarinate as in D. subcavinata. 



V 



^A 



Dalmanella perelegans . ( A fter Hall.) 



Brachial valve very convex and only slightly depressed medially. 

 In other respects very like D. subcavinata. 

 Helderbergian of New York and Tennessee. 



193. D. subcarinata Hall. (Fig. 314.) Devonic. 



Pedicle valve very convex, subcarinate along median line; umbo 



strongly incurved over the cardinal area. Brachial valve slightly 



