BRACHIOPODA—PROTREMATA. 



273 



222. A. verneuili (Hall). (Fig. 330.) Devonic. 



Globose with width generally exceeding length. Pedicle valve 

 with distinct sinus. Brachial valve very elevated with exceedingly 

 gibbous beak, strongly incurved and covering the foramen of the 

 opposite valve. 



Helderbergian of New York, Tennessee, Greenland. 



LXV. Conchidium Linnaeus. 

 Elongate subpentagonal, strongly inequivalved, biconvex, with- 

 out well defined median sinus and fold. Pedicle valve highly 

 arched ; delthyrium very broad. Spondylium narrow and deep, 



Fig. 331. Conchidium occidentale (Canadian Geol. Surv. ). 



supported by a high septum. Beak of brachial valve closely in- 

 curved ; cardinal process small; a pair of median septa in pos- 

 terior portion of valve. Surface with numerous radiating plica- 

 tions. Siluric-Devonic. 



223. C. occidentale Hall. (Fig. 331.) Siluric. 

 Ovoid. Plications scarcely equal in width to the spaces between 



them. 



Guelph of Wisconsin, Ontario. 



224. C. nettelrothi Hall & Clarke. (C. knighti Nettelroth.) 

 (Fig. 332.) Siluric. 

 Differs from the preceding in its proportionately greater con- 

 vexity of valves, narrower form, higher pedicle valve, with strongly 

 incurved umbo and pronounced flattening* on either side of the 

 delthyrium, and in the coarser close and sparse plications which 

 extend to the beaks. 



