BRACHIOPODA—ORTHIDJE. 



253 



by a convex deltidium. Surface covered with many fine elevated 

 striae crossed by finer concentric lines. 



Trenton of Kentucky, Tennessee, Illinois, Iowa, Wisconsin, 

 Minnesota. 



171. D. meedsi Winchell and Schuchert. (Fig. 303, e—h.) 



Ordovicic. 



Biconvex owing to the slight convexity of the pedicle valve. 



Hinge line shorter than the width of the shell below. Pedicle 



Fig. 303. a-d, Dinorthis deflecta ; e-h, D. meedsi; i-l, D. pectinella (Minn. 

 Geol. Surv.) ; m-o, D. sttbquadrata (Ind. Geol. Surv.). 



valve marked by a broad, shallow sinus. Surface marked by strong, 

 sharp, fasciculated striae crossed by growth lines. 

 Trenton of Iowa, Wisconsin, Minnesota. 



172. D. pectinella (Emmons). (Fig. 303, i-l.) Ordovicic. 



Pedicle valve flattened with a broad central depression. Brachial 



valve regularly convex. Surface marked with 22-30 prominent 



