BRA CHI OP OD A — TEL O TREMA TA . 



339 



376. R. laevis (Hall). (Fig. 432.) Upper Devonic. 

 Ventricose with rounded cardinal extremities. Length to 



breadth as 2 to 3 or as 3 to 4. Pedicle valve with abruptly atten- 

 uate and arching beak ; foramen partially closed by an arching 

 and very convex pseudo-deltidium. Sinus either shallow or deep. 

 Brachial valve only moderately convex with an undefined mesial 

 fold. Surface usually smooth or marked only by concentric growth 

 lines. In old age at times there appear a few obscure radiating folds. 

 Portage of New York. 



377. R. cooperensis (Swallow). Mississippi. 

 Small (length and breadth about § inch), gibbous, with greatest 



breadth a little above the middle. Front subtruncate or slightly sin- 

 uous in the middle. Pedicle valve much the more gibbous with a 



Fig. 433. Retiailaria pseudolineata, X -f> with enlargement of part of surface. 



(After Hall.) 



shallow mesial sinus; beak prominent and incurved beyond the 

 hinge line ; foramen wide and triangular. Brachial valve depressed- 

 convex with low mesial fold. Surface covered with 2 to 4 very 

 obscure and depressed radial plications on each side the fold 

 and sinus. 



Kinderhook of Tennessee, Indiana, Missouri, Iowa. 



378. R. pseudolineata (Hall). (Fig. 433.) Mississippi 

 Width greatly exceeding length. Peoicle valve with shallow 



mesial sinus and prominent incurved beak. Surface marked by 

 more or less regular concentric lamellose folds or wrinkles and ra- 

 diating striae extended into long spines from the edges of the folds. 

 Burlington-Keokuk of Missouri, Indiana, Illinois?, Iowa. 



379. R. setigera (Hall). (Fig. 431, c-d.) Mississippi. 

 Much like R. pseudolineata, but differs in that here the length 



and breadth are more nearly equal and the beak is higher and 

 narrower. 



Kaskaskia of Kentucky, Illinois, Utah. 



