338 NORTH AMERICAN INDEX FOSSILS. 



B. Apparently spineless **. 



** Surface usually smooth. Shell large 376. R. Iccvis. 



** Surface smooth ; shell of medium size 375. R. nevadaensis. 



** Surface' marked by crenulate concentric lines. Small 380. R. perplexa. 



374. R. fimbriata (Conrad). (Fig. 431, a-b.) Devonic. 



Gibbous, with rounded cardinal extremities. Pedicle valve with 



a P 



Fig. 431, a-b. Reticularia fimbriata ; c-d, Reticulata setigera. (After Hall.) 



small beak incurved over the high and concave cardinal area which 

 is striated vertically. Brachial valve with small and slightly arch- 

 ing beak. Surface marked by 3 to 

 9 low plications on each side the 

 mesial fold and sinus, crossed by 

 imbricating lamellose striae ; these 

 striae are studded with elongate 

 nodes or tubules. 



Oriskany- Ithaca. Widely dis- 

 tributed through North America. 



375. R. nevadaensis (Walcott). 



(Fig. 435,£.) Upper Devonic. 



Less transverse than preceding; 

 fold and sinus often more angular ; 

 no plications, surface appearing 

 smooth. 

 Devonic limestones of Nevada. 



Fig. 432. Reticularia /«w, X | 

 (Pal. N. Y. IV.). 



