PLEIOCENE FOSSILS. « 



ARCA IMPROCERA.— Con. 



Plate XV., Figs. 4 and 5. 



Area improcera, Con., Foss. Ter. For., p. 60, pi. 31, fig. 5. 



A. testa oblonga racliatim costata, latere buccali brevi, rotundato, superne angulato ; latere 

 anali, angulato, oblique truncato ; costis valvce dextralis crenulatis ; valvce sinistralis, costis 

 ad laterem buccalem crenulatis ad laterem analem Icevibus ; area ligamenti angusta, sulcata ; 

 umbonibus approximatis. 



Description. Shell oblong, radiately costate ; buccal margin short, rounded, angular 

 above ; anal side angulated, obliquely truncate ; ribs on the right valve crenulate ; on the 

 left valve crenulate on the buccal side, smooth on the anal side ; ligament area short, nar- 

 row, furrowed ; umbones approximating. 



This pretty species is distinguished by the short hinge line which forms angles with the 

 sides ; the anal side is somewhat produced and angulated, with the ribs flattened and smooth. 



Plate XV., Fig. i. Exterior of left valve, and kmge and teeth of right valve. 

 " 5. End view, showing outline, hinge and umbones. 



Locality. Darlington District. 



Museum, College of Charleston. 



