PELECYPODA—TELEODESMACEA. 535 



480. C. gregaria Hall. Devonic. 

 Smaller than C. bellistriata, with more curving posterior end 



and finer striae. 



Hamilton-Chemung: New York, Pennsylvania. 



481. C. bellistriata Conrad. (Fig. 727, c y d.) 



Devonic-Mississippic. 

 Distinguished by its strong surface striae. 



Marcellus-Chemung : northern Appalachian region ; abundant 



in Hamilton of New York, Pennsylvania, Maryland, Lower Wav- 



erly of Ohio. 



482. C. oblonga Hall. (Fig. 728.) Mississippi. 



a 



'£> ,d e 



Fig. 728. Cypricardella oblonga: a, cardinal view ; b, internal mold of right valve, 

 showing muscular impressions ; c, hinge of right valve enlarged ; d, e, left and right 

 valves. (After Whitfield.) 



Base subparallel to hinge line. Posterior margin obliquely 

 truncate. 



Indiana (St. Louis), Kentucky (St. Genevieve). 



CXXXIII. Cypricardinia Hall. 

 Inequivalve, with more convex right valve, somewhat rhomboid 

 or trapezoidal. Anterior end short and rounded ; posterior wider 

 and obliquely truncate. Beaks nearly at anterior extremitiy. 

 Umbonal slope prominent. Surface marked by concentric lamel- 

 lose ridges with intermediate fine growth striae and in some species 

 radial striae. Two to three cardinal teeth present. Ligament ex- 

 ternal. Pallial line simple. Shell thicker than in Modiolopsis 

 and concentric striae stronger. Siluric-Mississippi. 



483. C. arata Hall. Siluric. 

 Surface crossed by strong concentric lamellose ridges. 

 Niagaran : Indiana, Wisconsin, Oklahoma. Also Siluric of 



Alaska. 



484. C. lamellosa Hall. Devonic. 

 Gibbous, with short anterior and long posterior extremities. 



