588 CRETACEOUS PALEONTOLOGY. 



are fully as coarse as in C. kummeli, but there is only a single 

 row of smaller tubercles between the larger ones in that species, 

 instead of two as in C. kummeli. 



Formation and locality. Navesink marl, Mullica Hill (169) ; 

 Red Bank sand, near Middletown (112); Tinton beds, Beers 

 Hill cut, south of Keyport (I2Q 5 , I29 7 , 129), near Freehold 



Geographic distribution. New Jersey, Alabama, Mississippi. 



Cardium uniformis n. sp. 



Plate LXV., Figs. 1-3. 



Description. The dimensions of a perfect internal cast are: 

 height, 42 mm.; width, 35.5 mm.; thickness, 28 mm. Shell 

 irregularly subovate in lateral view and narrowly cordate in end 

 view. Beaks situated near the middle of the hinge-line and ele- 

 vated above it, pointed and incurved. Hinge-line arcuate; 

 anterior margin from the extremity of the hinge-line to the 

 middle of. the basal margin almost regularly arcuate; postero- 

 basal margin more sharply rounded into the posterior margin, 

 which is gently convex, being much straighter than the anterior 

 margin. Muscular impressions moderately large, not strongly 

 impressed. Inner free margins of the shell crenate, the corruga- 

 tions of the external surface of the shell recognizable upon the 

 internal casts to the urnbonal region, and in small individuals to 

 the beaks. The most prominent portion of the shell is in a line 

 extending obliquely from the beak to the postero-basal extremity, 

 this umbonal prominence is not at all angular, but the posterior 

 slope is more abrupt than the anterior, becoming slightly con- 

 cave as it approaches the cardinal extremity. The hinge-teeth, so 

 far as can be recognized from the internal cast, are in every way 

 similar to those of C. tenuistriatum. The surface markings, as 

 indicated by impressions of the outside, consist of rather broad, 

 flattened, radiating co<stse, with much narrower interspaces. 

 From the bottoms of the interspaces arise rows of spinules, very 

 strongly compressed laterally, which are nearly uniform in size 

 over the main central portion of the shell, there being only a 

 slight suggestion of each third row being slightly larger; upon 



