5i6 CRETACEOUS PALEO'NTOLOGY. 



shell. The surface is also marked by more or less irregular 

 concentric lines of growth. 



Remarks: — This species is a much smaller and more elongate 

 form than P- occidentalis, and the two are never found associated, 

 in the same fauna. It also has a much smaller number of costse 

 which are relatively more distant than in the larger species. 



Formation and locality. — Wenonah sand, near Marlbora 



( 130) • 

 Geographic distribution.— -'New Jersey. 



Family ANATINIDAE. 



Genus Anatina Lamark. 



* 



Anatina jerseyensis n. sp. 



Plate LVIL, Figs. 1-4. 



Description. — The dimensions of a nearly complete internal 

 cast are : length, 44 mm. ; height, 29 mm. ; thickness, 1 1 mm. 

 Shell subovate in outline, a little gaping posteriorly, much broader 

 in front than behind; beaks transversely fissured, situated back 

 of the middle, pointing posteriorly. Antero-cardinal margin 

 straight and nearly horizontal in front of the beak, curving grad- 

 ually downward in front ; anterior margin broadly rounded from 

 the cardinal to the basal margins; basal margin nearly straight 

 in the middle, curving upward at each end; posterior margin 

 with its greatest extension above the middle of its height, curving" 

 into the basal margin below and the cardinal margin above; 

 post-cardinal margin strongly concave. Valves depressed con- 

 vex, most prominent in the umbonal region, abruptly compressed 

 towards the postero-cardinal extremity, the anterior and ventral 

 slopes gently convex. Shell marked by more or less irregular 

 concentric lines of growth. 



Remarks. — This species resembles Periplomya elliptica, but is 

 larger, less cuneate behind, and lacks the curved angular umbonal. 

 ridge of that species. It seems to be a true Anatina, although 

 it might be included in Conrad's genus Periplomya, it being diffi- 

 cult to distinguish between these two genera in the internal casts. 



