516 CRETACEOUS PALEONTOLOGY. 



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 costae 

 which are relatively more distant than in the larger species. 



Formation and locality. Wenonah sand, near Marlboro- 



(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, n 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 Ijhe 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. 



