556 CRETACEOUS PALEONTO'LOGY. 



gin above. Valves with an umbonal ridge extending in a nearly- 

 straight line from the beak obliquely backward to the postero- 

 basal extremity of the shell, becoming more angular posteriorly. 

 The postero-cardinal slope rather narrow, flat, slightly concave 

 or slightly convex. Surface of the shell marked with somewhat 

 regular, rather strong, concentric lines of growth which are less 

 conspicuous back, of the umbonal ridge. In internal casts the mus- 

 cular impressions are conspicuous and of about equal size. Free 

 margin of the shell crenate. 



Remarks. — In the recent collections of the Survey, this species 

 has been observed only in the Wenonah sand near Marlboro 

 where it occurs in the condition of modified casts of the interior 

 and impressions of the outside of the shell, by reason of the com- 

 pression of the imbedding material after the solution of the shell 

 substance. The type specimen, which is the only individual pre- 

 viously recorded, is a clean cut internal cast with the muscular 

 impressions strong, and without the markings of the external 

 surface of the shell impressed upon it. The Marlboro specimens, 

 however, agree so closely in their general form, size and propor- 

 tions with the type specimen, that there can be little or no doubt 

 as to their identity. Conrad's illustration of C. ripleyanu^ has- 

 much the form of this C. transversus, and it is possible that the 

 two forms may be identical. 



Formation and locality. — ^Wenonah sand, near Marlboro 



(130^)- 

 Geographic distribution. — New Jersey. 



Crassatellites cuneatus (Gabb). 

 Plate LXL, Pigs. 11-12. 



1860. Crassatella pteropsis Gabb, Jour. Acad. Nat. Sci. Phil., 



2d ser., vol. 4, p. 395, pi. 68, fig. 28. (Not C. pteropsis 

 Con., Jour. Acad. Nat. Sci. Phil., 2d ser., vol. 4, p. 279, 

 pi. 46, fig. 9.) 



1861. Crassatella cuneata Gabb, Synop. Moll. Cret. Form., pp. 



168, 169 (112, 113). 



'Proc. Acad. Nat. Sci. Phil. (1872), pi. i, fig. 7. 



