MOLLUSCA. 555 



any of the New Jersey specimens with that species. C. subplana 

 differs from C. vadosa in its much more depressed-convex valves, 

 those of C. vadosa being quite ventricose, especially towards the 

 umbo, although in their general outline and surface markings the 

 two species are much alike. 



Formation and locality. Marshalltown clay-marl, near 

 Swedesboro (177), Marshalltown (190); Wenonah sand, near 

 Marlboro (130) ; Navesink marl, Alantic Highlands (108), near 

 Walnford (i48 2 ), Crosswicks Creek (i47 4 , 149, 195), near 

 Jacobstown (150), Mullica Hill (169); Red Bank sand, near 

 Red Bank (116) ; Tinton beds, Beers Hill cut, south of Keyport 

 (i29 5 , I29 7 , I29 9 ), near Freehold (132). 



Geographic distribution. New Jersey. 



Crassatellites transversus (Gabb). 

 Plate LXL, Pig. 5. 



1 86 1. Crassatella transversa Gabb, Proc. Acad. Nat. Sci. Phil. 



(1861), p. 364- 

 1864. Crassatella transversa Meek, Check List Inv. Foss. N. A., 



Cret. and Jur., p. n. 



1868. Crassatella transversa Con., Cook's Geol. N. J., p. 726. 

 1876. Htea transversa Con., Proc. Acad. Nat. Sci. Phil. (1876), 



P. 275. 

 1886. Crassatella transversa Whitf., Pal. N. J., vol. i (Monog. 



U. S. G. S., vol. 9), p. 122, pi. 17, figs. 16-17. 

 1905. Crassatellites transversus Johns., Proc. Acad. Nat. Sci. 



Phil.. (1905), p. 14. 



Description. The dimensions of an internal cast are: length, 

 49 mm. ; height, 32 mm. ; thickness, 20 mm. Shell very inequi- 

 lateral, higher in front than behind, the beaks pointed in the in- 

 ternal casts and nearly erect, situated about one-third the length 

 of the shell from the anterior extremity. Anterior margin con- 

 vex in front, rounding to the hinge-line above and into the basal 

 margin below ; basal margin convex anteriorly and concave pos- 

 teriorly ; postero-basal margin sharply rounding into the obliquely 

 subtruncate posterior margin, which rounds into the dorsal mar- 



