408 CRETACEOUS PALEONTOLOGY. 



of the beaks, and the more conspicuous sinus, especially in the 

 right valve, extending 1 from the beaks obliquely to the ventral 

 margin. The casts of this species are also nearly destitute of 

 any indications of the radiating costae of the shell, while in Area 

 rostellata the impressions of the plications are clearly seen. 



Formation and locality. Merchantville clay-marl?, Burling- 

 ton County (Coll. Phil. Acad. Sci.) ; Navesink marl, Atlantic 

 Highlands (108), Crosswicks Creek (149, 195). 



Geographic distribution. New Jersey. 



Area rostellata Morton. 

 Plate XXXIV., Figs. 4-5. 



1834. Area rostellata. Mort, Synop. Org. Rem. Cret. Gr. U. S. r 



p. 64, pi. 3, fig. n. 

 1861. Cibota rostellata Gabb, Synop. Moll. Cret. Form., p. 165 



(109). 

 1864. Cibota rostellata Meek, Check List Inv. Foss. N. A., Cret, 



and Jur., p. 9. 



1868. Area rostellata Con., Cook's Geol. N. J., p. 725. 

 1886. Cibota rostellata Whitf., Pal. N. J., vol. i (Monog. U. S. 



G. S., vol. 9), p. 91, pi. 11, figs. 34-36. 

 1905. Area rostellata Johns., Proc. Acad. Nat. Sci. PhiL 



(1905), P- 9- 



Descripion. "Shell trapezoidal and very oblique, the length 

 being about twice and a half the height, with subparallel cardinal 

 and basal margins, posterior end very obliquely prolonged below, 

 and the anterior end rather rapidly rounding backward from 

 near the hinge-line to its junction with the base. Basal margin 

 very perceptibly sinuate nearly opposite the beaks and apparently 

 very slightly gaping. Valves moderately inflated, most ventri- 

 cose on the umbones just anterior to the sulcus, which crosses 

 them from the beak to the sinus of the base, and then rapidly 

 declining to the anterior extremity, but sloping quite gradually 

 on the posterior side. Beaks moderately large, somewhat pro- 

 jecting above the hinge and slightly incurved; situated at about 



