206 PALEONTOLOGY OF NEW JERSEY. 



usually free, the casts being found scattered free through the marl, and 

 where the shells are found they present but little evidence of having grown 

 attached, except, perhaps, in their very early stages. Many of them are 

 so convex on the lower valve as to be almost gryphsea-like in form. 

 Still the internal and hinge features are those of a true oyster. 



Formation and locality. — [n the lower layers of the Upper Marls at 

 Farmingdale, Squankum, Shark River, and near New Egypt, as cast of 

 the interior; and near Vincentown, New Jersey, preserving the shell. Speci- 

 mens of the shell preserved, but highly pyritous, sometimes occur also at 

 Shark River, New Jersey, but rarely, and are soon destroyed in collections 

 by the decomposition of the pyrite. 



Genus GRYPHEA Sow. 



Gryphcea Bryani. 



Plate XXVII, Figs. 6-9. 



Ostrea Bryani Gabb. Proc. A. N. Sci., Phil., 1876, p. 321. 

 Comii. Gryphcea vesicularis Lam. 



The examples upon which this species was established do not appear 

 to me to differ very materially from many of the small forms referred to 

 Gryphcea vesicularis, as it occurs in the Terebratula beds of the middle 

 marls; and it certainly does not appear reasonable to place them under the 

 genus Ostrea, if we recognize Gryphaa as a good generic group, as they 

 appear to possess all the essential features of that genus. The shells which 

 I find marked as the types of Mr. Gabb's species are elongated and very 

 generally somewhat regularly increasing in width from the upper part for- 

 ward, with sometimes a tendency to lateral extension to the left as one looks 

 on the smaller valve. The lower valve is strongly convex and rather 

 strongly arcuate, while the upper is slightly concave on the exterior. The 

 lai-ger valve has usually a well marked cicatrix of attachment and a mod- 

 erately developed cartilage area, and the smaller, the latter feature corre- 

 spondingly large, but nearly vertical to the plane valve. In the feature of 

 lateral extension these shells somewhat resemble the G. PitcJieri of the South 

 and Southwest, and on some of the specimens obscure indications of radia- 

 ting plications occur on the lower valve. 



