MOLLUSCA. 435 



1869. Ostrea cretacea Coquand, Monog. Gen. Ost. Terr. Cret.^ 



p. 52, pi. 23, figs. 4-5. 

 '1884. Ostrea cretacea White, 4th Ann. Rep. U. S. G. S., p. 294. 

 1905. Ostrea cretacea Johns., Proc. Acad. Nat. Sci. Phil., 1905, 



p. 10. 



Description. — Shell nonplicate, irregularly subovate in outline, 

 higher than wide, narrowest across the hinge-line; the dimen- 

 sions of a rather short, nearly complete internal cast of a lower 

 valve are: height, 22.5 mm.; width, 18.5 mm. Lower valve 

 moderately convex, upper valve nearly flat, surfact of the casts 

 marked only by more or less irregular concentric undulations. 



Remarks. — The shells which have been identified as Ostrea 

 cretacea in the recent New Jersey collections, occur only in the 

 form of internal casts in the Cliffwood clay. In so far as the 

 characters of the specimens are preserved, they seem to agree in 

 all essential characters with authentic representatives of this 

 species from the south. Morton originally described the species 

 as coming from the Cretaceous, but more recent authors have 

 sometimes referred it to the Tertiary, but the Cretaceous age of 

 the species is sufficiently demonstrated by the collections in the 

 National Museum at Washington made by Dr. T. W. Stanton, 

 who has found it .to be especially characteristic of the lower beds 

 of Ripley age in the Chattahoochie River section. 



formation and locality. — Cliffwood clay, Cliffwood Point 

 (los). 



Geographical distribution. — New Jersey, Georgia, Alabama, 

 Arkansas. 



Ostrea congesta Conrad? 

 Plate XLIIL, Fig. 16. 



1843. Ostrea congesta Con., Nicollet's Rep. Expl. N. W., p. 167. 

 1856. Ostrea congesta Hall, Pac. R. R. Rep., vol. 3, p. 100, 



pi. I, fig. II. 

 1869. Ostrea congesta Coquand, Monog. Gen. Ostrea Terr. 



Cret., p. 49, pi. 17, fig. 5. 

 1876. Ostrea congest Meek, Inv. Cret. and Ter. Foss. Up. Mo., 



p. 13, pi. 9, figs. I, a-f. 



