MOLLUSCA. 437 



1886. Ostrea denticulifera Whitf., Pal. N. ]., vol. i (Monog. 



U. S. G. S., vol. 9), p. 29, pi. 3, figs. 8-9. 

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



(1905), p. 10. 



Description. "The shells of this species are very small, flat- 

 tened, thick, and extremely irregular in form. Those originally 

 described by the author seem to have been moderately convex, 

 but the New Jersey specimens are extremely shallow and gen- 

 erally elongated, with the surface obsoletely striate; even on the 

 smoothest specimens the striae show beneath the surface. The 

 ligamental area is small and the margin crenulate on some indi- 

 viduals to near the front of the shell, the crenulations being 

 strong and tooth-like, and leaving ridges on the sides of the 

 valves as the shells thicken with age. Muscular impression large, 

 lateral, and usually below the middle of the length." (Whit- 

 field.) 



Remarks. This species has not been recognized in the recent 

 collections of the Survey. The specimen illustrated by Whitfield 

 is a Haddonfield example originally identified as belonging to 

 the species by Conrad, the author of the species, but it is much 

 more elongate and narrower than the original illustration of the 

 species from Mississippi and it is quite possible that the identifi- 

 cation is incorrect. In general form this Haddonfield example 

 agrees more nearly with the specimens of Ostrea plumosa, but 

 it is a thicker shell, and is not so distinctively marked by the fine 

 radiating lines. 



Formation and locality. Woodbury clay, Haddonfield (183). 



Geographic distribution. New Jersey, Mississippi, Tennessee. 



Ostrea panda Morton. 

 Plate XLII., Fig. 10. 



1833. Ostrea panda Mort., Am. Jour. Sci., ist ser., vol. 23, p. 



293- 



1834. Ostrea panda Mort., Synop. Org. Rem. Cret. Gr. U. S., 



p. 51, pi. 3, fig. 6, pi. 19, fig. 10. 



1861. Ostrea panda Gabb, Proc. Acad. Nat. Sci. Phil., 1861, 

 P- 328. 



