442 CRETACEOUS PAEEONTOLOGY. 



1864. Ostrea crenulimarginata Meek, Check List Inv. Foss. N. 



A., Cret. and Jur., p. 6. 

 1869. Ostrea crenulimarginata Coquand, Monog. Gen. Ostrea 



Terr. Cret., p. 51, pi. 17, figs. 12-13. 

 1884. Ostrea crenulimarginata White, 4th Ann. Rep. U. S. G. S., 



p. 294, pi. 40, fig. 2. 

 1886. Ostrea crenulimarginata Whitf., Pal. N. J., vol. i 



(Monog. U. S. G. S., vol. 9), p. 30, pi. 3, figs. lo-ii. 



Description. — "Shell, as seen in a single upper valve, depressed 

 convex and moderately smooth, of an irregular ovate outline, 

 and marked by but few concentric lines of growth more promi- 

 nent than striae. Faint indications of radiating striae show ob- 

 scurely, but are more in the substance of the shell than on the 

 surface. On the interior the margin is finely crenulate for two- 

 thirds the length of the valve, being strongest near the hinge and 

 becoming fainter in the forward part. Muscular scar large, reni- 

 form, and situated above the middle of the shell." (Whitfield.) 



The dimensions of a large example are : height, 47 mm. ; 

 length, 44 mm. 



Remarks. — No specimens referable to this species have been 

 observed in the recent collections. Whitfield has illustrated one 

 specimen which he has so identified, but it is quite unlike Gabb's 

 original figure of the species in being much broader along the 

 hinge-line. It seems to have the crenulations along the margin 

 similar to those upon Gabb's specimen, and the identification may 

 be correct. 



Formation and locality. — Navesink marl, Marlboro (Whit- 

 field). 



Geographic distribution. — New Jersey, Tennessee. 



Ostrea monmouthensis n. sp. 



Plate XLIIL, Fig. 15. 



Description. — Shell slightly oblique, subovate in outline, the 

 dimensions of the type specimen being : length, 28 mm. ; width, 

 22 mm. Upper valve depressed convex, nearly smooth, marked 

 only by inconspicuous concentric lines of growth. Along. the 



