440 CRETACEOUS PALEONTOLOGY. 



left or oppositely; also by fine radiating striae which obscurely 

 diverge from a more or less median line and pass toward the 

 margin on either side. On the interior the margin of the valve 

 near the apex is more or less crenulate. The muscular scar is 

 small and lateral. Lower valve not yet observed." (Whitfield.) 



The dimensions of a rather small individual are: length, 32- 

 mm. ; width, 16.3 mm. 



Remarks. This species is not uncommon at some horizons in 

 the Cretaceous beds of New Jersey. In the Marshalltown clay- 

 marl near Swedesboro it occurs with the shell preserved, and in 

 the Wenonah sand near Craw fords Corner it is one of the most 

 abundant species but is always in the form of casts. From the 

 last of these localities some of the large individuals must have 

 attained a length of 50 mm. or more. The rather oblique, some- 

 what obscure plications shown upon the specimens illustrated by 

 Whitfield are doubtless due to the fact that those individuals, 

 during their life, were attached to the surface of some plicated 

 shell such as Exogyra costata. This plication of the shell is not 

 an essential specific character and has not been detected upon 

 any of the recently collected specimens. The fine radiating striae, 

 however, are highly characteristic of the species and can be 

 detected upon all examples retaining the shell and upon all im- 

 pressions of the external surface. Different individuals vary 

 more or less in general outline, but the elongate, narrow form, 

 somewhat acuminate towards the beak, seems to be the normal 

 form of the species. 



Formation and locality. Marshalltown clay-marl, near 

 Swedesboro (177); Wenonah sand, near Crawfords Corner 

 (i26 3 ) ; Red Bank sand, Shrewsbury River (119). 



Geographic distribution. New Jersey, Alabama, Tennessee. 



Ostrea subspatulata Forbes. 

 Plate XLII., Fig. 15. 



1845. Ostrea subspatulata Forbes, Quart. Jour. Geol. Soc. 



Lond., vol. i, p. 61, text figs. pp. 61 and 62. 

 1857. Ostrea subspatulata Con., Mex Bound. Surv., vol. i, pt. 



2, p. 155, pi. 10, figs. 33, 3b. 



