MOLLUSCA. 509 



1868. Perna ovata Con., Cook's Geol. N. J., p. 726. 



1886. Modiola ovata Whitf., Pal. N. J., vol. i (Monog. U. S. 



G. S., vol. 9), p. 197, pi. 26, figs. 13-14. 



1905. Modiolus ovatus Johns., Proc. Acad. Nat. Sci. Phil. 

 P- 12. 



Description. "Shell ovate in outline, or elongate ovate, of 

 about a medium size, somewhat alate at the extremity of the 

 short hinge-line. Valves very ventricose, with nearly terminal 

 beaks, which are small, incurved, and not conspicuously raised 

 above the cardinal line. Umbonal ridge prominently rounded, 

 and the surface of the shell in front of it slightly sinuate, giving 

 a slight sinuosity to the basal line; posterior extremity of the 

 shell broadly rounded, and the anterior end narrow. Surface of 

 the shell marked by very fine, obscure lines of growth." (Whit- 

 field.) 



Formation and locality. Vincentown limesand, Timber Creek. 

 (Whitfield.) 



Geographic distribution. New Jersey. 



Modiola johnsoni Whitfield. 

 Plate LV., Figs. 14-15. 



1886. Modiola Johnsoni Whitf., Pal. N. J., vol. i (Monog. 

 U. S. G. S., vol. 9), p. 207, pi. 28, figs. 8-9. 



Description. "Shell small, measuring, in the only perfect ex- 

 ample of a cast seen, but little more than an inch in its extreme 

 length. Form ovate, widest behind the middle, and somewhat 

 narrowed anteriorly, while the posterior end is acutely rounded ; 

 beaks large, tumid, nearly anterior, slightly enrolled and approxi- 

 mate. Anterior end narrow, the projection scarcely extending 

 beyond the beaks. Valves very ventricose, the umbonal ridge 

 very full and rounded. Ligament short, slender, but distinctly 

 marked; a slight constriction or sulcus marks the basal half of 

 the width of the shell anterior to the middle of its length. Sur- 

 face of the shell as seen in casts marked by very fine concentric 



