422 CRETACEOUS PALEONTOLOGY. 



1868. Gervillia ensiformis Con., Cook's Geol. N. J., p. 726. 



1886. Geruilliopsis ensiformis Whitf., Pal. N. J., vol. r 



(Monog. U. S. G. S., vol. 9), p. 73, pi. 15, figs. 8-ii r 

 pi. 1 6, fig. 5. 



1887. Dalliconcha ensiformis White, Proc. Acad. Nat. Sci. 



Phil., 1887, p. 35, pi. 2, fig. 6. 



1905. Gervilliopsis ensiformis Johns., Proc. Acad. Nat. Sci, 

 Phil. (1905), p. 10. 



Description. "Shell of moderately large size and thickened, 

 falciform, very oblique; the body of the shell finally becoming 

 parallel to the hinge or even slightly recurved, narrowing pos- 

 teriorly and flattened on the surface. Hinge-line straight, short, 

 not more than one-fourth the length of the shell in grown indi- 

 viduals; posterior wing only moderately elevated, and the pos- 

 terior margin rapidly sloping backward from its extremity to 

 the body of the shell, anterior wing very slight, the anterior end 

 of the shell being squarely truncate at right angles to the hinge. 

 Beak of the shell small and terminal, elevated above the wing 

 and continuing in a ridge to the surface of the valve. Greatest 

 width of the shell opposite the posterior extremity of the hinge. 

 Surface of the shell lamellose, and marked by numerous concen- 

 tric varices of growth, and on the basal portion of the right valve 

 indications of fine radiating lines occur. Hinge area moderately 

 wide, marked by several transverse ligamental pits, arranged at 

 a little more than one-fourth of an inch apart, and also by nu- 

 merous oblique corrugations. Muscular imprints large and 

 obliquely situated. Substance of the shell highly nacreous 

 throughout and iridescent." (Whitfield). 



The dimensions of a large, nearly perfect individual illustrated 

 by Whitfield, are: extreme length, 190 mm.; length of hinge- 

 line 48 mm.; height at posterior extremity of hinge-line, 44 

 mm. ; greatest width of body of shell, 35 mm. 



Remarks. Whitfield states that the only specimens of this 

 species from New Jersey which have come under his observation 

 are from Woodbury. These Woodbury specimens preserve the 

 shell in most cases, in an excellent state of preservation, but none 



