MOLLUSCA. . 455 



shell to G. aucella Roem., first described from Texas, but the New 

 Jersey shell is entirely diiiferent from the Texas specimens. 



Formation and locality. — Hornerstown marl, near Woodstown 

 (i8i), near New Egypt (1422, 142^), near Mullica Hill (182). 



Geographic distribution. — ^New Jersey. 



Genus Gryphai;osTrEa Conrad. 

 Gryphaeostrea vomer (Morton). 



Plate XUV., Figs. 6-1 1. 



1834. GryphcBa vomer Mort., Synop. Org. Rem. Cret. Or. U. 



S., p. 54, pi. 9, fig. 5. 

 1861. Bxogyra lateralis Gabb, Synop. Moll. Cret. Form., p. 179 



(123). 

 1864. Bxogyra lateralis Meek, Check List Inv. Foss. N. A., 



Cret. and Jur., p. 6. 

 1868. Gryphostrea lateralis Con., Cook's Geol. N. J., p. 724. 

 1876. GryphcBostrea vomer Meek, Rep. Inv. Cret. and Tert. 



Foss. Up. Mo., p. II. 

 1886. Gryphceostrea vomer Whitf., Pal. N. J., vol. i (Monog. 



U. S. G. Sl, vol. 9), p. 195, pi. 26, figs. 11-12. 

 1901. Ostrea {Gryphaeostrea) vomer Clark, Eocene Rep., Geol. 



Surv. Md., p. 193, pi. 50, figs. 1-5. 

 1905. Ostrea {Gryphceostrea) vomer Johns., Proc. Acad. Nat. 



Sci. Phil., (1905), p. II. 



Description. — The dimensions of a rather large individual are : 

 length, 55 mm.; greatest width, near the hinge-line, 33 mm. 

 Shell narrowly elongate, subovate or subelliptical in outline, more 

 or less strongly arcuate from beak to base, and often more or 

 less twisted laterally. Lower or right valve more or less strongly 

 convex, the beak small, pointing forward, a little coiled; in 

 typically developed shells both the anterior and posterior cardinal 

 regions are produced into compressed auricular extensions, one 

 or both of which are frequently wanting; the surface of the valve 

 nearly smooth or only slightly marked with concentric lamellose 

 lines upon the body of the shell, the auricular extensions usually 



