MOLLUSCA. 391 



differs from A r . conradi, which is the most nearly related mem- 

 ber of the genus in the New Jersey faunas, in its more nearly 

 obsolete radiating surface markings, its more rounded umbonal 

 ridge, and usually in its larger size. 



Formation and locality. Cliffwood clay, Cliffwood Point 

 (105); Wenonah sand, near Marlboro (130), near Crawfords 

 Corners ? (i26 3 ). 



Geographic distribution,, New Jersey, North Carolina, 

 Mississippi. 



Genus CUCULLAEA Lamark. 



Cucullaea antrosa Morton. 

 Plate XXXII., Figs. 7-9. 



1834. Cucullcca antrosa Mort, Synop. Org. Rem. Cret. Gr. U. 



S., p. 65, pi. 13, fig. 6. 

 1 86 1. Cucullaea antrosa Gabb, Synop. Moll. Cret. Form., p. 172 



(116). 

 1864. Cucullcea antrosa Meek, Check List Inv. Foss. N. A., 



Cret. and Jur., p. 8. 



1868. Idonearca antrosa Con., Cook's Geol. N. J., p. 725. 

 1872. Idonearca antrosa Con., Proc. Acacl. Nat. Sci. Phil. 



(1872), p. 54. 

 1876. ? Idonearca antrosa Gabb, Proc. Acad. Nat. Sci. Phil. 



(1876), p. 315. 

 1886. Idonearca antrosa Whitf., Pal. N. J., vol i (Monog. U. 



S. G. S., vol. 9), p. 96, pi. 13, figs. 6-1 1 

 1905. Cucullaea antrosa Johns., Proc. Acad. Nat. Sci. Phil. 



(1905), p. '8. 



Description. "Shell subcircular in outline, or very slightly 

 ovate from being a little prolonged at the postero^-basal angle, 

 very slightly oblique with a straight hinge line, which is about 

 half as long as the greatest length of the shell. Beaks large, 

 erect, and slightly incurved, but not projecting beyond the edge 

 of the proportionally small ligamental area which is marked by 

 oblique grooves, as in all species of the group. Surface of the 



