GASTEROPODA OF THE LOWER GEEEN MARLS. 123 



even this may be distinguished by the larger cavity left by the removal of 

 the columella, and b}' the greater thickness or strength of the beak. The 

 spiral ridges on this one are also more numerous and more sharply ele- 

 vated, while the decided alternation of siiie among them will ser\e as a 

 distinguishing feature. There is so great a similarity between this and 

 many Tertiary forms of the genus that I shall not attempt to institute com- 

 parison between them, as they would be useless as distinguishing features, 

 and I know of no Cretaceous species resembling it. 



Formation and locality: In the marls of the Lower Beds at Holmdel, 

 New Jersey. From Dr. Reiley's collections. The maid in which it occurs 

 is of a ferruginous white color resembling some of the limestone nodules 

 from the Lower Marls. 



NATICID^. 



Genus NATICA Lamarck. 



Natica abyssina. 



Plate XV, Figs. 9-13. 



Natiea abyssina Morton : Syn. Org. Rem. Cret. , p. 49, PI. xiii, Fig. 13. 

 Oyrodes abyssina (Mort. ) Gabb : Synopsis, p. 59 ; Proc. Acad. Nat. Sci. , Phila. , 

 1876, p. 295. 



Shell large, globose, with a flattened spire, the inner volutions of which 

 scarcely rise above the outer ones, and are only two and a half to three in 

 number; volutions rather ventricose and erect, ovate in a transverse sec- 

 tion; umbilicus large and open to near the apex of the shell; aperture 

 ovate, two-thirds as wide as long, and a little more convex on the outside 

 than on the inner margin, nearly equally rounded above and below; suture 

 well marked and deeply impressed. 



The species is represented only by casts in the New Jersey localities, 

 so that the features of the surface are not known from within the State. 

 Mr. Gabb cites it as coming from Patula Creek, Georgia, where, he says, the 

 surface shell is preserved, but that it is perfectly plain. A single cast which 

 I have seen from New Jersey showed a deposit of ocher in the umbilicus 

 which appeared to represent, the thickness of the shell in that part. It was 

 exceedingly thin and showed no callus or other feature of thickening. 



