126 PALEONTOLOGY OF NEW JERSEY. 



1 finches by a height of about 1^ niches. The species differs from G. 

 jx'trosa in its greater size, more robust volutions, which are not so nmch flat- 

 tened on the upper half, thereby giving a rounder and less oblique form. 

 The umbilicus is also larger in proportion and the shell more angular on its 

 lower margin. It differs from G. ahyssmus Morton in being less erect or 

 more oblique, and in the angularity of the margin of the umbilicus. 



Formation and locality : It is found in the Lower Marls near Burlington, 

 and at MuUica Hill, New Jersey. 



Gykodes crbnata. 



Plate XVI, Figs. 6, 6. 



Natica (Gyrodes) crenata Conrad: Jour. Acad. Nat. Sci., Phila., 3d ser., vol. 4, 



p. 289. 

 Gyrodes crenata (Conrad) Gabb: Synopsis, p. 60; Meek, Check List Cret. and Jur. 



Foss., p. 21. 



Shell below a medium size, broadly patulose in form, with a depressed 

 spire and a very broad open umbilicus; volutions four or five, obliquely 

 spreading and subangular below; inner whorls scarcely raised above the 

 outer one, but very percej)tibly distinct from the effects of a band of elevated 

 crenulations or transverse nodes which marks the top of the volutions just 

 below the suture line and fonns a very decided ridge around the spiral por- 

 tion of the shell, rendering the different volutions easily distinguishable; 

 the broad umbilicus, limited below by a narrow, elevated, rounded ridge at 

 the base of the volution, is also marked within by a less distinct carina 

 a little below the middle of its depth; aperture oblique, truncated above by 

 the flattening of the volution between the suture and the line of nodes 

 which marks the volutions, and somewhat angular below; the angulation 

 corresponding to the position of the rounded carina-like ridge at the base , 

 of the volution; surface of the shell marked by fine lines of growth corre- 

 sponding to the margin of the aperture and passing over the line of nodes 

 on the upper surface of the volution. 



The specimens of this species which I have seen do not exceed seven- 

 eighths of an inch in their greatest diameter, and all are more or less dis- 

 torted liy pressure. They closely resemble in form G. petrosa Morton, but 



