126 PALEONTOLOGY OF NEW JERSEY. 
1s inches by a height of about 14 inches.. The species differs from G. 
petrosa in its greater size, more robust volutions, which are not so much 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. abyssinus 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 Mullica Hill, New Jersey. 
GYRODES CRENATA, 
Plate xvi, Figs. 5, 6. 
Natica (Gyrodes) crenata Conrad: Jour. Acad. Nat. Sci., Phila., 2d 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 perceptibly 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 forms 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 flattenmg 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 by pressure. ‘They closely resemble in form G. petrosa Morton, but 
