GASTEROPODA OP THE LOWEE GREEN MARLS. 81 



Formation and locality: In a blackish layer of the Lower Green Marls 

 in Monmouth County, New Jersey, the exact locality not known. Collec- 

 tion Acad. Nat. Sci., Phila. 



TURBINELLA ? SUBCONICA. 

 Plate IX, Figs. 7, 8. 



Turbinella subconica Gabb: Proc. Acad. Nat. Sci., Phila., 1860, p. 94, PI. ii. Fig. 



6; Synopsis, p. 86; Meek, Check List Cret. and Jur. Foss., p. 31. 

 Turbinella? subconica (Gabb) Meek: Geol. N. J., Newark, 1868, p. 730. 



Shell rather below a medium size, the cast measuring only about 1 

 inch in height, with a transverse diameter somewhat less; form turbinate, 

 with a very low spire, consisting of not more than three volutions in the 

 only specimen known; volutions ventricose, obconical, scarcely rounded on 

 the upper margin, but rapidly narrowing below and rounded on the side; 

 aperture large, almost semilunate, or only very slightly convex on the inner 

 margin; columella strong, marked by two very distinct plications at the 

 lower third of the aperture, the lower one being distinctly the stronger of 

 the two; sutures between the whorls of the cast very large, indicating a 

 thick, heavy shell; surface as shown on the inside of the body whorl of the 

 cast marked by strong spiral lines or ridges, and by remarkably strong 

 vertical folds, numbering twelve or thirteen on the last volution, and trans- 

 mitting their features only very slightly to the internal cast at the point of 

 greatest diameter, but showing on the inside as above stated for more than 

 half its depth. 



This species has very much the appearance, in its condition as an 

 internal cast, of a species of Rapa, but the columellar cavity is rather small 

 for that genus. The plications on the columella, however, about which 

 there is no shadow of doubt, at once remove it from that group and mark 

 it as belonging to the Turhinellidce. Mr. Gabb's figure given in Proc. Acad. 

 Nat. Sci., Phila., as above cited, is very poor, and much smaller than the 

 type and only specimen, a figure of which is given full size anTl enlarged 

 on our plate. 



Formation and locality: In dark ferruginous marls from the Lower 

 Greensands in Monmouth County, New Jersey. The definite locality not 

 known. Collection Acad. Nat. Sci., Phila, 



/ 



MON XVIII 6 



