124 PALEONTOLOGY OF NEW JERSEY. 



The species was originally described from Prairie Bluff, Alabama, where 

 the specimens are of large size and .sometimes show evidences of the shell, 

 which must have been of considerable tliickness, as they are frequently seen 

 to have been perforated by a boring sponge. The New Jersey casts differ 

 from those of G. infracanilta Gabb, with which this species is iisually con- 

 founded, in being less oblique, more erect, lower in the spire, the volutions 

 rounder and not carinate on the edge of the wide umbilicus. The evidence 

 of its relations to the genus Gyrodes is not very strong. 



Formation and lovaUtij : In the ferruginous layers of the Lower Marls 

 at Mullica Hill, and near Burlington, New Jersey, not a very common 

 species; also from the same position at Tinton Falls, New Jersey. Col- 

 lection at Columbia College. 



Genus GYEODES Conrad. 



Gyrodes Abbottii. 



Plate XV, Fig. 17. 



Gyrodes Abbottii Gabb : Proc. Acad. Nat. Sci., Phila., 1861, p. 330 ; Meek, Check 

 ListCret. and Jur. Foss., p. 21 ; Geol. N. J., Newark, 1868, p. 729. 



This species was described by Mr. Gabb from a single individual cast, 

 which retains around the summit of the outer volution remains of markings 

 which present the appearance of a series of undulations, or "oblique plica- 

 tions," having a backward direction in their passage from the suture line 

 across the body of the shell. Aside from these markings there is not the 

 slightest difference between this and the ordinary casts of G. ahyssinus Mor- 

 ton, either in form or bulk. The specimen is preserved in a ferruginous 

 gravel or very coarse iron sand, which fills the sutures and umbilical cavity, 

 and to a considerable extent obscures these features ; so that a strict com- 

 parison is not possible without changing its appearance by clearing away the 

 adhering material. This I have not ventured to do, as the specimen is the 

 property of the Acad. Nat. Sci., Phila., and the change would destroy the 

 features upon which the author of the species founded it, which I do not 

 consider I have the right to do. I do not think, however, the species is a 

 valid one, but regard it as only an accidental form of Gyrodes ahyssinus. If 

 the adhering material were cleaned away, I think the cast beneath would 



