90 PALEONTOLOGY OF IStEVV JERSEY, 



and shown its near relations to Piesfochihis Meek. Thei'e is often some 

 difficulty in distinguishing between the internal casts of Volutomorpha and 

 those properly referable to Voliitodenuu. This latter genus appears to me 

 to belong properl}- to the VolatidcB, as referred by the author, on account 

 of the form, number, and position of the columellar plaits, and also on 

 account of the form of the anterior portion of the shell itself As stated 

 under the remarks upon Peistocliilus and Volutomorpha on p. 70, the shells 

 of this latter genus are characterized by the narrow anterior canal and 

 beak, by the very oblique columellar folds, and by the enlarged upper 

 part of the volutions; while those of Volutodernia are characterized by the 

 more ventricose volutions, shorter spire, broader base, and short open canal ; 

 by having usually a larger number of less oblique and generally stronger 

 columellar folds than in the other genus. The surface markings, so far as 

 known from New Jersey specimens, are alike in the two genera. In many 

 cases where imperfect examples of internal casts have to be examined of 

 forms like Volutomorpha pondcrosa, where the nearly equally tapering upper 

 and lower parts of the specimen occur, with a broad anterior canal and 

 very ventricose volutions, it is quite difficult to determine satisfactorily to 

 which genus they belong, unless one can find evidence of the plications, 

 for in this case the front of the shell has not been prolonged very much, 

 and consequently seems to form a link between the two genera. On close 

 inspection, however, it will be seen that the spire is more elongated even 

 in this species than in any yet authentic form of Volutoderma. The follow- 

 ing species I have placed under this latter genus. 



Volutoderma biplicata. 

 Plate X, Figs. 1, 2. 



Volutilithes biplicata Gabb: Jour. Acad. Nat. Sci., PMla., 2d ser., vol. 4, p. 300, 



PL XLViil, Fig. 6; Synopsis, p. 93. 

 Rostellites biplicata Meek, Check List Cret. and Jur. Foss., p. 21 ; Geol. N. J., 



Newark, 1868, p. 729. 

 Volutoderma biplicata Gabb: Proc. Acad. Nat. Sci., Phila., 1876, p. 292. 



Shell of medium size, robust, pyriform in outline, with a low spire and 

 very large body volution; whorls three to four, ventricose, largest above 



