MOLLUSCA. 775 



Volutoderma biplicata (Gabb). 

 Plate XCL, Figs. 13-17. 



1860. Volutilithes biplicata Gabb, Jour. Acad. Nat. Sci. Phil., 



2d sen, vol. 4, p. 300, pi. 48, fig. 6. 



1861. Volutilithes biplicata Gabb, Synop. Moll. Cret. Form., 



P- H9 (93)- 

 1864. Rostellites biplicata Meek, Check List. Inv. Foss. N. A., 



Cret. and Jur., p. 21. 



1868. Rostellites biplicatus Con., Cook's Geol. N. J., p. 729. 

 1876. Volutoderma biplicata Gabb, Proc. Acad. Nat. Sci. Phil. 



(1876), p. 292. 

 1892. Volutoderma biplicata Whitf., Pal. N. J., vol. 2 (Monog. 



U. S. G. S., vol. 1 8), p. 90, pi. 10, figs. 1-2. 

 1905. Volwtoderma biplicata Johns., Proc. Acad. Nat. Sci. 



Phil. (1905), p. 25. 



Description. "Shell of medium size, robust, pyriform in out- 

 line, with a low spire and very large body volution; whorls 

 three to four, ventricose, largest above the middle and narrowed 

 below; aperture very large, elongate, two^thirds the length of 

 the shell and semielliptical, straightened on the inner side and 

 rounded on the outer margin; columella strong, marked by two 

 strong oblique folds near the middle of its length.; surface 

 unknown, but on the inner volution of the type and on a smaller 

 specimen in the collection Am. Mus. Nat. Hist., N. Y. City, 

 there are a few distant vertical plications, faintly indicated, but 

 which do not extend below the most ventricose part of the 

 whorl." (Whitfield.) 



Remarks. A careful examination of the lithologic characters 

 of the type of this species has led to the conclusion that it came 

 originally from the Merchantville clay-marl. In the recent col- 

 lections of the Survey it has been observed most commonly in 

 the 'Merchantville, but it also occurs rarely in the Wenonah 

 sand. 



Formation and locality. Merchantville clay-marl, Lenola 

 (163); Woodbury clay, near Matawan (103); Marshalltown 



