MOLLUSCA. 781 



or convex in the upper part, and prolonged and attenuated below, 

 forming a long, gracefully tapered anterior beak with the 

 columella slightly twisted; top of the volution rather suddenly 

 contracted to the suture; aperture large, very elongate-elliptical 

 in outline and prolonged below, where it becomes narrowed as 

 the outer lip approaches the axis; columella slightly twisted and 

 marked by from one to three very oblique folds, the middle one 

 of which is usually the strongest; surface of the casts usually 

 smooth, with the exception of, in some cases only, a few distant 

 vertical folds on the upper ones, and on the extreme upper part 

 of the body volution; but where the external features are pre- 

 served, the whole shell is marked by strong, rounded, vertical 

 folds, and but little less strongly marked, rounded, spiral ridges; 

 the spiral ridges moderately distant on the upper part of the 

 volution, but becoming less strongly marked and crowded, and 

 finally almost obsolete, toward the base." (Whitfield.) 



Remarks. More or less imperfect casts of this species are not 

 infrequently met with in collections from the Navesink marl of 

 New Jersey. A careful comparison of the types of the two species 

 V . conradi and V . gabbi, shows the two forms to be too closely 

 alike to be regarded as specifically different. The separation 

 of the two supposed specific forms by Whitfield was based 

 almost entirely upon the more robust form and the squarer 

 shoulder of V . gabbi, but an examination of numerous examples, 

 all from the same horizon, shows the two forms to be only 

 extreme individual variations of a common species. 



Formation and locality. Cliffwood clay, Cliffwood Point 

 (103); Navesink marl, Atlantic Highlands (108), near Free- 

 hold (133), near Walnford (i48 2 ) Cross wicks Creek (i47 4 ), 

 near Jacobstown (150), near Mount Laurel (166), Miullica Hill 

 (i69 2 ), Holmdel (Whitfield). 



Geographic distribution. New Jersey. 



Volutomorpha ponderosa Whitfield. 

 Plate XCV., Figs. 1-2. 



1892. Volutomorpha ponderosa Whitf., Pal. N. J., vol. 2 

 (Monog. U. S. G. S., vol. 18), p. 72, pi. 8, figs. 5-6; 

 pi. 9, figs. 13-15. 



