788 CRETACEOUS PALEONTOLOGY. 



nearly one-half the length, and abruptly contracted below, form- 

 ing an undefined angle a little above the middle of the length of 

 the volution, and extended below into a more or less slender 

 columella; aperture narrow and pointed above, broad and some- 

 what effuse below ; columella marked by four strong oblique folds, 

 the lower one of which is more distant from the next above than 

 are the others from each other; surface features unknown." 

 (Whitfield.) 



Formation and locality. — Navesink marl, Atlantic Highlands 

 (io8). 



Geographic distribution. — New Jersey. 



Rostellites biconicus Whitfield. 



Plate XCVIL, Figs. 5-8. 



1892. Rostellites biconicus Whitf., Pal. N. J., vol. 2 (Monog. 

 U. S. G. S., vol. 18), p. 183, pi. 23, figs. loii. 



Description. — "Shell moderately elongated, as seen in the con- 

 ditions of internal casts, the only condition in which it is at 

 present known. Spire elevated, consisting of about four or five 

 volutions, the aperture, which is narrow, forming about two- 

 fifths of the length of the entire cast. Volutions moderately con- 

 vex, largest at or near the upper margin, indicating something of 

 a square, shoulder-like upper surface for the perfect shell ; below 

 this angulation the upper volutions are slightly convex, and in the 

 casts leaving very deep and strong sutures between the different 

 whorls of the spire. Lower volution distinctly largest above and 

 cone-like in shape, with a short columellar projection below; the 

 lower half of the volution being more rapidly tapering than the 

 upper, forms a slight angulation just below the middle. Colu- 

 mella strong and marked by four nearly equidistant oblique folds, 

 the lower one of which is not more than once and a half as far 

 from the base as the distance between each fold. Aperture very 

 narrow, pointed above and below ; surface, as far as can be seen 

 on the internal casts, showing nO' evidence of longitudinal folds 

 or revolving lines ; but the shell having been quite thick may not 



