MOLLUSCA. 795 



1868. Turbinopsis depressus Con., Cook's Geol. N. J., p. 729. 

 1905. Turbinopsis depressa Johns., Proc. Acad. Nat. Sci. Phil. 



(1905), p. 26. 

 1892. Modulus lapidosa Whitf., Pal. N. J., vol. 2 (Monog. U. 



S. G. S., vol. 18), p. 152, pi. 17, figs 6-8. 

 1905. Turbinopsis lapidosa Johns., Proc. Acad. Nat. Sci. Phil. 



(1905), p. 26. 



Description. The dimensions of one of the specimens, an 

 internal cast, are: height, 14 mm.; maximum diameter of the 

 outer volution, 14 mm. Shell broadly umbilicate, with two or 

 three volutions, spire depressed, suture about flush with the sur- 

 face. Outer volution gibbous, its greatest width above the middle, 

 periphery rounded, the upper and lower surfaces both convex, 

 the slope of the upper surface to the suture more abrupt than the 

 slope of the lower surface, contracted below to a very short an- 

 terior canal. Surface of the outer volution marked with revolv- 

 ing costss, probably about seven or eight in number, and by 

 transverse ribs of about equal strength, with interspaces about 

 equal to those between the revolving costae; the points of inter- 

 section of the revolving and transverse ribs are elevated into low 

 nodes. Internal casts smooth or marked by more or less in- 

 distinct revolving ribs, the surface rounded from the suture to 

 the angular umbilical margin, the greatest thickness of the volu- 

 tion about its mid-height; columellar cavity very broad, marked 

 by a single strong and sharp revolving fold situated near the 

 -anterior margin. 



Remarks. This species usually occurs in the condition of 

 internal casts, but at one locality in the Wenonah sand impres- 

 sions of the exterior have been collected which show the character 

 of the external surface markings of the shell. There seems to 

 be no essential difference between the shell which Whitfield 

 described as Modulus lapidosus and the type of Turbinopsis 

 depressus. Whitfield's specimen exhibits the revolving ribs upon 

 the cast somewhat more clearly, and the spire is a little more 

 depressed than Gabb's type, but these differences can be con- 

 sidered as nothing greater than individual varieties, certainly not 

 of specific importance. 



