326 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



of the expanded lip, where they spread more widely apart, and sometimes 

 have an intermediate smaller one intercalated between. The expanded lip is 

 strengthened by the upper carina of the body-volution being continued along 

 the middle all the way to its mucronate, upcurved point. On its inner side, 

 there is a furrow corresponding to the external carina; but this furrow is not 

 well represented in our figure 8 a, of plate 32. 



I know of no described species with which this is liable to be 

 confounded. 



Locality and position. — Moreau River, Long Lake, and other localities ; 

 in the Fox Hills group of the Upper Missouri Cretaceous series ; also, on the 

 Yellowstone River, in beds containing a mingling of the fossils of that and 

 the Fort Pierre groups. 



Anctanra (Drcpanochilus) rVchrasceiisis, E. & S. (sp.). 



Plate 19, figs. 5, a, b, c. 



JlostcJlaria Nebrasctnsis, Evans and Shuniard (1854), Proceed. Acad. Nai. Sci. Philad., VI, 164. 

 Aporrhaw Nebrascensis, Meek & Hayden (1860), ib., XII, 423.— Gabb (1861), Synon. Moll. Cret. Form., :.'.!. 

 Anchura ( Drrpaiiudiilua) Xcbrascerisis, Meek (1864), Smithsonian Cueck-List N. Am. Cret. Fossils, 19. 



Shell small, irregularly subfusiform; spire acutely conical, about equaling 

 the length of the body-volution and beak ; volutions six and a half to seven, 

 convex, and separated by a distinct suture, last one flattened on the oblique 

 upper slope, unequally bicarinate around the middle, and abruptly contracting 

 below into the short mucronate beak; upper carina of the body-volution 

 more prominent than the lower, and continued along the labial extension 

 to its extremity ; surface ornamented by numerous small, strongly Hexuous, 

 vertical costje, that become obsolete on the body-volution, and very tine, 

 regular, closely-arranged, revolving lines, which are less closely arranged as 

 they pass upon the extended lip, and on the lower part of the body-volution, 

 where they usually show an intermediate, much smaller, series; outer li[> 

 equaling, at its commencement, the breadth of the body-volution, but very 

 rapidly narrowed by the nearly straight, obliquely ascending, lower margin, 

 and the broadly sinuous outline of the upper, so as to form a single slender, 

 mucronate, slightly backward-curved process ; aperture unknown. 



Length, about 0.52 inch; breadth of body-volution, exclusive of the 

 extended lip, 0.23 inch ; slopes of spire a little convex, with a divergence 

 from the apex of about 20°. 



This species resembles the last in general appearance and surfaced 



