350 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



proper columella, and the characteristic external sulcus, as well as the callous 

 inner lip of that genus, readily distinguish it. 



Our type-species came from the Upper Cretaceous; but I am unac- 

 quainted with any other species from that or any older formation, or even 

 from the Tertiary rocks. A single existing species, however, so nearly resem- 

 bles our type, that I am rather inclined to believe it congeneric. Tins is a 

 shell described by Middendorff, from the Great Schantar Isle, under the 

 name Bullla ampidlacea (see Sibirische Reise, tab. xvii, figs. 1-3). Through 

 the kindness of Dr. Stimpson, I once had an opportunity to examine a speci- 

 men of Middendorff's species. It has a much less arcuate and tortuous inner 

 lip (columella?) than our shell, and is not nearly so strongly striated; but in 

 other respects it presents many points of resemblance. It has a thin epider- 

 mis, with numerous short hair-like filaments along the lines of growth. Its 

 operculum is very small, or merely rudimentary, with its nucleus terminal, 

 instead of submarginal and lateral, as in Buccinum. Its tentacles are short 

 and the eyes at their outer bases; and its foot is ovate and broadest in front, 

 where it is double-edged. Dr. Stimpson ascertained that its lingual dentition 

 is as in Buccinum. 



Whether Middendorff's shell ought to be admitted into our genus or not, 

 there may be different opinions ; but I think no one will now maintain that 

 it belongs to the. genus Bullia. 



Pscudobiicciiiiini Nebrascense, M. & H. 



Plate 31, figs. 5, a, b, c, <L 



Buccinum^ Nebrascense, Meek and Hayden (1856), Proceed. Acad. Nat. Sci. Pbilad., VIII, 67. 

 Pseudohuccinum Nebrascensc, Meek aud Hayden (1857), ib., IX, 140. — Meek (1864), Smithsonian Check- 

 List N. Am. Cret. Fossils, 22. 



Shell rhombic-oval ; spire rising little above the body-volution ; whorls 

 three and a half, convex, rapidly increasing in size, last one forming nine- 

 tenths of the entire bulk, evenly rounded ; suture slightly channeled ; surface 

 showing rather distinct lines of growth, with the little revolving, impressed 

 lines separated by spaces of nearly the same breadth on the lower half of 

 the body- volution, but more distant above, where they are less strongly 

 marked ; aperture rhombic-oval, about four-fifths the length of the entire shell, 

 widest at the middle, angular above, and a little truncated at the sinus below; 

 outline of the thin outer lip slightly convex along its entire length ; reflexed 

 inner lip widesl where it is thinly appressed upon the tortuous, deeply arcuate. 



