352 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



middle of the aperture. I have not seen any examples with the edge of the 

 outer lip entire ; but it is evident, from the curves of the lines of growth, 

 as seen by the aid of a magnifier, crossing the revolving sulcus mentioned 

 above, that there is, in entire specimens, a small, pointed, tooth-like process 

 at the lower termination of the sulcus, somewhat similar to that of the genera 

 Chorus, Acanthina, Pseudoliva, and some other types. It differs, however, 

 from all of these in having the tooth situated directly at the lower angle of 

 the outer lip, instead of above it, and in the presence of plaits on the col- 

 umella, as well as in other obvious characters, such as the smooth surface, 

 thickened inner lip, and wider notch below, of Pseudoliva; the different 

 nature of the canal, surface-characters, &c, of Chorus ; the position of the 

 tooth within the margin of the lip, and the crenate character of the same in 

 Acanthina, &c. 



In form, ornamentation, and the plaits on the columella, this type also 

 very nearly resembles some little shells described by me, from the Cretaceous 

 rocks at Coalville, Utah, in Dr. Hayden's Sixth Annual Report of the United 

 States Geological Survey of the Territories, under the names Admetel rhom- 

 boides, A.X gregaria, and A.I suhfusiformis. These were only referred to 

 Admete with great doubt, however, and the provisional name Admetopsis was 

 suggested for them, in case good characters should be found for the establish- 

 ment of a distinct group for their reception. Notwithstanding the close general 

 resemblance of these shells, however, to the type of the genus here proposed, 

 no traces of the revolving sulcus and little tooth at its termination, which 

 form the most marked characters of the latter, are to be seen in any of them; 

 and consequently they could not be properly placed in the same genus. 



So far as known, this would seem to be an exclusively Cretaceous group. 



Odontobasis con strict a, H. & M. (sp.). 



Fkrus a>nslrictus, Hall and Meek (1656), Meru. Am. Acad. Arts and Sci., V, 391, pi. iii, tigs. 7, a,b,c,d 



(removed to Buccinum, ib., 411). 

 Biiccinumt constrictum, Meek aud Hayden (1856), Proceed. Acad. Nat. Sci. Pliilad., VIII, 283. — Meek 



(1864), Check-List N. Am. Cret. Fossils. 22. 



Shell subfusiform, with spire equaling about two-thirds the length of the 

 aperture and canal ; volutions four or five, convex, and each ornamented with 

 about eleven comparatively strong, rounded, vertical folds, equaling the 

 depressions between ; last turn moderately convex around the middle, some- 

 what constricted above, and tapering into the beak below ; suture linear, and 



