140 PROCEEDINGS OP THE ACADEMY OF 



prominent near the middle, and having a broad faint sinus above ; colnmella 

 slightly arcuate. Length about 1'42 inches; breadth -67 inch; apical angle 

 very convex, divergence 40". 



Not having seen a specimen of this species showing very clearly the form of 

 the outer lip, we are left in some doubt as to whether it is not more nearly re- 

 lated to Pleurotoma than Fusus. The lines of growth, are so deflected below 

 the suture, as to indicate the presence of a broad faint sinus in the upper edge 

 of the lip, as in Pleurotoma ; the general aspect of the shell, however, is more 

 like Fusus than Pleurotoma. It is probably one of those connecting links be- 

 tween those genera, often met with amongst fossil species. None of our speci- 

 mens show the entire length of the canal, but we are inclined to think it was not 

 very long. 



There is no other shell in the Nebraska formation No. 5 known to us, resembling 

 this in other respects, that has so remarkably convex a spiral angle, the con- 

 vergence from the first to the second volution being only about 30**, while the 

 angle at the apex is as much as 48°. 



We have named this species in honor of .Mr. George Scarborough, of Owens- 

 boro', Ky., a quiet but devoted cultivator of natural science. 



Locality and position. Butte aux Gres, on the Missouri River, formation No. 5 

 of the section. 



New Gen. PSEUDOBUCCINUM. 



Owing to the fact that the limits of the great genus Buccinum are badly defined, 

 and several attempts have already been made to erect into distinct genera, forms 

 regarded by many of the ablest conchologists as merely sections of that genus, 

 it is with hesitation we venture to propose for a shell of this type a new generic 

 name. Although evidently related to Buccinum, the species before us presents, we 

 think, an ensemble of characters of sufficient importance to be regarded as the 

 type of a distinct group. In the first place, it differs remarkably from the species 

 of that genus known to us, in the deeply arcuate and strongly tortuous charac- 

 ter of its columella, as well as in the comparatively large size of the body volu- 

 tion and aperture. So distinctly marked are these characters, that it appears 

 probable, if the matrix were removed from the inside of the shell, the whole 

 interior, quite to the apex of the spire, would be visible from below. It like- 

 wise differs from any of the species of Buccinum coming under our observation, 

 in being a much thinner shell, and in having, instead of a short reflexed canal 

 or deep notch at the base of the columella, simply a small rounded sinus. 



In form and general appearance it resembles Sulcobuccinum of D'Orbigny, and 

 Pseudoliva, of Swainson ; but differs from them both in its strongly arcuate and 

 tortuous columella, as well as in wanting the revolving sulcus on the exterior 

 of the body whorl. It is also a much thinner shell than we have seen amongst 

 the species of either of these types, and wants the small notch in the outer lip, 

 characteristic of the first, and the projecting spine on the inner side of the same 

 in the other. 



As it is not possible to give definitely the characters of a genus, of which but 

 a single species is known, we will for the present merely repeat a description 

 given on a former occasion of this shell, without attempting to separate the 

 specific characters from those that may be only of specific importance. 



^ PSEUDOBUCCINUM NeBRASCENSIS. 



Buccinum? Nebrascensis, 31. <j- 17., Proceed. Acad. Nat. Sci. Vol. 8, p. 61. 

 Shell oval, thin; spire very short ; volutions three to three and a half, convex, 

 rapidly increasing from the apex, last one very large and somewhat ventricose ; 

 surface marked with distinct lines of growth, which are crossed by flattened 

 revolving bands, much wider on the upper part of the volutions than the shal- 

 low grooves between, but about equalling them on the lower part of the last 

 turn. About seven or eight of these bands may be counted on the second vo- 

 lution ; suture narrow and slightly channeled ; aperture large, subelliptical. 



[May^ 



