366 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



subovate; surface with the vertical flexnoiis costse each terminating at the 

 outer edge of the furrow or constriction below the suture, in a small node; 

 those on the volutions of the spire distinctly defined, rounded, and separated 

 by furrows of the same size, while toward the aperture on the body-volution, 

 they all become less strongly defined ; lines of growth fine, but rather distinct, 

 and crossed by fine, closely-arranged, revolving striae, which, like the lines 

 of growth, become somewhat stronger and less regular on the lower part of 

 the body-volution. 



Length, about ^.40 inches; breadth of body-volution, about 1 inch. 

 Spire with nearly straight slopes, diverging at an angle of 57°. 



The generic relations of this shell have long been in doubt; though I 

 never felt satisfied with its reference to the genus Gladius (= Rostellaria). 

 I had frequently very carefully examined its columella by cutting away the 

 rock filling the aperture of the only specimen we have, far enough to show 

 that it seemed entirely destitute of plaits.- Noticing, however, some more or 

 less nearly similar foreign species, in which broken specimens had shown the 

 existence of plaits far around the columella within the aperture, I was led to 

 cut away the rock still farther around the columella, and at last discovered 

 that it bears one very oblique, linear plait, somewhat below the middle of the 

 aperture. Consequently, it became at once evident, that this shell has no 

 near relations to Rostellaria, but that, like the foregoing species, it must find 

 a place in or near the genus Fasciolaria ; though it and the following species 

 present sufficiently marked differences to be placed in a separate, subgenus 

 at least. 



As the only specimen we have for study is less nearly complete than the 

 original typical one, I have preferred to copy the published figure of the latter, 

 rather than figure an inferior example of the species; but our specimens are 

 well enough preserved to leave no doubt that they are specifically identical. 



I know of no described foreign species so near this as to require a 

 critical comparison; though some of those figured by Dr. Stoliczka from the 

 Cretaceous rocks of India, are at least apparently members of the same 

 subgenus. 



« 



Locality run/ position. — The original typical specimen of this species 

 came from Sage ('reek, Dakota, near the Bad Lands; from the upper part 

 of the Fort Pierre Group Others before me came from about the same 

 horizon on the South Fork of Cheyenne River, near the Black Hills. 



