92 L. Agassiz on the Ichthyological Fauna of Western America. 
mens to Paris from the Wabash, the labels of which seem to have 
been lost; at least Valenciennes, who describes them as Cat. 
planiceps, says he received them from Lesueur without a name, 
not recognising that they were original specimens of the Catost. 
nigricans of Lesueur, as the description of Valenciennes clearly 
shows them to be. Hylomyzon nigricans has the widest geo- 
graphical distribution of all our Catostomi. It occurs in the 
northern and middle Atlantic States, in all the great Canadian 
Lakes, with the exception of Lake Superior, through all the mid- 
dle western States as far as Missouri. Its southernmost localities 
are Lebanon, Tennessee, from which place I have received speci- 
mens — Prof. J. M. Safford, and Huntsville, Alabama, 
. H. Newman, Esq., sent me also several specimens. 
Its ra cnet range is in the Osage River, Missouri, from 
which Mr. G. Stolley has sent me quite a number. I have 
repeatedly aud most carefully compared with one another the 
specimens from the remotest then without finding the least 
specific differeuce between t 
Catostomus. 
I have retained the name of ae for the type to which 
it was originally applied by For 
e body is elongated, {emai ae slightly compressed. The 
snout is short and blunt, and projects but little beyond the mouth, 
which is inferior. 
The lower jaw is short and broad; the lips are fleshy and 
dames bilobed below ; their surface is conspicuously granulated 
or papillated. The head is considerably longer than high. The 
dorsal is large, and mostly in advance of the ventrals; its length 
is greater than its height. The anal fin is long and slender, and 
reaches the caudal. 
The sexual differences so conspicuous in the genus Moxostoma 
and Ptychostomus, are hardly to be noticed in-this genus. The 
other fins are of moderate size, and more or less pointed. 
The scales are much smaller on the anterior than on the pos- 
terior portion of the body; nearly quadrangular, with rounded 
angles, but somewhat longer than high; the ornamental concen- 
tric ridges of the posterior field broader than those of the lateral 
_and anterior fields; the radiating furrows more numerous than in 
Hylomyzon and Ptychostomus, and encroaching upon the lateral 
fields, where in some species, they are nearly as numerous, as 
upon the anterior and posterior fields. ‘Tubes of the lateral line 
wider than in Hylomyzon and Ptychostomus, extending from 
the centre of radiation to the posterior margin. 
The pharyngeals are stout and compact, ri outer margin not 
ea Pi as in Ptychostomus; the teeth are blunter and larger 
tively than in ey other genus of ine tribe, increasing 
