L. Agassiz on the Ichthyological Fauna of Western America. 81 
The eye is small, and the opercular pieces very large. 
The scales have many narrow radiating furrows upon the an- 
terior field ; none across the lateral fields, few upon the margin of 
the posterior field and these not extending to the centre of radia- 
tion. Tubes of the lateral line straight and simple, arising nearly 
in the middle of the posterior field. 
The pharyngeal bones are neither flat, as in the Carpiodes, nor 
triangular as in Bubalichthys, but present an intermediate form ; 
the outer surface of the arch standing outwards, and presenting a 
porous outer margin. The peduncle of the symphysis is much 
longer proportionally and more pointed than in Carpiodes and 
Bubalichthys. The teeth are very numerous, small, thin and 
compressed as in Carpiodes, but the lower ones are gradually 
larger than the upper ones. Their inner edge is slanting out- 
wards, and not uniformly arched as in Bubalichthys, or truncate 
as in Cycleptus, the innermost margin rising somewhat in the 
shape of a projecting cusp. 
ig. 3, a, represents the right pha- 
ryngeal of [chthyobus Rauchii, from 
the inner side, 6 and 6’ lower teeth 
from both sides, ¢ a tooth from the 
middle of the comb, and d, one from 
its upper end. 
Thus far a single species of this 
genus has been accurately described 
by Valenciennes, under the name of 
Sclerognathus Cyprinella, from lake 
Pontchartrain, near New Orleans; but 
as I have remarked above, the genus Sclerognathus ean not stand, 
since it includes two distinet types, for*both of which Rafinesque 
has already introduced unobjectionable names. One of these 
genera is founded upon the Catostomus Cyprinus of Lesueur, and 
will retain the name of Carpiodes, as characterised above, the _ 
yin is the subject of this paragraph, for which the name of 
c 
all other fins much larger, and the scales not higher than long; 
from Burlington, Iowa. Received from Dr. Rauch, to whom [ 
am indebted for a very large collection of fishes from the Missis- 
Sipp!, and its tributaries in the State of Iowa. : 
Ichthyobus Stolleyi.—Body higher than in Ichthyobus Rauchii, 
Profile steeper, and hence snout blunter, opercular bones larger, 
fins proportionally of the same size. From Osage River, Missouri. 
Szconp Szares, Vol. XIX, No. 55.—Jan,, 1855. 11 
