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L. Agassiz on the Ichthyological Fauna of Western America. 91 
name of Catostomus macuiosus, suspecting however, what is 
true, that this may be only a variety of the former. Soon after- 
wards Rafinesque described the same species from the Ohio and 
its tributaries, under four different names, as Catostomus fascio- 
laris, C. flexuosus, C. megastomus, and C. xanthopus. Again, 
his Exoglossam macropterum, for which he afterwards proposed 
the generic name Hypentelium is only the young of the same 
species ; finally Valenciennes, though copying the description of 
Cat. nigricans and C. maculosus from Lesnenr’s paper, describes 
anew original specimens of the former species, which Lesueur 
had sent to the Jardin des Plantes under a new name, as Cat. 
planiceps. We have thus eight specific names for a single spe- 
cies, the only one thus far known of this genus. In order to sub- 
Stantiate this assertion. | ought to state that though there are no 
marked differences between males and females in this genus, 
which may lead to the establishment of nominal species, as in 
the genus Moxostoma, the young and adult differ greatly in their 
coloration, being first strongly banded ‘transversely, then more 
mottled, and afterwards the bands and blotches of dark color fa- 
ding into isolated specks and finally disappearing entirely, the lower 
fins, and the abdomen becoming in the same proportion more 
brightly tinged, especially in the spawning season, as the upper parts 
of the body grow lighter. ‘hese four stages have misled Rafin- 
esque to distinguish four species; his OU. fasciolaris, about eight 
inches long, with small transversal black lines, is described from a 
Juvenile specimen, his C. flexuosus from ten to ticelve inches long, 
more plain, is described from nearly full grown specimens; his 
C. megastomus, yellowish beneath, appearing in shoals in March. is 
drawn from a male in the spawning season ; his C. xanthopus, with 
lower fins yellowish is a younger male; his Exoglossum macrop- 
terun is drawn from a very young specimen with fully protruded 
mouth, Thus we account for all the nominal species of Rafin- 
esque. That he should have taken no notice of Lesueur’s de- 
scriptions, is the natural consequence of the assumption upon 
which Rafinesque works throughout, that the fishes of our west- 
= waters differ uniformly as species from those of the Atlantic: 
reams. The mistake of Valenciennes arose from another 
Source. It was the habit of Lesueur to send to the Jardin des 
Plantes, original specimens of all his species, carefully labelled, 
Whether he had published descriptions of them or not, and we 
ud in the great Histoire Naturelle des Poissous, many species de- 
seribed by Cuvier and Valenciennes, uuder Lesnenr’s name, even 
though the latter had never himself published any notice of 
them.* Of Catostomus nigricans, Lesueur sent two dried speci- 
* How honor : with e some Naturalists are run- 
tng. for the questionable eraetn of being the Ast to name species, uibg even 
"Sorts of unw hy tricks to secure them. 
