126 =, Ayres on the identity of 
This completes my description. And now in what does 
our fish differ from the European. The general shape of the 
body, all its proportions, the jaws, the peculiar structure of 
the nostrils, the situation of the eyes, the branchial membrane 
and rays, the teeth in their various positions (except the max- 
illaries) the lateral line, the surface of the body, the colors, 
the position and colors of the fins, all agree in the most com- 
plete and perfect manner. The only points in which there is 
the slightest want of coincidence are, the spines on the side of 
the head, the teeth on the maxillaries, and the tubercles on 
the branchial arches. 
In regard to the preopercular and opercular spines, it may 
be remarked that this is one of the items in which Artedi and 
Bloch do not agree in their description of the European fish. 
Of course one of them must be wrong, and from the nature of 
the case it seems probable that Artedi is the one who is if 
error. In our American fish the opercular spine is very small 
and will not be detected without close observation, and in the 
gobio it may very easily have escaped the notice of Artedi. 
Bloch mentions two spines, but his description and figure 
contradict each other. The figure agrees with our specimens 
but the description does not. The want of correspondence, 
therefore, between our fish and this part of Artedi's descrip- 
tion seems a matter of very little value, and one on which no 
argument can be founded for the separation of the species. 
In regard to the teeth we have another point of discrepancy. 
Artedi says they are “on each side on the limbs of the max- 
illaries." There is here also, apparently, an error in Artedi's | 
account, because it contradicts the common, and almost uni- 
versal, arrangement of the teeth in fish. "The teeth of the 
upper jaw are in general situated on the intermazillaries. In- 
deed I know of no fish in which there are teeth on the max- 
illaries, with none on the intermaxillaries, as Artedi has stated 
in regard to the gobio. 
© I have written thus far in reference to these items of difer 
ence, in order to show that they present no argument against - 
