120 Barriers to Dispersion of River Fishes 
The mountain mass of Mount Shasta is, as already stated, 
a considerable barrier to the range of fishes, though a number 
of species find their way around it through the sea. The lower 
and irregular ridges of the Coast Range are of small importance 
in this regard, as the streams of their east slope reach the sea 
on the west through San Francisco Bay. Yet the San Joaquin 
contains a few species not yet recorded from the smaller rivers 
of southwestern California. 
The main chain of the Alleghanies forms a barrier of im- 
portance separating the rich fish fauna of the Tennessee and 
Ohio basins from the scantier faunz of the Atlantic streams. 
Yet this barrier is crossed by many more species than is the 
case with either the Rocky Mountains or the Sierra Nevada. It 
is lower, narrower, and much more broken,—as in New York, 
in Pennsylvania, and in Georgia there are several streams which 
pass through it or around it. The much greater age of the 
Alleghany chain, as compared with the Rocky Mountains, seems 
not to be an element of any importance in this connection. Of 
the fish which cross this chain, the most prominent is the brook 
trout,* which is found in all suitable waters from Hudson’s 
Bay to the head of the Chattahoochee. 
Upland Fishes.—A few other species are locally found in 
the head waters of certain streams on opposite sides of the range. 
An example of this is the little red “fallfish,”+ found only in the 
mountain tributaries of the Savannah and the Tennessee. We 
may suppose the same agencies to have assisted these species 
that we have imagined in the case of the Rocky Mountain trout, 
and such agencies were doubtless more operative in the times 
immediately following the glacial epoch than they are now. 
Prof. Cope calls attention also to the numerous caverns existing 
in these mountains as a sufficient medium for the transfer of 
many species. I doubt whether the main chains of the Blue 
Ridge or the Great Smoky can be crossed in that way, though 
such channels are not rare in the subcarboniferous limestones 
of the Cumberland range. In the brooks at the head waters of 
the Roanoke River about Alleghany Springs in Virginia, fishes 
of the Tennessee Basin are found, instead of those characteristic 
* Salvelinus fontinalis. 
+ Notropis rubricroceus Cope. 
