276 SCIENCE SKETCHES. 
and went away contented with that. A much 
better angler, Mr. Charles J. Fisher of Leadville, 
was not satisfied with our conclusions, and insisted 
that we should go back with him. We did so, and 
were rewarded by many specimens of the beautiful 
“ Vellow-fin Trout,”’?! first introduced to science 
in 1889. This is a large trout with bright yellow 
fins, a yellow stripe along the sides, pale flesh, 
and the black spots very small and all gathered on 
the tail. It has not yet been found in any other 
waters. It is very different in structure and aspect 
from the Greenback Trout which swarms with it 
in the Twin Lakes. It must be descended from 
the Colorado Trout, which inhabits the other side 
of the Divide. How it crossed the Saguache 
Mountains from the Gunnison or from the Roaring 
Fork, no one can now say, but that this crossing. 
was a fact I have no reason to doubt. 
At this point the “lay of the land” renders a 
diversion necessary. When you come overland to 
San Francisco by way of the Central Pacific, 
after you have passed Ogden an hour or so, you 
will notice a break in the mountains to the north- 
ward. Through this break to the Snake River the 
waters of the Great Salt Lake once flowed. It 
was not a salt lake then, and it was. much larger 
than now. The old lake has been called Lake 
Bonneville. You may trace its former boundaries 
as terraces upon the slopes of the hills. You can 
see them from the car windows, looking out in 
almost any direction. Through this break once 
1 The Vellow-fin Trout of Twin Lakes is Salmo mykiss mac- 
donaldi Jordan & Evermann. 
