280 SCIENCE SKETCHES. 
or Salmo gatrdneri. This gairdneri we regard as a 
species different from Salmo mykiss. Its mouth is 
smaller, and the sides more red. But the fading of 
the cut-throat mark is the chief sign by which we 
may know it from its ancestors; and this must 
have passed away by gentle stages, for in the Kern 
trout and the Sasta trout — its descendants, if this 
supposition is true —there are still traces of the red 
dash, which the common Steel-head no longer 
shows. 
Let us suppose that the descendants of the 
gibbsit entered the Lower Columbia when the 
blockade at the Cascades was worn through. 
They must have found the sea congenial, for with 
the gairdneri we find more of the migrating habit 
than in any of the wykess forms. Trout who go 
to the sea must some time come back to the 
mountains, for all trout and salmon cast their eggs 
in the gravel of fresh-water brooks or cold lakes. 
Migrating trout go up all the streams from Point 
Concepcion to Vancouver Island. Ocean feeding 
makes large trout. Ten pounds is not uncommon, 
and they have been known to run as high as thirty. 
These sea-run fishes are known as Steel-heads, or 
Salmon Trout, and are often taken for salmon. 
They are trout, nevertheless, not salmon at all. 
The name Steel-head, being used for no other fish, 
is well applied to them. 
They are a good and gamy fish in their season, 
but are not always so when taken in the rivers. 
The Steel-head spawns in the winter, later than the 
salmon, and when taken as spent fish in February 
or March, it is often coarse and poor. It then 
