THE SALMON FAMILY 47 
These fish during the early part of their lives are 
almost identical in appearance, and for the first year or 
two possess bars across the body known as parr marks. 
These parr marks probably persisted throughout life in 
the primitive trout; even now they are permanently 
present on the mature trout of the Scottish burn, where 
food is scarce. Their spawning habits also point to a 
common freshwater ancestry, for salmon, sea trout, and 
brown trout that have acquired the habit of going to 
sea return to fresh water to spawn. Neither will the 
eggs of these fish live in sea-water. 
As illustrations of the possibilities of variation in the 
brown trout, let us consider the Loch Leven at home, 
and the brown trout as he now appears in Tasmania and 
New Zealand. 
The Loch Leven trout, with its silvery sides and black 
cross marks, turned into a southern trout stream, in two 
or three months changes his colour and markings, and 
is difficult to distinguish from the common brown trout. 
Brown trout introduced into Tasmania and New 
Zealand at first maintained the characteristics of our 
trout at home. Now these fish weigh twenty to thirty 
pounds, migrate to sea and return to fresh water to 
spawn, and in appearance are as silvery as a salmon. 
The young, however, of this altered brown trout during 
the first year of life cannot be distinguished from yearling 
brown trout as seen at home. 
In view of the above facts, let us look at the life 
history of the brown trout as a type, and then consider 
