HOW THE TROUT CAME TO CALIFORNIA. 



spread itself widely in the streams of the green 

 and moist region west of the Cascade Range and 

 through the arid lava-strewn wildernesses which lie 

 to the east. Each stream received its quota of 

 trout ; but as the way was open up and down the 

 stream, the species remained essentially as it was 

 in Alaska. Isolation or separation from the main 

 body in some way is a prime factor in the perma- 

 nence of new forms. In Waha Lake 1 in Wash- 

 ington, a glacial lake which has now no outlet, the 

 trout became entirely cut off from the parent stock, 

 and a local race with shorter head and the black 

 spots gathered on the tail was formed by the 

 separation. In the central portion of this region, 

 east of the Cascade Range, we find still the an- 

 cestral forms of the nascent species which have 

 sprung from Salmo mykiss. In this region the 

 scales are small, but the cut-throat mark is often 

 wanting, and there are still living forms that seem 

 to mark a perfect transition 2 from Salmo mykiss 

 to Salmo gairdneri. In the region where these 

 forms are found, the true mykiss is nearly or quite 

 wanting. 



The trout thus came to the fountain-head of 

 the Columbia, and its great tributaries the Snake, 

 the Salmon, and Clark's Fork. In this Upper 

 Snake River it has become separated, since the 

 last lava flows, 'from the parent form, and it is 



1 The Waha Lake Trout has received the name of Salmo 

 mykiss bouvieri. This name was given by Major Charles Bendire, 

 its discoverer, one good soldier naming it for another. 



2 These transitional forms, abundant about Walla Walla and 

 in the Des Chutes River, are known as Salmo mykiss gibbsii, named 

 for the discoverer, George Gibbs, once governor of Washington. 



