HOW THE TROUT CAME TO CALIFORNIA. 2/9 



greasewood, enlivened only by the rattle of the 

 Sidewinder. In the glacial period this region had a 

 different climate. Melting ice once filled the terri- 

 ble deserts of Amargosa and Panamint with sweet 

 waters. In some way or other this region may 

 have been traversed by the trout. I once thought 

 that from the Colorado to the Kern 1 the trout must 

 have come into California. It may be so ; but if our 

 theories follow the line of least resistance, there is 

 an easier way. If the trout came from the Colorado 

 to the Kern, it has in the transition lost most of the 

 red of its cut-throat mark, but not all of it. The 

 scales became somewhat larger, the red band on 

 the side more distinct, and the spots extended for- 

 wards. In all these regards we come nearer to the 

 trout of the Walla Walla region, the one we call 

 Salmo my kiss gibbsii; and while it is possible that 

 the Kern Trout {gilberti) came from the Colorado 

 trout (pleuriticus), which they greatly resemble, my 

 present impression is that they did not. 



Let us try this supposition. The old mykiss 

 stock filled the Columbia. After the lava flows 

 had formed Shoshone and American falls, the trout 

 of the Upper Columbia (lewisi) were shut off from 

 the others. Perhaps the waterfall of the Cascades 

 separated those of the Middle Columbia from those 

 of the lower portion of the river. In any event, the 

 gibbsii became somewhat different, losing in part 

 its cut-throat mark, and passing into the small- 

 scaled white-throated form we call the Steel-head, 



1 The Trout of Kern River is Salmo gairdneri gilbertt Jordan, 

 named for its discoverer, Dr. Charles H. Gilbert, who has been 

 for twenty years my colleague in the study of our fishes. 



