1889] Anomalies in Distribution 



similar connecting river basins have long been re- 

 corded. In Venezuela the Rio Cassiquiare connects 

 the Orinoco near its head with the Rio Negro, a large 

 tributary of the Amazon. In like fashion in western 

 Brazil a cross-stream joins the Rio Tapajos of the 

 Amazon drainage with the Paraguay of the La Plata 

 basin. Across these marshy uplands a fish readily 

 makes its way. It is also reported that during the 

 war they were utilized for a hostile purpose, a 

 matter to which I may revert in later pages. 



According to popular idea each animal species 

 has been somehow placed in the surroundings best 

 suited to its development. On this theory failure 

 to fill with trout the crystal streams of Yellowstone 

 Park must be regarded as a strange oversight on the 

 part of Mother Nature. The real fact is that each 

 species enters and occupies every attainable favor- 

 able environment, though access to the best is often 

 debarred. Pursuant to our report, the Eastern Bringing 

 Brook Trout Salvelinus fontinalis the Euro- in new 

 pean Brown Trout Salmo fario and the Shasta 

 Rainbow of California Salmo shasta were soon 

 introduced into all the important Yellowstone Park 

 waters. 



Another interesting problem in fish dispersion Problem 

 with which Evermann and I have had to deal con- *% 

 cerns the three species of Golden Trout developed Trout 

 in the Kern Basin of the High Sierra. Each of these 

 three is a result of the long-continued isolation of a 

 group of individuals shut away from the mass of 

 their fellows. In the upper reaches of the Kern, 

 three of its tributaries South Fork, Soda Creek, 

 and Volcano Creek were suddenly blocked thou- 

 sands of years ago by a long, continuous dyke of 



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