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EIGENMANN— ORIGIN OF FISHES OF THE 



later underwent an independent evolution. South of the Guayas 

 the genera of the Guayas disappear one after another. The Peru- 

 vian rivers draining into the Pacific have lost all but that portion of 

 the original fauna which can withstand their present torrential 

 course and the great seasonal fluctuation of their waters. 



In central Peru, the Guayas fauna and the Chilian fauna touch. 

 In the Rio Rimac at Lima, Bryconamericus pcruaniis and Lebiasina 

 biuiaculafa are remnants of the ancient fauna, while Basilichfhys 

 scniotilus is the beginning of the Chilian fauna. 



The reputed resemblance of the Guayas fauna to that of Central 

 America has been based on mistaken identifications. Only Hoplias 

 microlepis points to any resemblance not bridged in the distribu- 

 tion. 



Several of the prominent genera of the Guayas are also found 

 in the Atrato-Magdalena, but not in the region between them. 

 They have been independently acquired by the Magdalena and by 

 the Guayas. 



The Fresh-water Fishes of Chili. 



The fishes of Chili and east of the Andes, south of a line extend- 

 ing from Buenos Aires to Alendoza, dififer from those of tropical 

 America to the north of this line. The fishes of this, the Patagonian 

 Region, were described in " The Fresh-water Fishes of Patagonia 

 and an Examination of the Archiplata-Archhelenis Theory " 

 (Reports Princeton University Expedition to Patagonia, III., 



