THE NATURE AND ORIGIN OF THE FISHES OF THE 

 PACIFIC SLOPE OF ECUADOR, PERU AND CHILI.^ 



(Plates VIII-X) 



By carl H. EIGENMANN. 



(Read April 22, 1921.) 



There are three distinct faunas on the Pacific slope of South 

 America and west of the Cordillera of Bogota. 



One of these, the richest, occurs in Panama, southeast of the 

 Canal Zone, and in Colombia, west of the Cordillera of Bogota. 



The second of these faunas occurs in the Guayas basin of 

 Ecuador, and trails southward at least to the Rio Rimac at Lima. 



The third occupies the Pacific slope of Chili trailing northward 

 to the Rio Rimac or possibly the Rio Santa. 



The first two are part of the tropical American fauna. The 

 third belongs to the south temperate fauna. 



In a series of articles I have dealt with the nature and origin 

 of the freshwater fishes of Panama,- of the Pacific slope of the 

 Cordillera Occidental of Colombia,^ of the Magdalena river basin, ^ 

 of the Cordillera of Bogota,^ and of- the general horizontal distribu- 

 tion of all of the fishes west of the basins of Lake Maracaibo and 

 Titicaca, and west of the Orinoco and Amazon river basins.^ 



1 Contribution from the Zoological Laboratory of Indiana University, 

 No. 181. 



2 ■' The Freshwater Fishes of Panama East of 80° West," Indiana Uni- 

 versity Studies, No. 47, pp. 3-19, 1921. 



3 " The Fishes of the Rivers Draining the Western Slope of the Cordillera 

 Occidental of Colombia," 1. c. No. 46, pp. 1-20, 1921. 



* " The Magdalena Basin and the Horizontal and Vertical Distribution of 

 its Fishes," 1. c, No. 47, pp. 21-34, 1921. 



5 " The Fish Fauna of the Cordillera of Bogota," Journ. Wash. Acad. Sci., 

 X., pp. 460-468, 1920. 



® " South America West of the Maracaibo, Orinoco, Amazon, and Titicaca 

 Basins, and the Horizontal Distribution of its Freshwater Fishes." Indiana 

 University Studies, No. 45, pp. 1-24, 1920. 



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