AUG 11 



PROCEEDINGS 



OF THE 



AMERICAN PHILOSOPHICAL SOCIETY 



HELD AT PHILADELPHIA 

 FOR PROMOTING USEFUL KNOWLEDGE 



THE ORIGIN AND DISTRIBUTION OF THE GENERA OF 



THE FISHES OF SOUTH AMERICA WEST OF THE 



MARACAIBO, ORINOCO, AMAZON, AND 



TITICACA BASINS.^ 



By carl H. EIGENMANN. 



(Read March 4, 19^1.) 



The territory defined in the title includes Panama, Colombia, 

 west of the Cordillera de Bogota, and the Pacific slope of Ecuador 

 and Peru. 



The area is bounded on the south by the desert of Atacama, on 

 the west by the Pacific Ocean, on the north by the Isthmus of 

 Panama and the Caribbean Sea, on the east by high mountains, the 

 Sierra Nevada de Santa Marta, the Cordillera de Perija, and the 

 Cordillera of Bogota in Colombia, in small part by the Cordillera 

 Oriental in Ecuador, and by the Cordillera Occidental in the rest 

 of Ecuador and the whole of Peru. 



The largest river basin in this area is that of the Magdalena. 

 The Magdalena, Sinu, Atrato, and Chagres drain into the Atlantic ; 

 the Chepo, Tuyra, San Juan, Dagua, Patia, Mira, Esmeraldas, 

 Guayas, and many short turbulent rivers south of it drain into the 

 Pacific. The coastal portion north of central Ecuador is very wet, 

 with a heavy annual rainfall ; the lower portion south of Guayaquil 

 is without rain. The rivers are supplied with water from the moun- 

 tains only. 



In a faunal volume recently finished, 388 species of fresh-water 

 fishes are recognized from this area. They are referred to 108 



^ Contribution from the Zoological Laboratory of Indiana University, 

 No. 180. 



PROC. AMER. PHIL. SOC, VOL. LX, A, JULY 25, I921 



