﻿Indiana University Studies 



No. 8 BLOOMINGTON, INDIANA September, ]912 



[Contributions from the Zoological Laboratory of Indiana University. No. 127.] 



Some Results from An Ichthyological Reconnaissance 

 of Colombia, South America 



Carl H Eigenmann 



Colombia occupies the northwestern corner of South America. 

 In extent of area it is about equal to that of the states, exclusive of 

 ]\Iaine, lying east of the iMississippi and north of Tennessee and 

 North Carolina. The southeastern part lies in the valleys of the 

 Amazon and the Orinoco. Western Colombia, the part with which 

 this paper is concerned, includes three large valleys extending 

 north and south, whose boundaries are formed by four chains of 

 the Cordilleras. Tii the eastern valley fiow^s the Magdalena River, 

 and in the central valley, the Cauca. These rivers unite and empty 

 into the Caribbean Sea. In the western valley are two rivers, the 

 Atrato, floAving northward into the Caribbean Sea, and the San 

 Juan, southward into the Pacific Ocean. The height of the land 

 between tiie Atrato and the San Juan is not much, if any, more 

 than 300 feet above sea-level. 



The eastern and central Cordilleras diverge from a common 

 chain in southern Colombia. The eastern chain extends to the 

 Caribbean Sea and forms an effective barrier between the faunas 

 of the Amazon, the Orinoco and the ]\[aracaibo basins on the east, 

 and of the ^Magdalena basin on the w^est. (A branch chain, de- 

 flecting from the eastern one, extends through Venezuela. With 

 this we are not concerned. Betw'een it and the eastern range lies 

 the basm of Lake ]\Iaracaibo.) 



The fauna of the Magdalena basin has long been separated from 

 that of the rest of South America and is bounded by this chain of 

 the Cordilleras. The central Cordilleras, which reach the snow- 

 level in several places, form a barrier between the fauna of the 

 Mag'dalena and that of the upper Cauca. But since this central 

 range does not extend as far northward as the eastern and western 

 chains, the faunas of the Cauca and of the ^lagdalena are enabled 

 to unite north of it. 



