﻿ElGENMANN : FlSHES OF WESTERN COLOMBIA 



13 



B. THE ORIGIN OF THE FISH FAUNA OF THE DAGUA AND 



THE PATIA 



The Kio Dagua empties into the Pacific immediately south of 

 the mouth of the San Juan, at Buenaventura. The Dagua rises 

 near Cali, on the Pacific slope of the western Cordilleras, flows 

 northward between two chains of the western Cordilleras to 

 Caldas. North of Caldas it passes thru a desert rain shadow 

 cast by a western chain of the western Cordilleras, then breaks 

 thru the western chain in a narrow gorge flowing westward in its 

 lower course to the Pacific. The height of land between its 

 upper reaches and the Cauca basin is little over 6,000 feet at its 

 lowest place. Collections were made at Caldas, 3,722 feet, 

 Cisnero at the western end of the gorge, 1,046 feet, Cordova, 120 

 feet, and at Buenaventura (sea-level). The distance between 

 Caldas and Buenaventura is 49 miles; Cisnero and Buenaven- 

 tura, 33 miles ; Cordova and Buenaventura, 12 miles. Emptying 

 so near the mouth of the San Juan, it may be fair to assume 

 that all species common to the San Juan and the Patia occur 

 also in the Dagua. A number of rivers between the Dagua and 

 the Patia rise on the slopes of the western Cordilleras and flow 

 into the Pacific. 



The Patia is distinguished by rising with the Cauca in the 

 elevated plain of Popayan, between the eastern and western 

 Andes. The divide that separates the Cauca flowing north and 

 the Patia flowing south is imperceptible. The Patia has cut a 

 deep gorge in the western Cordilleras. Its lower, western course 

 flows in the wet territory. It seems quite probable that the 

 Patia cutting back from the coast has tapped upper tributaries 

 of the Cauca. If so, it happened late in the life of the stream, 

 for, aside from high mountain species, it captured no fishes from 

 the fauna of the Cauca. The highest mountain species in the 

 Cauca and the Patia lend color to the interchange of fishes be- 

 tween these rivers. 



Collections were made by Mr. Arthur Henn in the Patia basin 

 in the highland near Tuquerres and Sandona, at the mouth 

 of the Guaitara at about 1,500 feet, between the mouths of the 

 Telembi and the Magui, and by Messrs. Henn and Charles Wilson 

 in the Telembi, a large southern tributary of the Patia. 



The fishes of the Patia and the Dagua may have been derived 

 from the San Juan on the north, the Guayas basin on the south, 

 or from the Cauca, east of the western Cordilleras. 



