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Indiana University Studies 



Cali in tributaries of the Cauca, at Boquilla, Piedra Moler, Car- 

 tago, Paila, Cali, and in the Cauca itself at the port of Call. 



From the torrential mountain tributaries, collections were 

 made at St. Agustin for the British Museum; in a line from 

 Honda to Bogota, on the Plains of Bogota, in a line from Bogota 

 thru Santander 1 , all during and for my Reconnaissance of Colom- 

 bia; in the Santa Marta Mountains by the party of the University 

 of Michigan; at Ibague and Toche, by myself; at Popayan by 

 Humboldt; and in Antioquia by parties of the American Museum 

 of Natural History. 



Our knowledge of the fauna is still deficient for all of these 

 regions, more particularly the upper Magdalena, the rapids of 

 the Cauca, the torrential streams of the Western and Central 

 Cordilleras. Nothing is known concerning the fauna of the Cesar. 



In a system as large as the Magdalena there are many units 

 of environment each of which has its own complement of species. 

 Not all of them unique, to be sure, but nevertheless containing a 

 per cent of uniques. The sum of the faunas of many such units 

 is very probably greater than the number of species found in a 

 smaller river system. The number of species in a given stream is 

 proportional to the size of the system to which it belongs. 



The Magdalena fauna is more like that of the Orinoco than 

 the Guayas fauna of Ecuador is like that of the Magdalena. The 

 resemblance is five times greater if the number of identical species 

 is taken as a criterion. 



There are one hundred and fifty-odd species belonging to 

 seventy-odd genera of fresh-water and brackish-water fishes 

 known to occur in the Magdalena basin. 



Of these the common eel and the tarpon were contributed by 

 North America thru the Caribbean Sea. The tarpon found in the 

 Caribbean Sea and Gulf of Mexico enters many of the rivers 

 discharging into them. 



The common eel of North America descends the ocean to 

 spawn. The young enter the rivers. So far but one small 

 specimen collected by the Expedition from the University of 

 Michigan has been found in the Magdalena or as far as that goes 

 from any of the rivers of South America. It was a stray. 



Gambusia, Mollienisia, Agonostomus, and four genera of the 

 Eleotridinse, possibly also Rivulus, were contributed by Central 

 America. 



^he fishes in this area were considered in " The Fish Fauna of the Cordillera of 

 Bogota." Journ. Washington Acad. Sci., X. pp. 460-468, 1920. 



