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Indiana University Studies 



C. ON VERTICAL DISTRIBUTION, PARTICULARLY IN THE 



PATIA RIVER 



No very precise limits can be set for the vertical distribution 

 of any of the fishes. Within limits otherwise suitable environ- 

 ment seems to affect distribution as much as altitude. Pygidiuin 

 belongs to the heights but may descend to the sea ; Astroblepus 

 belongs to the heights but may also descend to near the sea. 



In the south, Orestias and Pygidium reign on the greatest 

 heights, both are found in Lake Titicaca (12,000), and in Lake 

 Langilaio (about 14,000 feet). Lower down in the L T rubamba 

 river, into which Langilaio drains, come Ancistrus and a genus 

 allied to Bryconamericus. Elsewhere in Peru, Orestias attains 

 over 15,000 feet. In Ecuador, Astroblepus attains the greatest 

 height, 13,400 feet. Bryconamericus and Pygidium come next. 

 Astroblepus and Pygidium attain their maximum size in the 

 mountains of central and southern Peru. 



On the plains of Bogota, at about 9,000 feet, Grundulus, Pygi- 

 dium, and Eremophihis are found. Pygidium also occurs above 

 Bogota. At lbagUg- (4,250 feet) I secured a Rivulus, a Brycon- 

 americus, and saw a Geophagus ; an Astroblepus was reported. 

 At Boquilla. 5,700 feet, Astroblepus, Pygidium, Bryconamericus, 

 Hemibrycon, and Astyanax were found. 



The following table illustrates the vertical distribution in the 

 Patia basin. At 5,000 feet and upwards only Astroblepus, 

 Pygidium, and Bryconamericus occur. At 1,500 feet two out 

 of seven species are peculiar modifications of lowland forms. The 

 rest are lowland species. The fishes at this altitude are largely 

 fishes abundant in the lowlands, but not nearly all the lowland 

 fishes attain this height. While there are species which are 

 predominantly highland forms these may, in favorable places, 

 descend to near the sea. The reverse is also true tho perhaps 

 not to the same extent. 



