MEMOIES 



01' THE 



CAKNEGIE MUSEUM. 



VOL. V. NO. l. 



THE FRESHWATER FISHES OF BRITISH GUIANA, INCLUDING A 



STUDY OF THE ECOLOGICAL GROUPING OF SPECIES, 



AND THE RELATION OF THE FAUNA OF THE 



PLATEAU TO THAT OF THE LOWLANDS. 



By C. H. Eigenmann, Ph.D. 



INTRODUCTORY. 



I had two purposes in view in the trip to Guiana: first, to observe, photograph, 

 and incidentally collect as many species as possible for my monograph of the 

 characins; second, in connection with my general faunal study of the fishes of 

 South America to determine, if possible, the relation of the fish-fauna of the Guiana 

 plateau to that of the lowlands, more particularly the relationship existing between 

 the faunas of the upper and the lower Potaro. The two reaches of the PotarO are 

 separated from each other by the Kaieteur Fall, over which the water leaves the 

 Guiana Plateau by a drop of seven hundred and forty-one feet. Although all 

 other things were sacrificed to the two purposes mentioned, I cannot claim that 

 I accomplished them to my entire satisfaction. The conditions were all so novel, 

 the difficulties of travel so great, the heat so intense, the fauna so rich, the 

 time and the money at my command so limited, that I now occasionally regret 

 that at this or that point I did not use different means, or devote more time to 

 the objects in view. But to offset this regret I have many solid satisfactions. 



If seeing and recording a lot of "specimens," which have been disintegrating 

 for longer or shorter periods in alcohol, can be called acquaintance, I have been 

 acquainted with South American fresh-water fishes for many years. In contrast 



