558 ^Ir. G. A. Boulenger on 



The additions to the fisli-fauna of Lake Rudolf wliich this 

 collection affords [Gymnarchus niloticus^ lleterotis niloticiis) 

 only further emphasize the almost purely Nilotic character 

 of this fauna, as remarkable a fact as is, on the other hand, 

 the very insignificant proportion of Nile elements in the fish- 

 fauna of Lake Victoria. Lakes Abaya-Margherita also 

 possess some fishes particularly suggestive of the Nile, but 

 here they are associated with a preponderating number of 

 forms characteristic of the eastern parts of Africa. 



It is worthy of note that nearly all the species of fishes 

 which by their association impress a so strikingly Nilotic 

 character on the fauna of Lake Rudolf belong to the set 

 which extends westwards to Lake Chad and the Senegal and 

 Niger. 



I. — System of the Bltje Xile. 



1. GuDAK RiVEK, a fast-running stream, about 25 )-arcls wide, 



flowing from the Rogghe Mountains northwards to the Blue 

 Nile. Altitude 3400 feet. 

 Barhus plagiosiomns, B. gudaricus. 



2. Metxi River, a fast-running stream, about 20 j-ards wide, 



flowing from Tuludimtu northwards to the Gudar River. 

 AUitude 3500 feet. 

 Discognutlius dembeensis, Varicorhinus heso, Barhus gudaricus. 



3. DiDEssA River, about GO yards wide, flowing from (iuma north- 



wards to the Blue Nile. Altitude 3500 feet. 

 Laheo ForsJcalii, Discognathus dembeensis, Varicorhinus beso, 

 Barbus surJcis, B. intennedius, B. ZajjJiiri, B. ajffinis, B. nedgia. 



4. Jujtr RivEK, about 10 yards wide, flowing from the hills of Guma 



to the Didessa River. Altitude 2000 feet. 

 Labeo Forskalii, Discognathus dembeensis, Varicorhinus beso, 

 Barbus intennedius, B, leptosoma, B. eumgstus. 



5. Uegessa River, about 15 yards wide, flowing north-west to the 



Wama River, a tributary of the Didessa River. Altitude 

 2300 feet. 

 Varicorhinus beso, Barbus intermedius. 



II. — System of the Omo. 



1. Omo River at Kullo, width 150-200 yards. Altitude 2000 feet. 

 Labeo cyUndricus, Barbus Bottegi. 



2. CojEB River, about 50 to GO yards wide (in tlic rainy season), 



flowing from Guma and the Cialla hills to the Omo. Altitude 

 2500 feet. 

 Alestcfi macrolepidotus, lleterobranchtis longijlh's. 



