MAMMALS OF ANGLO-EGYPTIAN SUDAN — SETZER 449 



mammals of the Sudan are not limited in their distribution by the Nile. 

 This is particularly so in the White Nile drainage where vast areas of 

 sudd occur. The formation of sudd dams across channels allows for 

 free interchange of mammal populations from bank to bank in certain 

 areas in the south. The extent to which the Nile serves as a barrier in 

 its more northern reaches is not clearly demonstrable since collections 

 from either bank are not known north of Khartoum. From the scanty 

 evidence available, it does seem that the Nile serves as a barrier to 

 certain kinds of mammals in the more northern reaches but to a less 

 appreciable degree in the south. 



Africa has been divided into major biotic districts based on the 

 distribution of plants and birds by Chapin (1932). Some of these 

 districts, in the Sudan, do not seem to correspond to mammal distri- 

 bution at any taxonomic level. The mammals of the Sudanese Arid 

 District and the Sudanese Savanna District appear to be alike. Only 

 the genus Galago seems to have a distribution that fits the general 

 outlines of the Sudanese Savanna District, but this genus occurs also 

 in areas that are referred to the Abyssinian Highland District. The 

 geographic area assigned to the Ubangi-Uelle Savanna District appears 

 to be too large, since no elements of this district have been found east 

 of the Nile. The Abyssinian Higliland District does not appear to be 

 represented in the Sudan to any degree. The only element which 

 possibly could be assigned to this district is Praomys albipes, whose 

 main range is in the highland area of Ethiopia. The Somali Arid 

 District was thought by Chapin to include the northeastern portion 

 of the Sudan (bounded by Eritrea and the Red Sea) and the portion 

 in the extreme southeast. The former area is probably correctly 

 included in the Somali Arid District since the maned rat Lophiomys 

 and the small dik-dik Rhynchofragus are found there. No mammals 

 characteristic of the Somali Arid District have been found in the 

 southeastern area, which may be included more properly in the East 

 African Highland District. Otherwse, the bounds assigned by 

 Chapin to the East African Highland District in the Sudan are satis- 

 factor}' from the point of view of mammalian distribution, since the 

 affinities of most of the mammals of this area are with those of Kenya 

 Colony and East Africa. 



In certain areas mammals do not conform as well to the biotic dis- 

 tricts of Chapin as do birds. The mammalian fauna of the Sudan is 

 rather homogeneous and the major portion of the country may be 

 assigned to what I would call the Sudanese Ai'id Savanna District. 

 The remaining parts of the sudan have mammalian faunas which 

 show some affinity to faunas of the Somali Arid District, the Ubangi- 

 Uelle Savanna District, and the East African Highland District. 

 The area l3^ing along the Ethiopian border is somewhat distinct bo- 



