﻿RESEARCH IN BRITISH WEST AFRICA. 189 



(c) G, fusca-group. 



Three species belonging to this group are represented in Southern Nigeria. 

 The only other species so far attributed to this group is G. fnscipleuris, of which 

 only the type specimen, from the Congo Free State, is known. 



Glossina fusca is most common in the hilly regions of Ilesha and Oban, but has 

 also been found on the Yewa River and at Bende, while a single specimen was 

 taken by the writer at Yaba, near Lagos. This species has been recorded only 

 once from Northern Nigeria, and that from the Kabba Province, which borders 

 on Southern Nigeria. 



Glossina nigrojusca has been found only on the Oni River, but, as in the case 

 of G. caliginea, its distribution probably extends along the lagoon-delta area. 



Glossina tabaniformis has been recorded from only two localities in Southern 

 Nigeria, namely, Ikom and Oban, both in the Cross River basin and at the foot 

 of the Kameruns. 



(d) G-. brevipalpis-group. 



The only species belonging to this group which occurs on the West Coast is 

 G. medicorum ; it has been recorded only once from Southern Nigeria, namely, 

 from Asaba. The other two species, G. brevipalpis and G. longipennis, are 

 peculiarly East African forms. 



These few notes refer particularly to the distribution of the various species in 

 Southern Nigeria, but I should like here to add some remarks on the general 

 distribution of some of these species in Nigeria as a whole. For this purpose the 

 general physical configuration, the nature of the vegetation, and the character of 

 the climate and rainfall must be taken into account. The main characteristics of 

 each of these have been given in some detail in this and a previous report, so that 

 it is necessary here only to refer to the more prominent features. 



Nowhere in this area are there any very prominent mountains, and, as those 

 ranges which exist are important only in so far as they constitute the various 

 watersheds, they may be considered in a very general way. The most important 

 of these is the Bauchi Plateau, which separates the Niger-Benue river system in 

 Northern Nigeria from the Lake Chad system. Next, there is a spur of the 

 Kameruns, which abuts the boundary of Northern and Southern Nigeria and 

 separates the Benue system from that of the Cross River. In the north-west of 

 Southern Nigeria, there is a small range of hills which divides the Niger from 

 the series of small rivers in the Western Province of Southern Nigeria, while this 

 same range, continuing southwards and eastwards, forms the western limit of the 

 Niger system. 



Thus it will be seen that there are four separate river systems. By far the 

 largest and most important is the Niger-Benue system, which drains nearly half 

 of Southern Nigeria and almost three quarters of Northern. In Southern Nigeria 

 there is also the Cross River system in the Eastern Province and a series of 

 small rivers in the Western, while in the north-east corner of Northern Nigeria 

 there is the system of rivers which drain into Lake Chad. It has been noted 

 elsewhere in this report that along the coast region of Southern Nigeria all the 

 rivers in that colony are united by a series of creeks and lagoons. Consequently, 



