RESEARCH IN BRITISH WEST AFRICA. 319 



eastern half of the Protectorate. It is also an important political centre, 

 and all officers stationed on the Chad and Benue systems must pass through 

 Lokoja going to and from their stations. Here also is situated one of the three 

 large European hospitals of the Protectorate, under the charge of a Senior 

 Medical Officer. Further, it is the headquarters of the 2nd Battalion of the 

 West African Frontier Force. All these combined together ensure a large 

 permanent European population as well as a continual ingress and egress of 

 officials and others passing north and south. 



The town stands on the right bank of the Niger, at the base of a large 

 Hat-topped hill, Mount Patti, which is covered with moderately thick bush. On 

 the left bank is a large, flat, alluvial plain formed by the confluence of the two 

 rivers. Close to the river are several trading factories, the Marine Head- 

 ijuarters, and the stores of the Public Works Department, and, owing to the 

 nature of the bank and the varying level of the river, pools of stagnant water 

 are far from infrequent, in many of which mosquito larvae were found. 

 Mosquitos are very troublesome all over this pai-t, and swarms of them come 

 from the banks and invade the steamers lying alongside. In four buildings 

 occupied by Europeans, as well as on a launch tied up to the bank, I found 

 Stegomyia fasciatu and Myzonvyia costalis. The majority of the European 

 houses are on much higher grovmd, and at some distance from the river ; but in 

 the Post Office, some five hundred yards from the river bank, S. fasciata was 

 seen. Throughout the town, the most prevalent mosquito was M. costalis. 



Glussina palpalis has been recorded from Lokoja, but although I visited this 

 town on two different occasions, first in August, during the rains, and afterwards 

 in January, in the dry season, I saw none, and from the nature of the clearings 

 so efficiently carried out by the political and medical officers, I do not think that 

 this species actually breeds within the limits of the settlement, but it may 

 occasionally follow natives or others from the bush on Mount Patti. During my 

 second visit. Dr. E. A. Chartres, the Senior Medical Officer, was clearing a 

 small banana grove which existed in a low-lying, damp situation, but careful 

 search failed to reveal either the insects or pupal cases. In June, 1911, 

 Dr. Chartres caught a specimen of G. tachinoides near his house, and in 

 August of the same year one G. palpalis inside a ward of the European Hospital. 



Ticks are said to be very troublesome at certain seasons of the year : both 

 Amhlyomma variecjatuni and Rhipicephalus sanyuineus have been recorded from 

 the district. CuUcoides sp., and Simulium sp. are abundant. Myzomyia costalis, 

 as has been mentioned, is the most prevalent mosquito, but apart from this 

 species and Stegomyia fasciata near the river, the only others seen during my 

 visit were Mansonioides uniformis, Mucidus mucidus and Nyssorliytichus pharo- 

 ensis. Dr. Chartres has, however, collected the following species since that 

 time : — -Culex decens, C. grahami, C. guiarti, C. invidiosus and Myzomyia umbrosa. 

 Hippacentrum versicolor has been recorded from Lokoja, but is far from common, 

 while in and near the stables Stomoxys nigra, S. calcitraits and Hippohosca 

 macidata simply swarm in hundreds. 



The number of horses in Lokoja is necessarily large, and the rate of mortality 

 is excessively high. Capt. Mauuk, late I. M.S., who has made a special study of 



