TSETSE-FLIES OF THE KABALOALBERTVILLE RAILWAY. 171 



of forest. Here and there the immediate vicinity of the railway seems very little 

 wooded, although in reality the route is surrounded by forest ; this is caused by the 

 artificial clearing of the route referred to above. 



The second section, to summarise, shows a vegetation which is transitory between 

 park and forest, or an alternation of these two types of vegetation. 



Third Section. 



This is the most picturesque and the most interesting part of all the journey. After 

 passing thevRiver Niemba close to its mouth, which is about 15 metres wide with open 

 banks, the railway follows the Lukuga until it joins Tanganyika. The distance 

 between the river and the railway is variable — generally 50 to 100 metres, sometimes 

 even more, but very often much less — and in many places the railway follows the 

 river bank at only a few metres distance. The streams (and consequently the bridges) 

 are very numerous in this part. It is this section (the valley of the Lukuga) which I 

 examined five years ago. With regard to vegetation, the valley of the Lukuga and 

 its sides are park-like. The river itself is bordered with papyrus, trees, shrubs and 

 creepers. According as one or other of these types of plants predominates, the river- 

 side vegetation becomes more or less thick, but the banks are almost always well 

 shaded, although they could hardly be described as wooded. It is especially in this 

 third section that artificial clearing is most noticeable. In several places, especially 

 in the proximity of the habitations of European engineers, there are no trees left 

 between the railway and the river, nor for a certain distance on the other side of the 

 railway. 



The Species of Tsetse-flies. 



In order to simplify the description, I shall deal separately with the Glossina of 

 each section, beginning with the third and finishing with the second. 



Third Section. 



During my first journey in this region, in 1911, 1 found G. palpalis and G. morsitans, 

 the first along the Lukuga and the second throughout the valley. In the vicinity of 

 the village Kibogolo, corresponding to km. 232 (but on the opposite side of the river), 

 I also found G. brevipalpis (which I, in common with others, identified at that time as 

 G. fusca). Since then, with a better understanding of the habits of G. brevipalpis, 

 I suspected that this species also would be found more or less throughout the valley, 

 and in fact I did find G. brevipalpis on the railway itself in three places which I visited 

 in the evening, especially at km. 259, 219, and near to the Niemba. I was surprised 

 at the rarity of G. morsitans. I saw none in the train and I found very few specimens 

 in the two places where I stopped, in spite of the fact that that species was present 

 there in great numbers in 1911. What has become of it ? Well, I think that the 

 partial diminution of G. morsitans is a consequence of the progressive clearing of the 

 railway. I am convinced that beyond Lukuga, on the right of the valley, where 

 conditions have not changed, G. morsitans is as numerous as ever. But conviction 

 is not sufficient for affirmation ; to make certain it must be proved on the spot that 

 facts correspond to supposition. I hope soon to be able to elucidate this question. 

 It is also probable that G. pallidipes exists in the valley. 

 (C394) d2 



