MUSCIDiE: THE BLOOD-SUCKING MUSCIDtE 175 



which are not always low-lying, the species having been taken, 

 according to Austen, at an elevation of 5000 to 5500 feet. It 

 has the abdomen banded almost as conspicuously as G. tachi- 

 noides, from which it is distinguished, inter alia, by its larger 

 size and by having only the 2 terminal segments of the hind 

 tarsi dark : from the two following species it is distinguished, 

 inter alia, by the points emphasised in Austen's table. 



G. morsitans is the living document of the famous discovery 

 of Bruce and his colleagues, which proved this species — long 

 suspected to be the " cause " of nagana, or tsetse-fly disease 

 of domestic animals — to be a necessary medium for the 

 maintenance of the species of trypanosome that is the true 

 cause of that disease. G. morsitans has lately been brought 

 under suspicion as a possible agent in the transmission of 

 indigenous sleeping-sickness in an area (Nyassaland and 

 North-east Rhodesia) where G. palpalis is believed to be 

 non-existent. In this connexion it must be remembered that 

 it has been demonstrated experimentally on the one hand 

 that there are several species of trypanosomes that can be 

 " nursed " by more than one species of blood-sucking insect, 

 and on the other hand that there are several species of blood- 

 sucking insects that can " nurse " more than one species of 

 trypanosome. 



Glossina submorsitans, Newstead. 



Is said to differ from G. morsitans (i) in certain slight 

 differences in the form of the claspers of the male ; and (2) in 

 having the dark abdominal cross-bands much more sharply 

 defined, equally and more narrowly interrupted in the middle 

 line on segments 3 to 5, and only slightly rounded, but 

 abruptly sloping towards the lateral margins of the segments. 

 Mr Austen regards it as a race of G. morsitans. 



Glossina longipalpis, Wiedemann. 



This, according to Austen, is essentially a West African 

 species, but has also been found in the south-eastern corner 

 of the Congo Free State. It is slightly larger than G. 

 morsitans, has the dark abdominal cross-bands distinctly 

 wider fore-and-aft, and has a conspicuous fringe of fine hair 

 on the front margin of the 3rd segment of the antennae. 



