39 8 
coarse teeth and a series of file-like plates. These are 
capable of being completely everted and consequently, 
when the proboscis is rotated as a whole, would tear 
their way through the skin. The proboscis proper 
consists of three parts (i) the dorsal labrum, (2) the 
ventral labium, which partly embraces the labrum 
with a series of inter-locking teeth, and (3) the hypo- 
pharynx, which lies in a groove in the labium. The 
hypopharynx has two small lateral appendages, and the 
tips of the labrum are in apposition with these and 
keep it in its groove. Owing to the fusion of the 
labrum in the bulb of the proboscis, no independent 
longitudinal movements of these parts is possible. 
(Fig. 1 26a). 
Classification of Species of Glossina 
(A) Hind tarsi entirely dark. 
(a) Abdominal segments with sharply defined pale 
hind borders. Second segment has a conspicuous 
square or oblong pale area in the centre. 
1. Gl. tachinoides ( = Gl. decorsei). —The smallest 
tsetse fly, 8 mm. excluding proboscis. $ smaller. In 
the ? the tarsi are basally somewhat pale. 
(<m) Abdominal segments with hind borders, if 
lighter, extremely narrow. Second segment has pale 
area triangular. Larger species than (a). 
2. Gl. palpalis. —Darkest of all species of Glossina. 
Third joint of antenna dusky-brown to cinereous black. 
2A. Gl. palpalis , v. wellmani (= Gl. bocagei). —Dis¬ 
tinguished from the type by its having the frontal stripe 
pale ochraceous ; thoracic markings much reduced, so 
that the thorax in a well-preserved specimen appears 
spotted, the antero-lateral markings taking the form 
of spots or blotches ; the spot immediately behind the 
