74 G. FUSCA: DISTINCTIVE CHAEACTERS. 



If a pupa of each species be placed side by side in the position 

 shown in the figures, that is to say with the tumid lips directed 

 upwards, and the more convex surface of what is now the upper 

 extremity of the pupa towards the observer, in such a way that 

 the tumid lips are viewed exactly in profile, it will be seen that 

 whereas the notch between the lips of the pupa of G. hrevi- 

 jjcdpu is relatively wide and shallow, looking something like a 

 wide V,* the corresponding notch in the case of the pupa of 

 G. fmca is narrower, deeper, and distinctly U-shaped. The 

 edges of the tumid lips are also sharper in the latter than in the 

 former species, in which the lips have a decidedly blunter and 

 less cleanly-cut appearance. The breadth of^ the posterior 

 extremity of the pupa (as measured by a horizontal line drawn 

 through the tumid lips when the pupa is in the position indicated) 

 is greater in G. fusca than in G. hrevipalpis, and in the same 

 position the outer margins of the lips in the former are more 

 convex. 



Affinities and Distinctive Characters. 



With Glossina nigrofusca, Newst. (see below, p. 77), G. fusci- 

 pleuris, Austen (p. 75), and G. tahnnifortah, Westw. (p. 81), 

 G. fusca forms an easily recognisable group (which may be termed 

 the Glossina fusca group) of Tsetse-flies, characterised by large 

 size, a general dark brown coloration of the body without con- 

 spicuous bands on the abdomen, and dusky wings. In G. fusca, 

 nigrofusca, and fuscipleuris the palpi (and proboscis) are notice- 

 ably longer than in any other species of the genus ; in G. tabani- 

 formis they are of approximately the same length as in G. hrevi- 

 palpis, Newst. From G. nigrofusca and tahaniformis, G. fusca can 

 at once be distinguished by the fringe of minute hairs on the front 

 margin of the third joint of the antenna, instead of being easily 

 visible when the antenna is examined vinder a platyscopic lens 

 magnifying 15 diameters (nominal), and in length at least equal 

 to one-fourth of the width of the third joint, being so short as to 

 be scarcely noticeable under a lens of the kind mentioned : f the 

 length of the palpi in G. fusca will also assist in distinguishing it 

 from G. tahaniformis. The coloration of the pleurae (which are 

 drab-grey or Isabella-coloured instead of dark grey) and of the 

 hind coxae (which are buff or grey ish-bulF instead of mouse-grey), 

 as well as the greater thickness of the black hairs fringing the 



* See p. 96. t Cf. figs. 18, 19, IC. 



