XVl] DESCRIPTION 245 



contain the stylet-like epipharynx and the tubular hypopharynx 

 which, by apposition, form a suctorial tube. 



The maxillary palps are slender and as long as the proboscis, 

 round which they form a loose sheath when the insect is resting. 



The wings possess a very striking venation which is quite 

 sufficient in itself to distinguish the genus. The fourth longi- 

 tudinal vein is strongly curved in its proximal portions. The 

 anterior basal transverse vein, at the base of the discal cell, 

 is very short, and this first curve of the fourth longitudinal vein 

 reduces the basal half of the discal cell, whilst the anterior 

 basal cell is correspondingly increased. The fourth vein then 

 bends upwards to join the anterior transverse vein, after which 



An^e^io^ cross-vein t 

 Auxiliary vein 



Fig. 63. Wing of Glossina palpalis to shew the venation. 



it runs obliquely downwards almost at right angles to its 

 former course. After joining the posterior transverse vein it 

 again bends upwards and reaches the margin of the wing some 

 distance before the apex. The second, third and fourth 

 longitudinal veins all turn upwards at their tips and the anterior 

 transverse vein is very oblique. 



The sexes of Glossina can be readily distinguished, as in 

 the male the external genitalia form a large oval swelling, the 

 hypopygium, lying beneath the ventral surface of the seventh 

 abdominal segment. The anus forms a median slit in the front 

 part of this hypopygium and anteriorly on the venter of the 

 sixth abdominal segment is a pair of smaller swellings, termed 



