GLOSSINA 



longitudinal) lie internally the first (anterior) basal cell, and exter- 

 nally the first posterior cell, separated by the anterior transverse 

 vein, which is very oblique. The cubitus i and 2 (fifth longitu- 

 dinal) joins the anterior basal vein, marking out the posterior basal 

 cell, and then runs forwards to join the posterior transverse vein, 

 marking out the discoidal cell, which is hatchet-shaped, with the 

 handle running up to the anterior basal transverse vein. After 

 this the vein turns backwards to join the margin of the wing, 

 deUneating the large second posterior cell. The anal (sixth longi- 

 tudinal) is very short, being unchitinized after meeting with the 

 posterior transverse basal vein, with which it marks out the posterior 

 basal cell. The third posterior cell is, however, shown by its un- 

 chitinized trace . The posterior part of the wing shows an incrassation 

 corresponding to anal 2 and 3. 



The legs are simple, rather long, with long claws and pulvilH. 



The abdomen is flattened, 

 tapering to the apex, and clothed 

 with short black hairs. The male 

 genitalia are characteristic. The 

 ventral plate of the sixth segment 

 carries a patch of dark hairs on 

 each side of the middle line, behind 

 which is the hypopygium, which 

 is oval, tumid, and marked by a 

 vulviform median groove, the 

 anus, running from its anterior 

 margin backwards to beyond the 

 middle. 



The proboscis shows the usual 

 rostrum or conical head projec- 

 tion, the haustellum, or proboscis Fig. 433. — Antenna of a Glossina, 

 proper, and the labellce. showing thi^ Arista. 



The proboscis proper is com- (After Austen, from ' Tsetse-Flies.') 

 posed of labrum, hypopharynx, 



and labium. The labrum arises from the basal bulb of the proboscis 

 in the form of a tube, which is continuous posteriorly with the 

 pharynx, while anteriorly it runs forwards, fonning the dorsal wall of 

 the proboscis. In this position it articulates by means of interlocking 

 teeth with the labium, while, opening ventrally, it articulates with 

 the hypopharynx, which closes the potential ventral opening. 

 Farther forwards it separates from the labium, and ends in a point. 

 The tube composed by the hypopharynx and the labrum is the 

 afferent blood or pharyngeal tube. The hypopharynx starts below 

 the pharynx surrounding the salivary efferent duct, and pierces 

 the bulb of the proboscis, appearing on its dorsal aspect. Farther 

 forward it lies in a groove on the labium, articulating laterally with 

 the labrum. Finally it ends as a delicate chitinous tube just pos- 

 terior to the labellse. Its canal is the salivary tube or hypo- 

 pharyngeal canal. 



