22 



process short and spine-like. Female with signum of the uterus 

 consisting of a single chitinous plate, the long axis transverse and widest 

 in the distal third. 



" Male. Length, 10-11 -9 mm. ; proboscis, 2-3-2-8 mm. ; width of 

 head, 3 -2-3 -3mm.; front at vertex, 0-6-0-7 mm. ; wing, 11-12 -4 mm. 



" Female. Length, 12 -5 mm. ; proboscis, 3-1 mm. ; width of head, 

 3 -5-3 -6 mm. ; front at vertex, 0-75-0 -8 mm. ; wing, 13 -2-13 -6 mm. 



"Male. Head with the posterior surface 'mouse-grey' (Austen), 

 antennal cavity pearl-grey, sometimes with a pale vinous tinge ; ocellar 

 spot and frontal stripe unicolorous pale brown ; antennae with the 

 distal two-thirds of the third segment infuscated, the rest pale buff ; 

 outstanding hairs on third segment short, about one-sixth to one- 

 seventh the width of the segment. Proboscis bulb pale translucent 

 buff-yellow, the upper lateral margins brownish or orange-brown, 

 ventral median suture proximally, dusky to orange-brown. Thorax 

 with the usual distinctive colour and markings ; sterno-pleurae more 

 or less infuscated ; scutellar bristles long. A bdomen : Dorsum of 

 first and second segments light brown ; the remaining segments, 

 together with the lateral margins, dark brown (' mummy-brown/ 

 Austen), the distal angles either unicolorous with the rest of the 

 abdomen or slightly paler. Legs : Light or dusky ochraceous-buff ; 

 leg I. with the femora infuscated on the upper half of the inner 

 surface, tips of the last two segments dark brown or black ; leg II. 

 with the tips of the last two segments generally more strongly 

 marked than in I. ; leg III. with the last two segments entirely 

 dark brown or black, paler beneath, proximally. Wings with the 

 thickened portion of the anterior transverse vein scarcely darker in 

 colour than the rest. 



" Female. Colour and pattern similar to that of the male ; but the 

 distal segment of the abdomen usually paler." 



This species, like the foregoing, occurs in Belgian Congo, the original 

 series of specimens having been taken by Dr. J. Schwetz on the River 

 Kwango (on the frontier of Angola), at Kasongo Lunda and in the 

 neighbourhood of Kundi, 24-25. x. and l.xi.1920. According to its 

 discoverer, on descending the river by boat, he " came to a region 

 abounding in this species," and also in G. palpalis. The only 

 other field-note recorded is to the effect that some of the examples 

 of G. schwetzi, of both sexes, were captured on the ground (in the 

 case of two males, on a path) in the evening. 



After concluding their description of G. schwetzi, the authors write : 

 " In its general external facies the male of this species bears a striking 

 resemblance to that of Gl. tabaniformis, West. ; the female, on the 

 other hand, owing to the darker colour of the thickened portion of the 

 anterior transverse vein, might easily pass as a specimen of Gl. brevi- 

 palpis, Newst. Both sexes may, however, be readily distinguished 

 from any other members of the ' Fusca Group ' by the strikingly 

 characteristic genital armature. Furthermore, the antenna of Gl. 

 schwetzi can be distinguished from that of Gl. tabaniformis by the shorter 

 fringe of fine hairs on the anterior edge of the third segment." 



In assigning G. schwetzi, as they do, to Newstead's " Fusca Group," 

 the authors of this species are, of course, perfectly correct ; but since 

 this Group, as has been shown above (see p. 7), is coextensive with 

 the G.fusca and G. brevipalpis Groups (Groups III. and IV.) of Austen's 

 system, which is followed in this book, the species is perforce dealt 

 with here. 



