588 THEREVID^ 



large and broad, rounded oblong, about half as long as the upper plate, 

 and bearing where they approximate ventrally a fringe of long stiff black 

 hairs, while the rest of these lamellae and also the upper plate bear obvious 

 though not abundant pale yellow stiff depressed hairs ; all the inner processes 

 of the genitalia are bright dark orange. 



Legs probably blackish brown but the femora rendered light greyish by 

 whitish dust and adpressed pale scaly pubescence, and the end of the femora 

 and all the tibiae except the blackened tip orange, while the basal joint 

 of all the tarsi except its tip and a good deal of the second joint are also 

 orange ; coxae glossed silvery, with moderately long whitish pubescence, and 

 the anterior pairs with two black bristles in front near the tip, while the hind 

 pair have one black bristle on the outside not quite so near the tip besides 

 two smaller ones in front at the tip ; femora without bristles except two or 

 three small black ones beneath the middle pair near the tip and a row of 

 about eight very small black ones beneath the hind pair and about three 

 rather larger antero-ventral bristles also on the hind pair ; front tibiae with a 

 row of about four small dorsal bristles and two posterior ones, besides the 

 apical spines of which an anterior one is the longest ; middle tibiae with four 

 rows of three or two spines besides the strong apical circlet, and the hind 

 tibiae with similar but more numerous spines ; tarsi all with a few short stout 

 black bristles and a circlet of short spines at the tip of the first four joints 

 growing shorter after the basal joint. Pulvilli dull orange ] claws small, 

 blackish. 



Wings with an obvious yellow tinge which becomes conspicuous about the 

 base and foremargin, but with no cloudings ; veins yellowish ; fourth posterior 

 and anal cells closed close to the wingmargin. Squamae glassy, with a broad 

 yellowish white margin on which there is no fringe except a slight pale one at 

 the end which mixes itself up with the metapleural tuft. Halteres orange, 

 but with the base of the knob darkened. 



9 . Very different from the male. Frons barely one-eighth the vndth of the head 

 at the vertex but widening to double that width at the antennae, dark brown 

 on the upper two-thirds and with narrow bare side-channels just before the 

 very narrow orbits and bearing on all this part (except on the channels) rather 

 numerous short black forwards-directed bristles, but silvery on the front third 

 and bare unless two or three of the short black bristles straggle forward on to 

 it, and this silvery part has a very narrow depressed middle line ; face all 

 quite bare, silvery with a large middle mouth-opening which leaves only 

 narrow sides and which extends almost up to the base of the antennae ; jowls 

 and lower part of the back of the head with rather long white pubescence as 

 in the male ; back of the head more sUvery than in the male and more equally 

 inflated from the eyes, and with the black bristles more numerous and arranged 

 in two irregular rows of which the hinder row is well out on the occiput ; 

 collar whitish grey, with less strong bristles • palpi larger and bearing more 

 obvious pale pubescence. Antennae as in the male but more dusted with 

 whitish grey. 



Thorax not so light grey, and with the three dark stripes broader and 

 more obvious ; middle stripe with a faint very narrow dividing line on the 

 fore part and not so narrowly continued to the hindmargin ; pubescence com- 

 posed of rather more abundant adpressed short black bristly hairs except 

 about the sides, where some similar but thinner and yellow hairs occur, and 

 there is a small tuft of a few longer erect whitish hairs behind the postalar 

 calli ; pleurae with only very short inconspicuous pale pubescence except on 

 the metapleural tuft which is composed of white hairs with sometimes a few 

 stronger black ones on the back part. Scutellum light grey, but greyish 

 black on the disc near the thorax. 



Abdomen long and slender, twice as long as the thorax, with eight dorsal 

 segments, of which the last five are almost equal in length, and the last two 

 rather tubidar, almost bare, and shining black with five or six pairs of rather 

 silvery white side spots ; basal segment greyish brown with the hind corners 

 widely greyish white ; second and third segments shining black with a large 

 triangular silvery white spot at each hind corner of which one side runs along 

 more than one-third of the hindmargin and another side occupies all the side- 



