312 



Syrphidae. 



some united hairs; after this there are about six black, isolated bristles, 

 the basal one or two sometimes yellovv; below there are shorter, 

 yellow hairs; front tibiæ somewhat evenly dilated from the base, with 

 the posterior apical corner drawn out ; the posterior margin is almost 

 straight without any incurvation; the tibiæ are whitish 

 towards the apex, below there are a pair of incon- 

 spicuous, blackish, longitudinal markings and just at 

 the apex a couple of black transverse lines; the hairs 

 are short and pale; front tarsi not much dilated and 

 evenly decreasing towards apex, the basal joint about 

 as long as the three foUowing. Middle trochanters 

 with inconspicuous black bristles at apex; the middle 

 femora as in scambus with an irregular row of short, 

 black bristles on the anterior side towards below not 

 reaching the base ; below the apex two or three of 

 the curious, recurved hairs; on the ventral side about 

 the middle some bristly but, at all events generally, 

 yellow hairs and on the posterior side shorter, yellow, 

 or towards the apex black, hairs ; middle tibiæ shaped 

 somewhat as in scamhus, with distinct, yellow fringes 

 on the ventral margins in the basal half, longest on 

 the anterior side; hind femora with longish, pale hairs 

 P.immarginatusd, on the antero-ventral side, hind tibiæ short-haired ; 

 right front leg j^j^j^j metatarsus a little thickened. Wings somewhat 

 strongly brownish tinged. Squamulæ smoky with a 

 yellow fringe. Halteres yellow. 

 Female. Frons broad, æneous, with two triangular, yellowish or 

 somewhat greyish dust spots, connected broadly at the eye-margin 

 with the pruinosity on epistoma, the spots are not well defined such 

 as they are in scambus; frons yellow-haired, with dark hairs in front 

 of the ocelli; the hairs on epistoma short and not dense. Thorax 

 short-haired. Abdominal spots considerably smaller than in the male, 

 and hence the middle and transverse black lines much broader; the 

 spots somewhat rounded inwards; fifth segment with large spots, sixth 

 quite or almost quite yellow; the abdominal spots are smaller than 

 in the female of scambus, especially the basal pair. Legs with only 

 faint dark rings or markings on hind femora and tibiæ, hind meta- 

 tarsus more or less darkened, the last two joints blackish; middle 

 tibiæ with slight traces of the shape in the male. Anterior femora 

 with quite short hairs behind, and front femora with the pecuHar, 

 white hair at the base, but it is straight. Squamulæ yellow. 

 Length 7,r,— 8 mm. 



Fig. 106. 



from below. 

 X 20. 



