194 [September, 



98 (99) Hind tibife of male curiously shaped, looking as if rather more than its 



lower third had been pared or cut away, leaving a flat triangular 



surface behind {fig. 6). 



i . Thorax and abdomen black ; froiis black, scarcely shining, about one-third 



broader than lonsr, upper supra-antonnal bristles small, under ones minute, 



^ _ palpi pale yellow, with the bristles short ; 



Hf^^°j^^^^^'?^r^y?*<i;s,^^^^ wings nearly clear, costa about to middle of 



^•-'^^^ "iii^jfi ■' , --_I^-Nj wing, 1 double 2, angle at fork moderate, Ist 



thin Vein leaves at fork with a very gentle curve, 

 *'^" ^- fringe fairly long ; legs yellow, upper portion 

 of hind tibioo furnished with three or four long and slender appressed hairs ; 

 abdomen long and slender, the curious hairs, though finer, are longer both 

 relatively and absolutely than in rufipes ; hypopygium hidden in the only 

 specimen before me, but the yellow anal organ is lai-ger than in rufipes, and 

 without its upward tilt f mm. hirtiventris, n. sp. 



99 (98) Hind tibiie simple. 



<J $ . Thorax and abdomen black ; frons black and dull, nearly twice as broad as 

 long, supra-antennal bristles very large, the under pair lying close against the 

 upper pair, and equalling them in size, palpi yellow, with bristles of ordinary 

 length ; wings nearly clear, particularly in male, costa to middle of wing or 

 barely, fringe very long, 1 double 2 ((?) but less ( ? ), angle at fork moderately 

 large ( c? ), acute ( ? ), 1st thin vein leaves at the fork with only a gentle curve ; 

 legs light brown, darker towards tip of hind femora ; male abdomen slender, 

 the characteristic hairs are absent from the dorsum, except on the hind margins 

 of the segments ; the hypopygium short and prolonged into a kind of nose 

 beneath the anal organ, clothed on the sides with the same sort of hairs as the 

 abdominal ones, subanal body small and usually exposed, the yellow ventral 

 plate large and square-shaped, the slender anal oi'gan yellow or dusky, and with 

 an upward tilt 2^ — 3 mm. rufipes, Mg. 



100 (97) Male abdomen without such hairs. 



100 (101) Hind tibise of male shaped as in hirtiventris. 



<J ? . Thorax and abdomen black ; frons about one-third broader than long, 



slightly shining, upper supra-antennal bristles small, under ones minute, palpi 



yellow, and with bristles of ordinary length ; wings nearly clear, fringe fairly 



long, costa barely to middle of wing ( S ) more acute ( ? ), 1 about three times as 



long as 2, angle at fork moderate (S), fully ( ? ), 1st thin vein leaves at the fork 



with a gentle curve ; legs yellowish, femora with dusk upper and lower margins, 



hind femora stoutish, darkened towards apex, and with longish hairs on the 



basal half of under-side in both sexes, the flattening of the hind tibiae {$) 



limited to the lower third, the upper portion without the long appressed hairs 



present in hirtiventris, hind tibiee (?) simple, though the upper margin is 



slightly deflected outwards when the alteration of form begins in the other 



sex ; but two or three segments of male abdomen somewhat hairy, as in 



humilis ; and hypopygium armed with bristles in much the same kind of way, 



viz., with a bunch at each lower corner, and three or four others on the sides 



placed diagonally, the yellow anal organ short and stout. 



I5 — If mm. derasa, n. sp. 



