204 THE SCOTTISH NATURALIST 



their broadest part nearly as broad as the middle stripe at that 

 part ; thorax and abdomen more distinctly dusted than in the 

 $ ; legs as with the £ in colour and bristling, except that the 

 bristles are stronger, and the mid tibiae possess one antero- and 

 one postero-ventral bristle beyond the middle. 4 h to 5 J mm. 

 Common at Bonhill ; June to September. I have also seen 

 this from New Forest (Adams). 



21. sociella, Ztt, <£. Black; eyes large, frons and jowls somewhat 

 projecting ; eyes narrowly separated ; antennae moderately long j 

 arista nearly bare ; thorax grey dusted, generally with signs of 

 two black stripes on the fore part; sides distinctly pale grey 

 dusted; abdomen distinctly pale grey dusted, dorsal line 

 distinct, anal organ small; legs brownish black, all knees, 

 especially the fore part, distinctly pale yellowish ; mid femora 

 slightly thickened on the basal two-thirds and constricted at the 

 tip, antero-ventral surface with about six weak hair-like bristles 

 to near the middle, at the middle three strong thorn-like bristles, 

 then after a short break a comb-like row of about eight short 

 bristles, the constricted part is bare and at the tip there are 

 about four weak bristles ; postero-ventral surface with nine to 

 ten equally long bristles to beyond the middle, then a break 

 and, as on the other side, about seven longer bristles, and the 

 bare part followed by the three or four tip bristles ; mid tibia 

 irregularly thickened, at a little before the middle slightly 

 thickened, thinning at the middle and then thickened near the 

 tip, pubescence short at the base, but becoming longer at the 

 first swelling and very conspicuous on the remainder of the 

 tibia; antero-dorsal surface with two or three bristles near 

 the apex, the small upper one being the one usually present in 

 other species, the other bristling normal ; hind femora with a 

 row of weak bristles from base to tip, the last two to three 

 stronger on the antero-ventral surface, postero-ventral surface 

 bare ; hind tibia with one dorsal and three fine antero-dorsal 

 bristles, the preapical and antero-ventral bristles absent ; wings 

 greyish, third and fourth veins slightly convergent, outer cross- 

 vein nearly straight, last part of fourth vein two to two and 

 a half times the penultimate ; calyptra pale yellowish, equal ; 

 halteres yellow. 

 ? . Black-grey ; frons hardly one-third of the breadth of the 

 head, parallel-sided ; orbits grey dusted, dull ; middle stripe 

 sometimes red-brown ; thorax and abdomen grey dusted ; legs 

 with all knee-joints distinctly yellow ; mid tibia with generally 



