234 TH E SCOTTISH NATURALIST 



length, arista bare; thorax black, rather shining, slightly 

 dusted with grey ; abdomen distinctly pale grey dusted, dorsal 

 line distinct, dilated on each segment, anal organ moderately 

 large j legs black, fore knees hardly paler j mid femora with a 

 row of about ten bristles on the basal two-thirds, the last three 

 closer and shorter but stronger, a row of about eight short 

 bristles on the base of the apical third, and near the tip three 

 or four weaker bristles ; postero-ventral row somewhat similar 

 but longer j mid tibia thickened on the apical half, pubescence 

 increasing in length from near the base to tip, bristling normal ; 

 hind femora with a row of bristles, about nine, from before 

 the middle to the tip increasing greatly in size as they advance, 

 a somewhat similar row of rather finer bristles on the postero- 

 ventral surface ; hind tibia with the usual four bristles ; wings 

 brownish, last portion of fourth vein about two and three- 

 fourths the penultimate ; calyptra brownish or yellowish, equal ; 

 halteres yellow. 



$ . Very close in general appearance to the $ of serena and 

 parva. From the former it differs in having the orbits 

 entirely pale grey dusted and without any perceptible gloss 

 behind ; from a'erea it differs in having the middle stripe much 

 less distinctly dusted when seen from in front, the basal ventral 

 mid femoral bristle is present ; the thorax is black-grey ; the 

 acrostichal bristles are two-rowed ; the lower fronto-orbital 

 bristle is nearer the eye-margin than it is to the middle stripe ; 

 and the orbits are at least as broad as the middle stripe at its 

 narrowest part ; otherwise as the S > except that there are only 

 two long bristles at the tip of the hind femora, antero-ventral 

 side. (Stein does not describe the ? , but his ? of parva is 

 very close to this. I have not been able to obtain this species 

 for comparison.) 3 to 4 mm. 



A very common species at Bonhill and Cardross; May 

 to August. The ? described was one of two pairs taken in 

 cop. I have also seen this species from Aberlady (Carter), 

 New Forest (Adams), and Oxford (Hamm.). 



29. serena, Fin., <£ . Very similar to the foregoing, differing 

 principally in the bristling of the mid and hind femora; the 

 antero-ventral row on the former has at most five or six long 

 widely placed rather weak bristles on the basal half and a 

 continuous row of about twelve on the apical, of much weaker, 

 shorter bristles, those on the constricted part of the femora 

 being; the shortest j the mid tibia is much as in postica, but 



