156 THE SCOTTISH NATURALIST 



one-fifth; middle stripe black or brownish, orbits silvered, 

 middle stripe above the antennae twice the breadth of the 

 orbits ; abdomen more pointed, less flattened, and without the 

 dorsal stripe ; fore legs not so much blackened as in the <$ ; 

 the hind tibia carry on the antero-ventral surface an alternately 

 arranged row of about seven bristles, those on the uppermost 

 row stronger than the under, the other bristling as usual; 

 wings more rounded than in the £ . 8 to 10 mm. 



This is the largest species of the genus. It is generally 

 distributed, and not uncommon. I have seen it at Bonhill 

 in hundreds, hovering much as the Syrphida, in the shade 

 of the trees in a beech wood, May to June. (The abdomen is 

 sometimes testaceous.) 

 2. fuscula, Fin., £ . Black; frons, epistome, and jowls hardly pro- 

 jecting; frontal stripe rather broad for a $ of this genus, 

 middle stripe matt black, orbits silvered; antennae shorter 

 than the face, arista slightly pubescent ; thorax black, shining, 

 sides whitish grey dusted ; dorsum viewed from behind with 

 generally two rather indistinct stripes on the fore part, pleurae 

 armed as in hamata ; abdomen nearly parallel-sided, distinctly 

 grey dusted, the dorsal stripe interrupted at the hind margin 

 of the segments and not with marked triangular dilatations; 

 anal organ moderately large ; legs black, the hind tibia, the mid 

 tibia except the base, and the fore tibia yellowish or brownish ; 

 mid coxa armed as in hamata ; mid femora bristled much as in 

 hamata; mid tibia hardly thickened on the apical half, 

 pubescence on the ventral surface very short on the basal 

 portion, but longer on the tip half, not so erect as in hamata 

 and much more indistinct, the usual bristles present ; bristling 

 of hind femora not remarkable ; hind tibia bent, fringed with 

 hairs as in hamata, but much shorter in comparison, and the 

 antero-ventral row more bristle-like; the usual two dorsal 

 bristles present; the antero-dorsal surface carries five or six 

 bristles, the lower one the strongest ; wings greyish, third and 

 fourth veins convergent, outer cross-vein bent, last portion of 

 the fourth vein about one and a half times the penultimate ; 

 calyptra unequal in size, yellowish ; halteres yellow. 

 ? . Similar in colour and general appearance to the £ ; eyes 

 separated by about one-third the breadth of the head at the 

 antennae and by one-fourth at the ocelli ; middle stripe matt 

 black, at its broadest part about three times the breadth of the 

 orbits at that part ; orbits silvered, narrowed in front ; abdomen 

 not so distinctly dusted as in the £ , more pointed, and with 



