9. MICROCHRYSA 193 



2. M. flavicornis Meigen. Antemice yellowish on at least the two 

 basal joints. Legs mainly yellow. Abdomen brilliant green. Frons of the 

 female brilliant green. Thorax with a pale stripe between the humeri and 

 the wing-base. 



An exceedingly brilliant little fly. 



A Very mucli like M. j)olita but smaller and paler. Frons dull greenisli black, 

 ' with less obvious pale pubescence ; face with shorter pubescence Eyes 

 touching for a longer space, and the distinction of the large and small facets 

 even more conspicuous. Antennae with the two basal joints yellowish orange ; 

 third joint smaller than in 31. j^olita and usually brownish orange, though 

 it varies a little in colour. . ^^ ,. 1-1^.1 ^ 



Thorax with still shorter pubescence than in M. pohta, and with the pale 

 pubescence more extended ; humeri and a narrow line along the dorso-pleural 

 suture to the Aving-base obviously yellowish ; postalar calli brownish. 



Abdomen apparently even more brilliant than in M. polita and often with 

 a more coppery tint. GenitaUa brownish orange, not small. , n , • 1 



Legs mainly yellow, but the middle femora have a broad biackish 

 indefinite ring which occupies nearly the middle half, and the hind femora 

 have a still blacker ring which occupies fully the middle two-thirds ; posterior 

 tibice slightly obscured after the middle, and all the tibne less distinctly 

 dilated on the apical half ; tarsi with only just the tip darkened. 



Wings slightly more hyaline and the veins much paler than in lU. ])oUta. 

 Squamaj pale brownish yellow with yellow fringes ; fringe on the alar pair 

 apparently not quite so short, and the fringe on the thoracal pair not quite 

 so long, as in M. imlita- Halteres bright orange. 



9 Frons vivid bluish green, with (in certain lights) a slight narrow pale line 

 running out from each eye part-way across the frons just above the antennse, 

 slio-htly less punctate than in M. polita, and the depression below the 

 ocelli less obvious ; eye-collar still more brilbant green. AntemiJB brownish 

 yellow on the two basal joints • third joint broader and yellowish brown or 

 iH-own ; arista more dorsal than in the male. . 



Thorax with the humeri and the narrow line to the wing- base more 



conspicuously pale. ^ • •. -^i i ^i • 



Abdomen intense bright purplish green. Ovipositor with long thin 



jointed yellow lamellae. . , 



Legs mainly yellow, but with rather more black on the femora than in tne 

 male as even the front femora often bear a small splash, while the middle 

 femora bear a very wide black ring, and the hiiid femora are all black except 

 on the obscurely orange base and at the narrow orange tip. 



Wings almost hyaline, except for the pale yellow stigma and the yellow 



veins. Squamae yellowish white, with similarly colored margins and tringes. 



Length about 4 mm. 



This species varies a little in the amount and in the intensity of the 



yellow on the antennse and legs, but never enough to confound it with 



M. polita ; it also varies in the hue of its brilliant coloring from absolute 



green to beautiful purplish with green reflections, but never towards the 



blackish hue of M. cyaneiventris. My description has mainly contrasted it 



with M. 2)olita, but if. cyaneiventris is distinguished at once by the blackish 



colour of its abdomen in both sexes and by the blackish frons of its female. 



An extremely small female from Chippenham Fen, taken on July 10, 1905, 



has the legs most unusually black and the antennse only obscurely 



brownish yellow about the base, but the pale line from the humeri to the 



wim^-base is distinct and that combined with its size seem to prove that it 



belongs to this species. . jr 7 v 



M. flavicornis is not uncommon and has similar habits to M. ]30iita, 

 with which it sometimes occurs but is by no means so common. I have 



N 



