298 LEPTID^ 



angle but a rather long one below it ; frenum forming a narrow obscure 

 pubescent orange line, Halteres with large dull blackish brown knobs, but 

 with the stem rather blackish orange. 



$ . Very distinct from the male, being much lighter grey in colour. Face 

 (including side-cheeks) very broad, light (almost whitish) grey, and either 

 bare or with a very few scattered black bristly hairs on the epistoma ; frons at 

 its upper part fully half the width of the head and (as well as the vertex) rather 

 densely beset with rather short black bristly hairs which leave the lower half of 

 the margin against the eyes bare as well as a suture which separates the orbits 

 from the occiput and ocellar triangle, and tliese bristly hairs all slope forwards ; 

 back of the head all the way from the jowls to the vertex fairly equal in 

 width, light grey, and bearing fairly conspicuous pale pubescence on the jowls 

 but with numerous short blackish bristly hairs all over the upper part ; palpi 



shorter, drooping at the tip and not so long as 

 the proboscis, blackish grey or light brown, and 

 clothed with moderate yellowish pubescence and 

 sometimes with a few black hairs about the tip. 

 Eyes separated on the frons by about half the 

 Avidth of the head at even the narrowest part 

 which is just above the antennre, though the 

 „ ,„„ ^ , . . frons only gradually narrows from the vertex 



Fig. 197. — Symphoromiiia crasstcornis , .-i • "^ r i ii ^i r i • i 



?. X 30. to this part, and then the lace more obviously 



widens downwards. Antennae much shorter than 

 in the male (fig. 197), but still with the basal joint elongated and dilated and 

 bearing a short rather dense black bristly pubescence ; the antennae some- 

 times have a slightly yellowish or reddish pale grey tinge ; second joint very 

 short but bearing short black bristly hairs above and beneath ; third joint 

 strongly kidney-shaped being quite twice as deep as long with the lower part 

 extending below the second joint more than the upper part extends above it. 



Thorax light grey, usually but not always with four blackish grey stripes 

 (because the middle dark stripe is almost always split into two) ; Avhen present 

 the middle dark stripe (or double-stripe) does not extend so far back as the 

 side stripes. Pubescence much shorter than in the male, and rather yellowish 

 about the humeri. 



Abdomen conical, light grey, and not at all compressed ; the four basal 

 segments nearly equal in length, the fifth about half as long, and the 

 sixth and seventh each about half as long as the fifth. Pubescence on the 

 hindmargins and sidemargins rather long and yellowish, but on the disc 

 shorter blacker and more bristly. Ovipositor with a pair of widely spread 

 out lamellae. 



Legs Avith all the tibiae dull dark ferruginous. Pubescence rather con- 

 spicuously pale yellow on the front coxae but less obviously so on the others, 

 slight and partly pale on the femora, and with no longer postero-ventral 

 ciliation on the hind tibial. 



Wings with a browner tinge ; veins orange about the basal half and only 

 brownish on the rest. 



Length about 7 mm. 



This species does not vary to any important extent, and should not be 

 confounded with any other (unless S. grisea be allied) though it is a rather 

 inconspicuous-looking fly. 



S. crassicornis is apparently a mountain species as it occurs freely in 

 the Scotch Highlands (Strathblane, Eannoch, Aviemore, I^ethy Bridge, 

 Nairn, Spey Bridge, Banff, and Tongue), and also at Aherlady, Kirkmuir- 

 hill in Lanarkshire, and in the Lake District. I have further records 

 from Dolgelly, Herefordshire (probably the Black Mountain), Lancashire 

 (Rivington), and Durham. Beling found the larvre in earth beneath turf 

 on a cart-road near a wood. My dates extend from June 24 to July 29. 

 It is recorded from extreme North Europe to Italy. 



