146 Orthorrhapha brachycera. 



hind femora at tlie base with long hairs which vary from yellow to 

 whitish grey; on the femora they are more or less intermingled with 

 black hairs, sometimes quite black, especially on the front femora. 

 Wings somewhat yellowish brown tinged, especially towards the 

 anterior margin; veins dark yellow to brown, the base of the cubital 

 fork, the medial cross-vein, the part of the discai vein from the cross- 

 vein to the end of the discai cell, the veins closing the cell apically 

 and the basal part of the upper branch of the postical vein more or 

 less brownish seamed, but generally only to a slight degree; the 

 fourth posterior cell closed. Stigma yellow. Halteres brownish black. 



Female. Vertex and frons yellow pruinose with black hairs, 

 cheeks and jowls whitish pruinose with white hairs; on the jowls, at 

 the lower eye-margin a tuft of black hairs; all the hairs shorter than 

 in the male. Frontal cailus large, somewhat convex, of a cordate 

 shape, it is incised below, somewhat truncate above and reaches the 

 ocellar tubercle. The erect, black and depressed, yellow hairs on 

 thorax short; the two longitudinal stripes generally distinctly visible; 

 the hairs on sterna and pleura white. Abdomen black, the first seg- 

 ment somewhat greyish; at the hind margin of the following segments 

 a distinct, whitish grey, on the anterior segments sometimes more 

 yellowish, transverse band, narrowest in the middle; the seventh seg- 

 ment shining black. The first four segments clothed with depressed 

 hairs which are black on the black parts, yellow to whitish on the 

 grey bands ; the hairs are somewhat longish at the hind margin of 

 the first segment; the last segments have short, erect, black hairs, 

 the fourth segment both depressed and erect hairs. Venter with long, 

 pale hairs on the first three segments and with short, black hairs on 

 the last four segments. The hairs on the femora shorter than in 

 the male. 



This species, as seen from the description, varies somewhat in 

 the colour of the hairs; lirstly, the yellow hairs vary from deep yel- 

 low to greyish yellow or whitish, and secondly, the clothing on the 

 dorsal side of abdomen may be quite black, or yellower at the sides; 

 also, the hairs on the anterior femora may be more or less inter- 

 mingled with black so as to appear quite black. In spite of this 

 variation it is recognized especially by the pale yellowish or whitish 

 hind margins of the segments and the grey, transverse bands; the 

 female is distinguislied by the large frontal callus. 



Length 8—12 mm. 



Remarks: In this species I have sometimes found the fourth 

 posterior cell more or less open in both sexes; in a single case the 

 cell was rather broadly open. 



