Chilosia. 



177 



Fig. 89. Head of 

 C. albitarsis d". 



third joint almost broader than long; arista very short-pubescent, 

 almost bare. Thorax bluish black, rarely more dark æneous, sonie- 

 what densely and not quite finely punctate, shining ; it is clothed with 

 long, erect hairs, and besides with shorter 

 hairs, especially distinct on the posterior part 

 and scutellum; the hairs are all black or sonie- 

 times greyish or yellowish at the front mar- 

 gin; there are inconspicuous notopleural and 

 supraalar bristles and more conspicuous post- 

 alar bristles; the scutellar marginal bristles 

 are often rather weak but sometimes stronger 

 and more distinct. Pleura with long, black 

 hairs. Abdomen somewhat parallel-sided, 

 bluish or æneous black, second and third 

 segments dull on the middle, shining at the 

 sides, the fourth segment shining; abdomen 

 is clothed with long, erect, yellow hairs, 

 longest at the sides: just at the front corners of the second segment 

 are generally more or fewer black and somewhat bristly hairs. Venter 

 shining, with long, pale hairs, on the whole middle of third and fourth 

 segments short, black hairs. Genitalia rather large. Legs black, the 

 apex of front metatarsi and the three following joints yellow, the 

 middle tarsi similarly coloured but generally more obscure, and on 

 the hind tarsi the four first joints generally a little pale at apex. 

 Legs mainly black-haired only with white hairs behind middle and 

 hind femora; hind femora densely black-setulose beneath; hind meta- 

 tarsi slightly thickened. Wings yellow, or when quite mature more 

 or less strongly brown tinged, especially towards the anterior margin 

 and the base, which latter is yellow or more or less strongly brown; 

 upper marginal cross-vein curved just above, the upper angle rect- 

 angular. Squamulæ white to yellow with a darker margin and fringe. 

 Halteres orange, sometimes the knob more or less darkened. 



Female. Eyes bare. Frons not broad, widening downwards, 

 trisulcate, but the middle channel often disappearing in the middle; 

 the frons has short, yellow hairs, at the vertex some black hairs. 

 Antennæ almost not larger than in the male, often a little paler. 

 Thorax bluish black or more æneous, densely punctate, with very 

 short, depressed hairs which are all black or more or less mixed with 

 pale hairs; the bristles distinct. Abdomen ovate, bluish or generally 

 æneous, shining; it has short, depressed, yellowish hairs, only erect 

 at the basal corners of second and sometimes also of third segment. 

 Legs with the middle tarsal joints generally less pale than in the male 



12 



