Dolichopodidae. 171 



2. Hind tibiæ and the greatest part of metatarsus yellow; 

 male with a long costal swelling on the wing, and the 



middle tibiæ thickened and shghtly curved 8. cupreus. 



— Hind tibiæ blackish at the apex and hind metatarsi al- 

 most quite black ; wings in the male without costal swel- 

 ling, and middle tibiæ simple 9. angustifrons. 



3. Wings with a thickening on costa between the basal 

 cross-vein and the apex of the subcostal vein, very di- 

 stinct in the male, slight in the female 4. 



— Wings without thickening on costa 5. 



4. Outer lamellæ of hypopygium yellow ; wings not broad, 

 anterior margin somewhat straight ; hind metatarsi with 



only the apex black 10. celer. 



— Outer lamellæ of hypopygium black ; wings broader than 

 in celer, anterior margin somewhat curved ; hind metatarsi 



chiefly or quite black 11. bfevicor'nis. 



5. Thorax steel-blue ; antennæ pale below the basal joint \^. chalt/beus. 



— Thorax green ; antennæ quite black 6. 



6. Discai vein with the first and second part of about the 



same length; size 3,8 — 4,4 mm 13. metallicus. 



— Discai vein with the first part considerably shorter than 



the second ; size 2,5 — 3,5 mm 7. 



7. Hind tibiæ a little darkened towards the apex; wings 

 somewhat tinged, posterior cross-vein oblique, discai vein 

 somewhat converging towards the cubital vein ; male with 



the epistoma greyish white 14. assimilis. 



— Hind tibiæ quite yellow; wings almost hyaline, posterior 

 cross-vein nearly perpendicular, discai vein slightly con- 

 verging towards the cubital vein, almost parallel with 



it; male with the epistoma black 15. aerosus. 



Subg. Hercostomus. 

 1. H. gracilis Stann. 



1831. Stann. Isis 1831, 255, 44 {Dolichopus). — 1903. Kat. palåarkt. Dipt. 

 II, 311. — DoUchopvs bicolor Macq. 1827. Soc. Se. Lille, 61,6. — 1838. 

 Meig. Syst. Beschr. Vil, 160, 54. — Dolichopus Bohemani Wahlb. 1851. 

 Ofvers. vet. Akad. Fcirh. VIII, 302. — 1855. Zett. Dipt. Scand. XII, 4633, 

 68—69. 



Male. Vertex and frons green, somewhat yellowish brown dusted. 

 Epistoma somewhat narrow, yellow. Palpi reddish. Occiput green, 

 slightly pruinose; postocular bristles yellowish below, black above. 

 Antennæ black, a little elongated, almost as long as the head, the 

 third joint longer than broad, with the lower margin convex, the 

 upper straight, the point thus dorsal, somewhat truncate. Thorax 

 bright green, sometimes golden green, rarely more coppery; generally 

 with a more golden middle stripe; it is somewhat shining; quite 



