Dolichopodidae. 305 



branch of the postical vein wanting; axillary lobe small and rounded; 

 alula without hairs. The discai vein without any convexity. Squamiilæ 

 with a small angulary lobe, vvith a fringe of somewhat strong hairs, 

 the inner part of squamulæ with longish hairs. 



The developmental stages are not known. 



The species of Achalcus seem to be somewhat ditferent in their 

 habits. A. cinereus occurs at water among reeds, flavicolUs has been 

 taken in sandy localities, or (Zetterstedt. II, 480) "in uliginosis (ad 

 fontes)", while melanotrichus was taken by Mik on ulcerative trunks 

 of AescLilus. A. cinereus is recorded to have two broods in the year. 



Of the genus 3 species are know^n from the palæarctic region; 

 two occur in Denmark. 



TaUe of Species. 



1 . Thorax greyish 1 . cinereus. 



— Thorax yellow or ferruginous 2. flavicolUs. 



1. A. cinereus Walk. 



1851. Walk. Ins. Brit. I, 195, 2 (Rhaphium). — 1878. Mik. Dipt. 

 Unters. Jahresb. k. k. akad. Gymn. Wien, 1878, 21, Tab. I, Fig. 16. — 

 1903. Kat. palåarkt. Dipt. Il, 336. — Rhaphium pijgmaeum Zett. 1855. 

 Dipt. Scand. XII, 4618, 17-18. 



Male. Vertex and frons blackish. Epistoma narrow, whitish. 

 Palpi brown. Occiput dark greyish; postocular bristles whitish. The 

 bristles on vertex yellowish brown. Antennæ about as long as the 



Fig. 96. Antenna of A. cinereus d". X 130. From a dried object. 



head, third joint triangular; the basal joints and the lower part of 

 the third joint yehowish. Thorax dark grey, browni.sh or brownish 

 grey pruinose, slightly shining; the bristles all dark yellowish or fer- 

 ruginous. Pleura dark grey; propleura with a ferruginous bristle. 

 Abdomen dark grey, with very short, brown hairs, and likewise very 

 short hindmarginal bristles, almost not longer on the first segment; 

 they are a little longer towards the apex. Venter grey, with brown 



20 



