Dolichopodidae. 377 



long, erect, straight spine, and towards the apex a downwards curved 

 bristle or spine ; posterior femora with a preapical bristle ; hind meta- 

 tarsiis a little shorter than the second joint, with hairs and small 

 bristles below. Wings about hyaline; veins black; costa with a 

 thickening as in spinigerellus. Squamulæ yellow, with the extreme 

 margin black and a black fringe. Balteres yellow. 



Female. Epistoma less narrow than in the male. Legs simple 

 and without special bristles; middle tibiæ with one ventral bristle; 

 hind femora very slightly darkened above at the apex and hind tibiæ 

 yellow; hind metatarsus of the length of the second joint. Wings 

 without costal thickening. 



Length 1,6 — 1,9 mm. 



This species is very similar to spinigerellus, but it is in the male 

 at once recognised by the different ornamentation of the hind tibiæ. 

 The fernales are very like each other, monacanthns is best distinguished 

 by the green, a little pruinose frons, this being blue and shining in 

 spinigerellus; also the posterior or middle coxæ are as a rule more 

 or less greyish in monacanthus, while they are generally yellow in 

 spinigerellus. The length of the hind metatarsus seems also to give a 

 character, as I find it shorter than the second joint in spinigerellus^ 

 and of the same length in monacanthus; this is somew^hat curious, 

 for in the male of spinigerellus the two joints are of about equal 

 length, while in the male of monacanthus the metatarsus is a little 

 shorter than the second joint. 



T. monacanthus is rare in Denmark, and was not known as 

 Danish until this year (1912), when I took 9 males and one female 

 on ^V? — ^^h at Faxe Ladeplads; they occurred at a ditch together 

 with spinigerellus, and they were seen sitting on the water and flying 

 quite low over it, behaving quite as spinigerellus. 



Geographical distribution: — Middle Europe down into Bohemia 

 and Hungary; its northern limit is in Denmark and it occurs in 

 England. 



3. T. signatus Zett. 



1849. Zett. Dipt. Scand. VIII, 3065, 9—10 (Chrysotus). — 1903. Kat. 

 palaarkt. Dipt. II, 347. — Medeterus signatus Stæg. in litt. 1849. Zett. Dipt. 

 Scand. VIII, 3096, Obs. 



Male. Vertex and frons green. Epistoma narrow downwards, 

 white. Palpi brownish. Occiput greenish, greyish pruinose; postocular 

 bristles blackish above, paler downwards. Antennæ black or brownish 

 black. Thorax green or a little bluish green, slightly pruinose. Pleura 

 green or bluish, a little greyish pruinose. Abdomen green, with short, 



