Dolichopodidae. 327 



behind, longest backwards, Scutellum with four bristles. Pleura dark 

 bluish or bluish green, grey or dark grev pruinose; propleura with 

 three or four yellowish protiioracic bristles. Abdomen black, slightly 

 greenish or bluish, shining; it is clothed with short, black hairs, and 

 has longer hindniarginal bristles on the first segment. Venter greyish 

 pruinose. Hypopygium somewhat large, black; the eighth segment 

 slightly pruinose, with some pale hairs; the ventral lobes somewhat 

 long, straight, a little dilated at the end; the outer lamellæ short, 

 somewhat triangular, hairy; both pairs brownish or blackish brown. 

 Legs quite black, coxæ grey, especially the front coxæ whitish grey, 

 almost silvery pruinose anteriorly; hind metatarsus a little more than 

 a third part of the second joint, a httle excised at the base. The 

 legs have short, blackish or dark brown hairs; the bristly hairs on 

 the anterior coxæ and the bristle on the hind coxæ whitish; the hairs 

 below the femora short and indistinct, pale, hind femora with longer 

 hairs above on the basal part; middle tibiæ with a pair of bristles 

 near the base, hind tibiæ here with a small bristle. Wings hyaline 

 or very slightly tinged; veins black, the last part of the discai vein 

 slightly curved or almost straight, somewhat converging towards the 

 cubital vein; the last part of the postical vein as long as or almost 

 as long as the cross-vein. Squamulæ dirtily yellowish, with a blackish 

 brown margin and a yellowish or pale brownish fringe. Halteres 

 brown or blackish brown, especially the knob dark above. 



Female. Quite agreeing with the male; abdomen a little pruinose 

 at the sides. 



Length 3,2 — 3,7 mm. 



M. ambiguus is rare in Denmark, we have only two specimens, 

 a male taken in Grib Skov on ^^/e 1911 (Kryger), and a female taken 

 in Tyvekrog, the southern part of Grib Skov, on V;i 1907 (the author) ; 

 it was taken on tree-trunks, 



Geographical distribution: — Northern and middle Europe down 

 into France; towards the north to middle Sweden, 



9. M. infumatus Loew. 



1857. Loew, Neue Beitr. V, 52. — 1862. Schin. F. A. I, 238. — 1877. 

 Kow. Verhandl. zool. bol. Gesell. Wien, XXVII, 66, 22. — 1903. Kat. 

 palåarkt. Dipt. II, 338. — Hydrophorus muralis 1843. Zett. Dipt. Scand. II, 

 455, 16, p. p. var. a et b. 



Male. Vertex and frons dark, brownish pruinose. Epistoma like- 

 wise dark, brownish pruinose above, black and shining below. Palpi 

 black. Occiput black, a little greyish pruinose; postocular bristles 

 yellowish, the uppermost are black, and likewise generally one or two 



