326 Orthorrhapha brachyceia. 



coxæ black; the hairs below the femora distinct, but not strong; hind 

 femora with somewhat longer hairs above on the basal part; middle 

 tibiæ with a pair of bristles near the base; the bristle above the 

 apex of the hind tibiæ distinct. Wings a little greyish or brownish 

 tinged; veins black, the last part of the discai vein somewhat curved, 

 much converging towards the cubital vein ; the last part of the postical 

 vein about as long as or slightly shorter than the cross-vein, Squamulæ 

 dirtily whitish or yellowish, with a blackish brown margin and a yel- 

 low fringe. Balteres dirtily yellowish, the peduncle brownish. 



Female. Quite similar to the male; the third antennal joint with 

 the arista subapical, but without any observable excision. 



Length 3 mm. 



This species is very nearly related to dichrocerus and obscurus, 

 but is certainly distinct; from the former it is distinguished by the 

 quite black antennæ and (according to Kowarz's figure) quite another 

 shape of the third antennal joint, and by the want of a bristle in the 

 middle on the middle tibiæ; from the latter by the smaller hypo- 

 pygium of another shape, and finally from both by the smaller size. 



M. melancholicus is very rare, I have only two specimens; one, 

 a male, was bred from a larva taken under the bark of an ash in 

 Hareskov on ^^U 1909, the imago came on '/o (Kryger), the other, a 

 female, was taken at Copenhagen ^/t 1911 (the author); as both 

 specimens agree in every respect I do not hesitate in considering 

 them as the same species. 



Geographical distribution : — The species is hitherto only known 

 from Denmark. 



8. M. ambiguus Zett. 



1843. Zett. Dipt. Scand. II, 456, 18, et 1855. XII, 4616, 18 {Hydro- 

 phonis). — 1857. Loew, neue Beitr. V, 51. — 1862. Schin. F. A. I, "237. 

 — 1877. Kow. Verhandl. zool. bot. Gesell. Wien, XXVII, 65,21. - 1903. 

 Kat. palåarkt. Dipt. II, 337. 



Male. Vertex and frons dark metallic green or bluish green, a 

 little brownish pruinose. Epistoma somewhat broad, metallic bluish 

 green above, steel-blue or somewhat violet below, shining; the trans- 

 verse ridge straight. Proboscis rather thick; palpi black. Occiput 

 black or slightly metallic, a little pruinose; postocular bristles black 

 quite above, whitish below. Antennæ black, third joint longer than 

 broad; arista subapical, a little more than twice as long as the antennæ. 

 Thorax black, slightly greenish or bluish and slightly pruinose, shining; 

 acrostichal bristles short, but somewhat distinct; the dorsocentral 

 rows consisting of some small bristles in front and four longer bristles 



