38 Orthorrhapha brachycera, 



Glypeus shorter or longer, sometimes as loiig as epistoma; it is 

 marked of by a small, transverse keel, and generally bent a little in- 

 wards; it does not reach the lower margin of the eyes. Proboscis 

 slightly or not protruding, of the same size in both sexes, or only 

 very slightly larger in the female. The mouth parts (quadrifasciata) 

 are constructed about as in Sciapus; labrQin broad and high at the 

 base, with a shorter median and two longer lateral teeth, the latter 

 in the natural position lying below the median on account of the 

 semitubular curvature of the labrum. Hypopharynx elongated triangular, 

 curved downwards at the apex, as long as labrum. Maxillary palpi 

 and labium as in Sciapus. There is the difference from Sciapus that 

 the parts are less strongly chitinised, both labrum, hypopharynx and 

 labium, with the basal part, are yellow, only the apex of hypopharynx 

 is black. Thorax rectangular, high, somewhat arehed above; pro- 

 thorax small, with small bristles above, metathorax likewise small, 

 and there is no chitinised metasternum. The thoracic disc has behind, 

 in front of the scutellum, a somewhat, large flat or slightly concave 

 and a little declining area. The acrostichal bristles biserial; there are 

 about six to eight dorsocentral bristles (the number is not constant) 

 increasing in length behind; further a humeral bristle, and often 

 a weaker, a posthumeral, two notopleural, a small præsutural, 

 three supraalar, the two first small, the third long, and a postalar 

 bristle; besides the anterior part of the disc has small hairs, among 

 which the præsutural bristle is sometimes less distinct, and they are 

 also sometimes only slightly marked off from the anterior dorsocentral 

 bristle. There is one or two prothoracic bristles, and generally one 

 or a couple of small hairs above it. Scutellum bare, with two mar- 

 ginal bristles, and generally a small hair on each side. Abdomen 

 long and slender; the first segment is short, and its ventral plate 

 weakly chitinised. In the male there are five, always visible and 

 distinct, dorsal segments, segments two to four of about the same 

 length, the fifth generally smaller, and sixth and seventh, when visible, 

 small, forming a sort of peduncle for the hypopygium, but sometimes 

 hidden. The male abdomen is otherwise variously shaped in the 

 various species; the side margins of the last dorsal segments mav be 

 prolonged downwards in different ways; in most species the fifth 

 segment has on the ventral side two dentiform prolongations, pro- 

 longed more or less forwards, and which together form a sort of 

 cavity for the hypopygium; the other ventral segments are normal. 

 The abdomen of the male is also variously haired in the various 

 species, sometimes the hairs at the sides increase in length towards 

 behind. The hypopygium is free, somewhat large; it is deeply in- 



