XYLOMYIN^ 



217 



XYLOMYINiE. 



Fig. 153. — Xylomyia marginata i . x S. 



Abdomen with at least seven obvious segments. Antennae with 

 8-annnlated flagellum. Wings with the discal cell emitting three ahnost 

 complete veinlets irrespective of the upper branch of the postical vein, 

 with the fourth posterior cell closed, and with the ambient vein extended 

 beyond the tip of the wing. Scutellum without any marginal spines. 

 Posterior tibiae spurred. 



Head with very slight pubescence. Face depressed on all the middle part as in 

 Leptid(E but without a socketed tubercle. Palpi elongate and upturned so as to lie on 

 tlie depressed part of the face. Eyes well separated in both sexes and almost equally 

 separated from the vertex to the mouthj always bare, and the facets all equal. 

 Antennae (fig. 1 57) elongate ; two basal jomts almost equal in length; third joint 

 (= flagellum) bare, long, and whip-shaped, with eight annulations and usually with 

 a small apical bristle. 



Thorax almost without pubescence, because any that exists is so tiny ; protliorax 

 rather large and rather oblong (fig. 154). KScutellum unarmed. 



Abdomen elongate, with almost parallel sides, and with no angled shoulders on 

 the second segment, composed of from seven to nine visible segments, and practically 

 without pubescence. Genitalia of the male usually large, protruding, and very 

 complicated • of the female with a pair of protruding lamellae. 



Legs fairly stout ; front femora at their origin only moderately distant from the 

 middle pair ; front coxse rather long ; femora simple or with the hind pair incrassate 

 and spinose beneath ; front tibije unarmed, but the posterior pairs with tAvo almost 

 equal fairly long terminal spurs. 



Wings (fig. 153) with an almost Leptid venation. Costal vein extended as an 

 amljient vein to the end of the second veinlet from the discal cell though rather 

 faint after the lower branch of the cubital vein ; mediastinal vein rather abruptly 

 upcurved into the costa opposite the discal cross-vein ; subcostal vein ending about 

 half-way between the mediastinal and radial ; jn-afurca (= common base oi radial 

 and cubital veins) starting ivell before the base of the discal cell and opposite about 



