474 



UNITED STATES NATIONAL MUSEUM BULLETIN 2 24 



Small to medium size flies. The face has a small 

 gibbosity with a moderate number of stout bristles. 

 The postmesonotal dorsocentral bristles are strong. The 

 antennal style is long, the thoracic and abdominal pile 

 short. The tergal bristles are little more than long, 

 stiff setae, except those of the first tergite. The female 

 ovipositor is robust, short and cylindrical. These flies 

 are especially characterized by having a short spur ex- 

 tending back from the base of the anterior branch of 

 the third vein. Length 15 to 20 mm. 



Head, lateral aspect : The face is moderately promi- 

 nent below, the greater part of this is due to the re- 

 cession of the eye. It is very shortly and slightly 

 produced on the upper half and slightly concave. The 

 eye is moderately recessive anteriorly below. The oc- 

 ciput is moderately thick, least thick in the middle and 

 well developed at the vertex ; it gradually slopes down 

 to the eye margin. The pile of the occiput is restricted 

 to a few fine hairs dorsally and in the middle ; the ven- 

 tral third of the occiput bears numerous, long, delicate, 

 curved, bushy hairs. Bristles begin at the middle, are 

 moderately stout and near the vertex become especially 

 stout, short and slightly curved; there are 5 strong, 

 middle bristles ; the intervening bristles are somewhat 

 weaker and there are 7 or 8 stout bristles above. The 

 proboscis is small, of moderate girth, cylindrical, with 

 dorsal ridge, obtuse apex, and some long, stiff hairs 

 ventrally l^low. Palpus of 1 segment bearing apically 

 numerous, strong, downward curved bristles and bristly 

 hairs. The antenna is attached at the upper third of 

 the head and of moderate length ; the first segment is 

 not quite twice as long as tlie second, the second slightly 

 widened apically. The third segment is oval, gently 

 tapered from the middle towards the apex, and nearly 

 as long as the first two segments combined. A minute 

 microsegment is present and the style is moderately 

 long with short, apical bristle, attenuate along the 

 middle, and nearly 11/2 times as long as the third seg- 

 ment. The third segment is laterally compressed. The 

 fii-st segment bears 8 or 10 setae above and longer setae 

 below ; second segment with 5 or 6 setae dorsally and 

 a like number below ; third segment with 1 or 2 minute 

 setae. 



Head, anterior aspect : The face below the antenna is 

 a fourth of head width and slightly divergent below ; 

 subepistoma of moderate size, oblique, plane and pubes- 

 cent. The face is pubescent, with some short, fine, scat- 

 tered pile across the middle, 12 moderately strong, long, 

 black bristles in the middle of the face on the lower 

 half, and with an additional 3 pairs of longer, stouter 

 bristles on the anterior epistomal margin and 3 stout 

 pairs along the lateral margin. The front is slightly 

 divergent; the vertex is equally convergent, its sides 

 have 4 or 5 distinct, slender bristles. Vertex moderately 

 excavated with slanting sides, small ocellarium and 3 

 pairs of weak bristles. Eyes enlarged centrally. 



Thorax : The thorax everywhere pollinose ; the pile of 

 the meson otum is scanty, fine, nearly erect and setate; 

 a double acrostical row of setae is present anteriorly; 



dorsolateral elements are weakly differentiated and at 

 the wing level become long and strong with 4 in each 

 row. Humerus ijilose. Lateral bristles are long and 

 stout and consist of 2 notopleural, 1 supraalar, 2 post- 

 alar, and 2 pairs of scutellar bristles. Scutellum thick 

 and convex but without impressed rim. Propleuron 

 with dense, long pile, the pronotum has 4 pairs of stout 

 bristles. Upper mesopleuron with a few fine hairs and 

 posteriorly with several, long, fine, bristly hairs; simi- 

 lar hairs present on the upper stemopleuron and 

 shorter, fine hairs present on the pteropleuron. Post- 

 hypopleuron with 6 slender, quite weak bristles; meta- 

 pleuron with a single row of 6 stout, ventral bristles 

 and 4 or 5 slender, dorsal bristles. Metanotal slopes 

 pubescent only. Anterior basalare with several, long, 

 bristly hairs; squama with a multiple fringe. Post- 

 metacoxal area membranous ; prostenium dissociated. 



Legs : The hind femur is stout, its tibia comparatively 

 slender; anterior and middle femora slightly elongate 

 and slightly swollen towards the base. All bear dense, 

 appressed, setate pile on all surfaces, and the bristles 

 are stout and moderately long ; the hind femur bears 1 

 stout, dorsomedial, 1 apical, and 1 subapical bristle; 3 

 dorsolateral, 2 of which are in the middle and 1 is sub- 

 apical ; also 5 oblique, ventrolateral, and 2 ventromedial 

 bristles at the base. Hind tibia with 4 weak, dorso- 

 medial, 3 strong, dorsolateral, and 2 ventrolateral ele- 

 ments beyond the middle. Basitarsus stout, as long as 

 the followmg three segments. Middle femur with 2 

 posteroapical, 2 anterodorsal, 2 anteroventral and 3 pos- 

 teroventral bristles on the basal half. Middle tibia 

 with 2 minute, or weak dorsal bristles on each side on 

 the outer half, 2 long, strong, anteroventi-al, 1 equally 

 strong ventral at the outer third, and 3 or 4 postero- 

 ventral bristles. Anterior femur with only quite weak, 

 small, ajDical bristles and about 9 or 10 long, fine, bristly 

 hairs below; its tibia has 5 or 6 weak doi"sal elements 

 but with a conspicuous, posteroventral row of 3 long, 

 stout, oblique bristles and a fourth shorter bristle at the 

 apex ; apical circlet of 8 bristles. The posterior bristles 

 of the tarsal segments are quite long and stout; tarsi 

 end in wide, spatulate, long, apically rounded pulvilli, 

 long, stout empodium, long, slender, sharp, apically 

 bent claws. 



Wings: Marginal cell closed with a long stalk and 

 this cell curved slightly backward apically ; the anterior 

 branch of the third vein ends far above the wing apex, 

 the posterior branch ends beliind the whig apex. First 

 posterior cell narrowed in the middle but the second cell 

 is only slightly swollen at tlie base; lower end vein of 

 the discal cell pulled backward. Fourth posterior cell 

 closed and stalked, convex apically and distally. Anal 

 cell closed and stalked. Second basal cell ends in two 

 veins ; alula large ; ambient vein complete. 



Abdomen: The abdomen is subcylindrical and 

 strongly tapered; the second tergite is as wide as the 

 mesonotum and rather flattened ; abdomen as long as the 

 wings. The first tergite is strongly swollen and convex 



