ROBBER FLIES OF THE "WORLD 



543 



bluntl}' pomted. The occiput is moderately thick but 

 only through the middle and lower portion; on the 

 upper third it recedes to the eye level ; pile almost ab- 

 sent on the upper half, but more abimdant below and 

 rather long; bristles begin in the middle, where there 

 are 5 or 6 weak to moderately stout pairs ; on the upper 

 third there are about 7 or 8 rather long, scarcely curved, 

 exceptionally stout bristles. The proboscis is of mod- 

 erate size, rather strongly tapered to a roimded point 

 apically ; the dorsal ridge is conspicuous and high, the 

 whole compressed laterally, though only to a moderate 

 extent; the base is at most only slightly swollen and 

 bears only a few long hairs; at apex with stiff hairs. 

 The proboscis is directed downward. Palpus long, cy- 

 lindrical, with 5 quite stout, long, apical bristles and 

 shorter hairs ventrally and laterally. The anteima is 

 attached at the upper third of the head. The first two 

 segments are of equal length, each about twice as long 

 as wide. Third segment laterally compressed and at 

 most slightly wider than the second segment and as long 

 as the first two combined. The style of the third seg- 

 ment is about two-thirds as long as the segment and 

 bears a minute spine. There is a short microsegment 

 present. First and second segments with several, short, 

 stiff setae above and below; third segment with 3 or 

 4 long setae dorsally. 



Head, anterior aspect : The face below the antenna is 

 a sixth the head width, widening below to a fourth the 

 head width. Subepistomal area moderately large, 

 strongly oblique, slightly convex and bare. Face micro- 

 pubescent with only 2 or 3 hairs along the epistomal 

 margin. Bristles are restricted to the ventral gibbous 

 portion. They are all long and stout and occupy a tri- 

 angidar area with the upper elements directed straight 

 forward and curved, the lower bristles nearly straight 

 and directed obliquely downward. There are 2 long, 

 stout bristles on the sides of the subepistoma. Approxi- 

 mately 20 bristles present on the lower face. The front 

 is slightly divergent, the vertex slightly convergent. 

 Sides of front with 6 pairs of stout, short bristles, 

 among them 1 long bristle. Vertex moderately exca- 

 vated with nearly vertical sides ; ocellarium of moderate 

 size, bearing 2 pairs of minute bristles. Eye facets only 

 slightly enlarged. 



Thorax: The mesonotum and pleuron pollinose, the 

 pile of the mesonotum is very scanty, fine, appressed 

 and setate, more erect on the anterior margin and upon 

 the humerus which bears 1 or 2 slender bristles. There 

 is a double acrostical row of setae followed by a bare 

 stripe; the dorsocentral elements are differentiated at 

 the humeral level; these bristles are moderately long 

 at the notopleural level ; there are about 7 long, dorso- 

 lateral bristles beliind the transverse suture. Stout, 

 long, lateral bristles are present as follows: 1 posthu- 

 meral, 2 notopleural, 3 supraalar, 1 suprapostalar, 3 

 postalar and 1 pair of scutellar bristles. Scutellum 

 thick, with impressed rim; the disc is pollinose, with 

 some 8 pairs of fine, sharp, bristly hairs. Propleuron 

 with abundant, long, fine pile especially below. Prono- 



tum with fine pile and 3 pairs of long, stout bristles. 

 Upper and posterior mesopleuron with a few, fine, erect 

 hairs. Upper stemopleuron at most with 1 or 2 minute 

 hairs. Pt-eropleuron, however, dorsally with a patch of 

 12 or 14 weak bristles. Posthypopleuron with 3 long, 

 slender bristles and a patch spot of pubescence. Meta- 

 pleuron witli a wide band of about 20 slender, excep- 

 tionally long bristles. Metanotal slopes exceptionally 

 pilose, with an extensive patch of stiff pile. Lateral 

 and ventral metastemum with pile ; postmetacoxal area 

 membranous; posterior basalare with 4 or 5 bristles; 

 squama with a multiple fringe. Prostemum dis- 

 sociated. 



Legs: All the femora are stout; the anterior and 

 middle pairs are distinctly thickened, but the thickening 

 is distributed through the middle. All the femora are 

 characterized by their glassy, polished appearance with 

 pile almost absent ventrally and posteriorly. Hind 

 femur distinctly but gently dilated from the base to the 

 apex; it bears scanty, appressed pile above. Bristles 

 consist of 1 pair of long, exceptionally stout, dorsal, 

 subapical bristles and 1 equally stout bristle close but 

 proximal and on the same plane and sometimes a third 

 element dorsally just beyond the middle of the femur; 

 basal half with 2 more slender bristles. Hind tibia 

 quite stout, slightly attenuate basally, with 1 stout dor- 

 sal in the middle, 3 dorsolateral, 1 ventrolateral bristle 

 near the apex. The brush of setae is unusually dense, 

 long and extends to the base and also on to the first two 

 tarsal segments. Hind basitarsus unusually stout and 

 robust, its bristles spinous; it is fully three or more 

 times as long as the second segment. INIiddle femur 

 with a very long, stout, posteroapical bristle and a few, 

 fine hairs ventrally below towards the base. Middle 

 tibia with 2 short dorsal, 1 long, anterodorsal near the 

 apex and 3 or 4 ventral bristles besides before or at the 

 middle 2 basally stout, oblique, finely attenuate bristles. 

 "VVliole posterior surface and base dorsally with a dense 

 mat of appressed, long, coarse, silvery pile. Anterior 

 femur and tibia similar to the middle pair; the femur 

 lacks the posteroapical bristle, but has a dorsoapical 

 bristle. Anterior basitarsus short, excejitionally robust 

 and stout, not quite as long as the next two segments. 

 Tarsi end in well developed pulvilli, exceptionally ro- 

 bust stout claws which end more or less bhmtly and are 

 never sharp, and with the empodiiun short, greatly 

 swollen and wide laterally. 



"Wings: The wings are broad; strongly tinged with 

 brown and have purple reflections. Marginal cell 

 closed with a long stalk. The anterior branch of the 

 tliird vein ends above the wing apex; the second sub- 

 marginal cell is swollen anteriorly at the base. First 

 posterior cell narrowed in the middle by the second 

 posterior cell, the lower vein of the discal cell pulled 

 backward toward the base ; fourth posterior cell closed 

 with a long stalk. Anal cell closed with a long stalk, 

 second basal cell ends with two veins; alula large, am- 

 bient vein complete. 



Abdomen : The abdomen is distinctly shorter than the 

 wing and robust ; it is subcylindrical with nearly paral- 



