DASTPOGONINAB 



ROBBER FLIES OF THE WORLD 



265 



along the middle and lower portion ; the middle pile is 

 somewhat matted or appressed and directed con- 

 spicuously downward ; the dorsal pile is fine and short 

 anteriorly, longer posteriorly and medially; bristles 

 are absent. The proboscis extends as far as the antenna 

 and is directed forward; it is attenuate with bluntly 

 rounded apex and a few stiff, apical hairs. Palpus of 

 two segments, the first excavated, the second longer, 

 cylindrical, attached to one side of the apex of the first 

 segment; the end segment is tapered with blunt apex 

 and bears bristly pile on all sides as well as the apex 

 and is not porate. The antenna is attached at the 

 middle of the head and is moderately elongate; the 

 first and second segments are nearly equal in length 

 and longer than high. The third segment is, with 

 microsegments combined, a little more than iy 2 times 

 the length of the first two segments ; this segment is of 

 nearly uniform thickness with annulate base fully as 

 wide as the middle of the segment; at the end it bears 

 two distinct microsegments, the first quite short, the 

 second long, stout, sharply attenuate with bristle at 

 tip. The third segment is obliquely truncate at the 

 end which results in the microsegments being directed 

 downward. The first segment bears several long, 

 bristly hairs on all sides except medially ; second seg- 

 ment with 1 long, stout bristle ventrally, 3 long bristly 

 hairs, and 6 or more bristly setae. 



Head, anterior aspect: The face below the antenna 

 is about one-fourth of the head width. The subepis- 

 tomal area is large and oblique. The face is coarsely 

 micropubescent with the short cheeks bare. Face pile 

 is composed of 10 to 12 bristly, white hairs on each side, 

 and below near the subepistoma is a lateral patch of 

 6 or 7 more closely set similar hairs. There a trans- 

 verse row of 5 stout, black bristles crosses the lowest 

 part of the face and extends out to the apex of the 

 proboscis; above these is a curved row of 5 similar 

 bristles, a little less stout and not as long. The front is 

 wide, flat, pollinose, and almost without pile or bristles ; 

 on each side near the anterior ocellus are 2 slender, 

 stiff, black hairs. The vertex is deeply excavated, 

 chiefly because of the dorsal extension of the eye; the 

 ocellarium is large, high and conspicuous, with vertical 

 sides, it bears 3 pairs of long, slender, bristly hairs 

 in the middle. The anterior ocellus exceptionally 

 enlarged. Anterior eye facets strongly enlarged. 



Thorax: The mesonotum and pleuron are covered 

 with fine micropubescence. Mesonotal pile is scanty, 

 coarse, bristly and flat appressed; there is a distinct 

 acrostical row of short, appressed pile with a wide, 

 bare space on each side; dorsocentral elements are 

 not differentiated from the mediohumeral pile and not 

 in evidence posteriorly except for a single, stout bristle 

 on each side in front of the scutellum. The lateral 

 bristles are stout, of medium length, and black; they 

 consist of 2 especially stout notopleural, 2 weaker post- 

 supraalar, 1 postalar, and 1 pair of marginal bristles 

 on the scutellum. The scutellum is quite thick, con- 

 vex, with a deep basal crease, pollinose, and apilose. 



Propleuron with scattered, long, fine pile; pronotum 

 with similar pile, exceptionally long, and bristles 

 absent ; lateral pronotum with long, fine pile only. On 

 the mesopleuron the pile is restricted to the posterior 

 half; pteropleuron and hypopleuron apilose; meta- 

 pleuron exceptionally bullose and swollen from its pos- 

 terior aspect and with a wide band of numerous, long, 

 coarse hairs. Lateral slopes of the metanotum are 

 micropubescent only; tegida with a few minute setae. 

 The anterior basalare has a distinct, long, narrow 

 ventral, chitinized wedge extending down between 

 the mesopleuron and pteropleuron. Lateral and ven- 

 tral metasternum with pile; postmetacoxal area 

 membranous. 



Legs: The hind femur and tibia are elongate; this 

 femur is slightly wider on the outer half, and gently 

 tapered towards the base; the tibia is slender, swollen 

 only quite close to the apex, and with a brush of ven- 

 tral setae only on the outer fifth. The coxae are pubes- 

 cent, the remainder of the legs shining. The femora 

 bear ventrally scanty, scattered pile which is a little 

 more abundant and subappressed on the dorsal half. 

 The hind femur has no bristles. The hind tibia bears 

 4 dorsomedial and 4 dorsolateral short, moderately 

 stout, black bristles, in each group of which 3 of the 

 bristles are on the basal half; it also bears 2 ventro- 

 lateral bristles. Middle femur with 1 well developed 

 posterodorsal, 5 posteroventral, and 3 anteroventral 

 bristles. Anterior femur with 1 yellowish postero- 

 dorsal subapical bristle, its tibia with 8 minute, short, 

 anterodorsal, 6 longer posterodorsal, 5 still longer 

 posteroventral bristles. The apex of the anterior tibia 

 bears a basally stout, bluntly pointed, slightly curved, 

 but not twisted spine which arises from a low pro- 

 tuberance. The basitarsus has a slightly raised patch 

 of denticles. The anterior tarsus is exceptionally long, 

 nearly or quite twice as long as the tibia; other tarsi 

 not unusually lengthened. Claws sharp ; pulvilli spatu- 

 late and well developed ; empodium long, bladelike and 

 swollen at the immediate base. 



Wings: The wings are tinged with brown and with 

 hyaline streaks in the first basal and marginal cells. 

 Marginal cell widely open. The anterior branch of 

 the third vein arises barely beyond the end of the discal 

 cell; the anterior crossvein is rectangtdar and enters 

 the discal cell beyond the middle ; lower end vein of the 

 discal cell is twice as long as the upper end vein and 

 drawn obliquely backward. The first posterior cell 

 is widely open ; fourth posterior cell open but greatly 

 nan-owed; anal cell narrowly open. The second basal 

 cell ends in two veins ; alula twice as wide as the costal 

 cell ; ambient vein complete. 



Abdomen: The abdomen is robust, cylindroid, with 

 parallel sides but not as wide as the mesonotum. The 

 tergites tend to be a little flattened across the middle. 

 Males with seven tergites, the seventh is three-fifths 

 as long as the sixth ; the sixth is shorter than the fifth. 

 Pile of abdomen is very fine, short and scanty; the 

 posterior margins have a whitish pollinose fascia which 

 expands laterally into large triangles. The first two 



