ROBBER FLIES OF THE WORLD 



571 



than the remainder and, indeed, quite stout. The 

 bristles on the lower, medial portions are pale and 

 they are slender ; black and pale bristles are continued 

 laterally down the sides of the subepistoma. The front 

 is bare in the middle, micropubescent laterally, and 

 bears 4 slender, bristly hairs laterally and i slender, 

 black bristles. Front divergent in the middle, con- 

 vergent at the apex; the vertex deeply excavated, the 

 ocellariiun large, but low, and with 2 pairs of slender 

 bristles across the middle in a circular row, 2 slightly 

 longer bristles between the posterior ocelli and 2 

 equally long elements behind the ocelli. Anterior eye 

 facets rather strongly enlarged. 



Thorax: The thorax is entirely micropubescent, as- 

 suming more the character of pollen medially upon the 

 mesonotum. The pile of the mesonotum is moderately 

 abundant and composed of stout, short, slightly ap- 

 pressed bristles. There are no differentiated acrosti- 

 cal elements although near the midline there is on 

 either side a slightly irregular row, narrowly sepa- 

 rated, of short bristles merging into similar bristles 

 laterally. Dorsocentral elements are differentiated a 

 short distance before the suture and immediately be- 

 come very long and stout with 6 or 7 pairs. Humerus 

 with a few, fine, long hairs. The lateral bristles are 

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

 supraalar, 1 suprapostalar, 1 or 2 postalar and 1 or 2 

 pairs of scutellar bristles. The scutellum is only mod- 

 erately thick, convex, with distinctly impressed rim ; it 

 is densely pubescent, with numerous, rather fine, long 

 erect hairs; propleuron with abundant, long, fine pile 

 laterally and ventrally ; the pronotum has 2 or 3 pairs 

 of rather stout bristles. Upper mesopleuron with a 

 few, fine, long hairs, 2 slender bristles and several long 

 hairs on the dorsal middle portion of the sternopleu- 

 ron, a few fine hairs anteriorly and 1 or 2 slender, 

 bristly hairs posteriorly on the mesopleuron, 3 or 4 

 fine hairs on the pteropleuron. There are on the post- 

 hypopleuron a quite stout, long bristle and several 

 slender bristles, and on the metapleuron 7 long, stout 

 bristles in a vertical row. The lateral metanotal slopes 

 have numerous, bristly hairs. The lateral metasternum 

 has a few, long hairs, the ventral metasternum is long 

 pilose; postmetacoxal area pubescent but membranous ; 

 tegula without setae; posterior basalare with 1 or 2 

 minute hairs; squama with a multiple fringe. 



Legs: All the femora are stout, the anterior and 

 middle pairs thickened basally, especially on the fore- 

 legs. The dorsal and lateral pile is flat appressed and 

 setate. On the hind femur the bristles consist of 3 

 lateral and 2 dorsolateral on the apical third, 6 ventro- 

 lateral, 1 ventromedial beyond the middle and 3 or 4 

 ventral on the basal half ; the trochanters have a stout, 

 medial bristle and 1 to 3 ventral elements; the poste- 

 rior coxa has 2 lateral bristles and 3 weak, anteroventral 

 bristles. The hind tibia has 1 dorsomedial just before 

 the middle, 3 dorsolateral, 1 at the base, the middle, and 

 the outer fourth and 2 ventrolateral bristles, on the outer 

 half; a brush of setae is present only near the apex. 

 The middle femur bears 2 quite stout, long anterior bris- 



tles at basal and distal third and 6 long, slender, pale 

 bristly hairs ventrally. The middle tibia has 3 dorsal 

 bristles beginning near the middle, 2 anterodorsal on 

 the outer half, 3 posterior, 1 or 2 posteroventral, and 2 

 anteroventral bristles. Anterior femur bears 4 rather 

 prominent bristles dorsally on the outer half and 7 

 long, slender, bristly hairs ventrally towards the base; 

 anterior tibia slightly bent outward in the middle with 



1 dorsal at the base, 3 posterodorsal on the outer half, 

 3 quite long, basally stout, posteroventral bristles, be- 

 ginning just before the middle. The anterior basitarsus 

 is a little longer than the next 2 segments. All tarsi 

 end in long, sharp, pointed claws, strongly bent at the 

 apex; large, spatulate pulvilli; the empodium is long 

 and distinctly bladelike. 



Wings: The marginal cell closed, the subcostal cell 

 comparatively narrow, the wing not expanded anteri- 

 orly but gently rippled; the anterior branch of the 

 third vein ends a short distance before the wing apex, 

 the posterior branch ends an equally short distance 

 behind; the second submarginal cell is slightly nar- 

 rowed beyond the middle. The first posterior cell is 

 somewhat narrowed, opposite the basal portion of the 

 second submarginal cell; the second posterior cell 

 widely open, only slightly swollen at the base anteriorly. 

 Fourth posterior cell closed and stalked and gently 

 convex on all sides; the lower end vein of the discal 

 cell is pulled strongly back towards the base of the 

 wing; the second basal cell ends in two veins; alula 

 large, the ambient vein complete; the wing is avillose 

 in the first two basal cells and the base of the discal 

 cell and the anterobasal portion of the first posterior 

 cell. 



Abdomen : The abdomen is slightly tapered and more 

 or less subcylindrical. Sides of the first tergite only 

 moderately protuberant. The pile of the abdomen is 

 scanty, appressed and setate ; the first two tergites have 



2 or 3 stout bristles, the lateral postmargins of the 

 second and third tergites bear 4 rather strong bristles, 

 the remaining tergites have somewhat weaker bristles 

 in the male but sometimes with stout bristles. On the 

 second to the fifth tergites in the female the bristles are 

 sometimes reduced to 1 or 2 on each side or sometimes 

 with only very weak bristles present on all except the 

 first tergite. First sternite without pile; remaining 

 sternites with fine, long hairs which may be replaced 

 in some cases on the last 4 sternites by short, appressed 

 setae. Seven tergites present dorsally in the male, the 

 seventh is an eighth the length of the sixth dorsally 

 but more than a third as long laterally, and laterally 

 there is a minute, liplike trace of the eighth tergite. 

 The eighth sternite is extremely short but without any 

 posterior, liplike extension. Female with seven tergites, 

 the seventh about as long as the sixth. The male termi- 

 nalia is moderately large and not rotate. The superior 

 forceps apt to be elongate, apically pointed, directed 

 upward and slightly curved inward apically. The fe- 

 male terminalia is li/| to 2 times as long as the seventh 

 tergite and strongly compressed laterally, without 

 spines or bristles. 



