ROBBER FLIES OF THE WORLD 



517 



prominent. The occiput is -well developed sublaterally 

 and the lower sixth of the eye is recessive anteroven- 

 trally. Lower half of occiput with rather dense, fine 

 hairs and at the bottom of the eye a tuft of still longer, 

 bristly hairs. Bristles begin at the middle of the head 

 and are curved downward; there are 7 dorsal bristles 

 which are most stout and straight in partly doubled 

 row. Proboscis stout and a little swollen basally. The 

 apex bears bristly hairs and a preapical crease. The 

 swollen base ventrally has numerous, long, bristly hairs. 

 Palpus cylindrical with fine, bristly haire. The antenna 

 is attached at the upper third of the head, the first seg- 

 ment is 2y2 times as long as wide and a little longer than 

 the second segment. Both bear numerous, long, fine 

 setae dorsally and niunerous, slender bristles and setae 

 below. The third segment is as long as the first two, 

 widest near the base and uniformly tapered above and 

 below to the narrow apex, which bears a short, distinct 

 microsegment and a stout bristle-tipped style approxi- 

 mately as long as the third segment. 



Head, anterior aspect: The width of the head is 

 11^ times the height. The face below the antenna is 

 about a sixth the width of the head and strongly 

 widened below. The whole surface is densely, appressed 

 micropubescent, continued over the subepistoma. The 

 upper half of the face has no pile, the lower half has 

 a large triangle of long bristles ; upper part of triangle 

 with 5 or 6 moderately stout, black bristles and on each 

 side 6 quite small, black bristles. Middle and lower 

 portion of the mystax consists of 10 exceptionally stout, 

 pale bristles and on each side of the subepistoma 3 or 

 4 long bristles and a few bristly hairs. Front small, 

 pollinose, slightly wider than the upper face, with a 

 subocular row of 4 moderately long, stout bristles and 

 2 setae and dorsally nearer the eye a row of 3 setae. 

 Vertex rather strongly narrowed but little excavated, 

 with slanting sides. The ocellarium is large but low 

 and bears 1 or 2 pairs of short bristles or long setae be- 

 tween the ocelli and 2 pairs behind. 



Thorax : The thorax is rather high, the mesonotiun is 

 comparatively high and convex. Surface pollinose with 

 scanty setae and a few fine hairs posteriorly above the 

 wing. There is a double row of acrostical setae ex- 

 panded to 4 rows anteriorly; dorsocentral bristles be- 

 gin behind the suture and consist of 4 or 5 short, slender 

 elements and 2 long, stout bristles. Lateral bristles 

 long and stout. There are 2 notopleural bristles, 1 su- 

 praalar bristle with a weaker element beyond, some- 

 times absent ; and a long bristle above the postalar cal- 

 losity, besides 1 or sometimes 2 on the postalar callosity. 

 Scutellar margin without bristles. The margin and the 

 disc bear a few, quite minute, very finely attenuate 

 setae. The scutellum is moderately thick, pollinose with 

 deeplj' impressed rim. The metanotal callosity creased 

 belimd and bearing a patch of bristly pile. Pleuron 

 densely pollinose with dorsally on the mesopleuron 

 only a few short, appressed, fine hairs in which are 

 mixed 3 long but very fme hairs. Metapleuron with 

 a vertical row, partly doubled, of 7 or 8 long, slender 



bristles and some long, fine hairs. There is a vertical 

 row of similar fine hairs on the hypopleuron and scat- 

 tered hairs dorsally on the sternopleuron. Postmeta- 

 coxal area membranous; presternum fully dissociated. 



Legs: All the femora are stout, the hind pair is grad- 

 ually and slightly swollen from the base towards the 

 apex ; the anterior femur is swollen chiefly on the basal 

 half and the middle femur swollen throughout its 

 length. The legs bear dense, fine appressed hairs that 

 are continued on the ventral surfaces and absent or re- 

 duced only narrowly on the medial surface of the 

 middle femur and posterior surface of the anterior 

 femur. Bristles are stout and sharp. The hind femur 

 bears 3 dorsolateral bristles, 2 of them lie on the outer 

 half and there is an additional bristle laterally at the 

 apex and 6 ventrolateral bristles, the last element also 

 at the apex. This femur has a prominent apical and 

 also a subapical dorsomedial bristle and 6 ventral 

 bristles, besides 7 medial bristles. Posterior tibia com- 

 paratively slender and quite long, a little swollen dis- 

 tally; it bears 3 prominent dorsolateral bristles, 1 of 

 which is at the base and matched by a dorsomedial 

 bristle ; there are 2 prominent ventrolateral bristles on 

 the outer half but no ventral elements. Hind basitarsus 

 stout, as long as the next tlu-ee segments. Middle femur 

 with a very stout, anterior bristle at the basal and 

 apical third, 4 anteroventral bristles and ventrally on 

 the basal half 1 long and 9 short, spikelike bristles. 

 Middle tibia with a single anterodorsal bristle on the 

 outer third, a smaller posterodorsal bristle in the 

 middle, 1 posterior distal bristle, a longer, posterovon- 

 tral bristle, and 2 or 3 prominent, stout, long, ventral 

 bristles. 



Anterior femur with 1 moderately long, anterior 

 apical bristle and beside it 1 short bristle ; the small ele- 

 ment is sometimes lacking. Anterior tibia rather short. 

 It bears a stout bristle anterodorsally near the base, a 

 smaller one posterodorsally at the outer third, and it 

 has 3 long, stout, pale, ventrolateral bristles and a few 

 long, ventral bristly hairs. Anterior basitarsus com- 

 paratively short, as long as the next 2 segments. Claws 

 stout, moderately sharp, curved chiefly at the apex; 

 pulvillus long, wide; empodium long and bladelike. 



Wings: The wings are brownish hyaline; marginal 

 cell closed, narrowed at apex, with a long stalk; it is 

 widened in the middle and the subcostal cell is narrow 

 through the middle. The third vein forks opposite the 

 end of the discal cell; the second submarginal cell is 

 narrow at the base, almost entirely widened anteriorly, 

 with upper and lower branches of the third vein mostly 

 straight. Upper branch ends slightly above apex, 

 lower branch curves rather far backward. Fourth pos- 

 terior cell closed with a long stalk. Anal cell closed and 

 stalked, posterior crossvein absent. Alula large; am- 

 bient vein complete. Wliole wing villose except parts 

 of basal and central cells. 



Abdomen : The abdomen is subcylindrical and polli- 

 nose, with scanty, fine, appressed pile dorsally; the 

 lateral pile is more or less appressed and scarcely 



