ROBBER FLIES OF THE WORLD 



505 



a tuft of 8 long, oblique, bristly hairs, the ventral mar- 

 gins of the swollen part also bear some long, stiff haii-s ; 

 the proboscis is directed obliquely downward. Palpus 

 stout with bristly pile, especially abimdant at the apex 

 and dorsally. The antemia is attached at the upper 

 fourth of the head and moderately elongate; the first 

 segment is a little longer than the second. The third 

 segment, with its microsegment is about ly^ times as 

 long as the combined length of the firet two segments. 

 It is subcylindrical or very slightly compressed lateral- 

 ly, attenuate apically to a very moderate extent and 

 bears a rather short, flattened microsegment which is a 

 little narrowed at its apex and carries in the middle of 

 the apex a distinct, short spine. 



Head, anterior aspect: The face below the antenna 

 is a fourth the head widtli and divergent at the 

 epistoma. Subepistomal area miusually deeply concave, 

 of moderate length and quite oblique. The face is 

 pubescent, the pubescence long, coarse and matted 

 laterally, and with numerous, fine, long hairs which are 

 slightly bristly in character. Down the middle half 

 of the face, beginning beneath the antenna, this pile 

 is rather long and across the epistomal margin are 3 

 paii-s of long, slender bristles with 3 or 4 pairs of ad- 

 ditional, slender bristles and other bristly hairs situated 

 in several rows along the sides of tlie subepistomal 

 margins. Front bare in the middle, quite short, with a 

 rather wide band of long, bristly pile along the eye 

 margins. Vertex but little excavated though the sides 

 are rather steep ; the ocellariiun is large but only mod- 

 erately high with steep sides, large ocelli and 3 pairs 

 of bristly haii-s across the middle, 1 pair of which is 

 accentuated and with 1 or 2 additional pairs between 

 the posterior ocelli. Posterior portion of vertex only a 

 little more deeply excavated; anterior eye facets but 

 little enlarged. 



Thorax : The thorax is minutely appressed pubescent 

 on many parts, which include the upper mesopleuron, 

 small portions of sternopleuron, middle hypopleuron, 

 the metapleuron, the lateral and medial portions of the 

 mesonotum, and on a prominent, converging stripe on 

 either side in the middle of the lateral part of the 

 mesonotum. The pronotum also is evei-ywhere pubes- 

 cent. The mesonotum is very steep and convex pos- 

 teriorly ; the anterior margin is vertical but not so hagh. 

 The pile of the mesonotum is rather dense but fine and 

 suberect for the most part but with considerable, short, 

 bristly pile medially. Acrostical elements are undif- 

 ferentiated, though there is a rather wide, medial band 

 of pale pile; on each side of this medial band is a rather 

 dense band of short, numerous dorsocentral elements 

 which become a little longer posteriorly and give way 

 on the posterior third of the mesonotimi to long, dense, 

 pale, slender bristles or bristly hairs. Humerus with 

 short, subappressed pile. The following complement 

 of long, stout, lateral bristles is present : 3 notopleural, 

 2 supraalar, 3 or 4 postalar. The postalar region has 

 additional bristly hairs. Margin of scutellum with 2 

 or 3 pairs of long, quite slender bristles and additional 

 long, bristly pile. Beginning on the outer edge of the 



convex, upper portion, the whole disc is covered with 

 long, erect, exceptionally dense, pale, bristly hairs. 

 Scutellum thick, convex, with distinct, impressed rim 

 and sharp basal crease; propleuron with abmidant, 

 long, stiff pile; the pronotum with 5 pairs of quite 

 slender bristles, but none on the posterolateral element, 

 which is separated from the posterior mesonotum by a 

 very deep crease or fissure. Upper border of the meso- 

 pleuron with abundant, stiff pile; anterior and upper 

 middle sternopleuron and the pteropleuron each witli 

 a tuft of fine hairs. Posthypopleuron with 8 or 10 long, 

 slender hairs. 



Metapleuron with 8 to 10 long, quite slender bris- 

 tles; lateral slopes of the metanotum pubescent only; 

 posterolateral metastemum and ventral metasternimi 

 with some long, fine pile; the latter is narrow and 

 chitinized; postmetacoxal area membranous; tegula 

 with setae ; basalare pubescent only. The middle ver- 

 tical band of the metapleuron may contain as many as 

 30 elements. 



Legs: The anterior and hind femora are distinctly 

 swollen and heavier than usual but the middle femur is 

 very greatly swollen and oval and the swelling is as 

 much ventral as dorsal. Dorsal pile dense but rather 

 fine, long, and appressed. The following complement 

 of bristles, wliich are mostly stout, and rather short, 

 present in the type of genus : Hind femur with 3 dorso- 

 lateral, 2 of them on the outer half, and 1 additional 

 more nearly dorsal element, and 1 somewhat weaker 

 dorsomedial element, all of which are subapical; apex 

 with 1 moderately stout, dorsomedial bristle. Also 

 there are 5 stout, pale, attenuate, ventrolateral bristles 

 followed by 4 ventrolateral, subapical, almost spinelike, 

 rather blunt, black bristles, of which there are 2 ventro- 

 medial coimterparts. In addition there are about 10 

 stout, ventromedial bristles extending to the base, with 

 2 or 3 more ventral, basal bristles. Hind tibia with 4 or 

 5 doi"Somedial and 3 or 4 dorsolateral bristles. The 

 bristles at the apex are very strong and include 4 ven- 

 tral, 1 ventral subapical, and 2 weak, subdorsal elements 

 which are lateral and medial. Middle femur with 2 

 stout, pale, posterodorsal subapical bristles and 2 stout, 

 short, pale anteroventral bristles in the middle, 3 slender 

 anterior elements in the middle, and with characteris- 

 tically on the ventral margin on the outer third a row 

 of 6 short, black, subtuberculate, very stout spines. 

 Middle tibia with a few long, bristly hairs posteriorly 

 and on the outer third of the anteroventral margin with 

 a row of 6 short, black spines together with an addi- 

 tional, still more stout element at the apex. The cor- 

 responding posteromedial margin has 5 such robust 

 spines. 



Anterior femur with a strong, black subapical bris- 

 tle anteroventrally and with long bristly hairs ventrally. 

 Anterior tibia with at least 4 anterodorsal and 1 or 2 

 apical posteroventral bristles but otherwise with only 

 coarse, appressed pile. The apex on the ventral half 

 has 7 or 8 spinelike bristles. Anterior basitarsus short 

 and stout, as long as the next two segments ; the middle 



