4SILINAB 



ROBBER FLIES OF THE WORLD 



537 



middle of the face. The eye is of moderate length, con- 

 vex anteriorly and narrowed below, plane on the pos- 

 terior profile on the upper half ; it is strongly recessive 

 anteroventrally and also plane on the lower two-fifths 

 of the eye. The occiput is moderately thick, with the 

 pile of the occiput quite dense ventrally and rather 

 long; slender bristles begin below the middle of the 

 eye and are straight and only moderately long. The 

 dorsal bristles of the same length are somewhat more 

 stout and also straight. There are at least 25 paire on 

 each side. The proboscis is of only moderate length and 

 thickness, a little swollen basally from the dorsal as- 

 pect, the apex is bluntly rounded, with sliort, bristly 

 pile above, below and laterally. The base has niuner- 

 ous, fine, long hairs ventrally and laterally; proboscis 

 directed obliquely forward. Palpus small, slender, cy- 

 lindrical with fine pile at the apex and ventrally and 

 laterally. The antenna is attached at the upper third 

 of the head and moderately long; the first segment is 

 11/^ times as long as the second. The third segment is 

 a little compressed laterally, 114 times as long as 

 the first two segments combined and rather strongly 

 tapered from near the base; it bears a short, distinct, 

 stout microsegment followed by a second, equally stout, 

 very slightly tapered microsegment which is three times 

 as long as the first microsegment and carries a distinct, 

 central, apical spine. 



Head, anterior aspect: The face below the antenna 

 is a fourth the head width and divergent at the 

 epistoma. Subepistomal area oblique, large, very 

 slightly concave and pubescent. The face is densely, 

 minutely pubescent or pollinose without pile on the 

 upper three-fourths or lateral margins. Above the 

 epistoma and encircling the lateral margins to a point 

 equal the bottom of the eye, is a double or treble row 

 of long, but very slender bristles, and above these 

 bristles in the middle of the face are a few, excep- 

 tionally fine, shorter hairs. Front pollinose, with a 

 wide, oval, lateral fascia of slender bristles containing 

 approximately 15 elements. Vertex but little excavated ; 

 the ocellarium rather large, moderately high with 

 vertical sides, large ocelli and bearing in front of each 

 posterior ocellus a short, slender bristle; also there is 

 a pair of bristles between these ocelli and a close-set 

 tuft of 5 pairs behind the ocelli. Anterior eye facets 

 slightly enlarged. 



Thorax: The thorax is pollinose; the pile of the 

 mesonotum is moderately abundant but quite bristly in 

 character and also moderately long and suberect. There 

 is an irregular band of acrostical bristles of the same 

 length which are differentiated only anteriorly. Dorso- 

 central elements are differentiated opposite the suture 

 but they become quite long and stout posteriorly with 

 4 such bristles on each side. The humeri have bristly 

 pile. In the type of genus the following complement 

 of long, rather stout bristles is present : 2 notopleural, 

 3 supraalar, 1 suprapostalar, 3 postalar, and 2 pairs 

 of scutellar bristles. All the long bristles are pale ; the 

 bristly hairs are black, except on the pleuron. Scu- 



tellum thick, convex with impressed rim, pollinose, with 

 numerous, long, bristly discal hairs. The base is fused 

 in the middle. Propleuron with a long, dense, bristly 

 pile; the pronotum and the posterolateral pronotum 

 with several slender bristles. Upper mesopleuron, 

 upper middle and anterior sternopleuron, pteropleuron 

 and the posthypopleui'on with long, fine pile. Meta- 

 pleuron with at least 4 long, stout bristles and con- 

 siderable, additional, bristly hairs. Lateral slopes of 

 the metanotum with a large patch of bristly pile. 

 Lateral and ventral metasternmn with abundant, long 

 pile; postmetacoxal area membranous; tegula with 

 minute setae ; posterior basalare with a ventral tuft of 

 6 or 7 bristly hairs; anterior basalare pubescent only. 

 Squama with a multiple fringe. 



Legs: The hind femur is relatively slender, especially 

 towards the base, but slightly thickened distally, and 

 is one-third longer than the middle femur. Anterior 

 and middle femora stout without being swollen. Dorsal 

 pile of the hind femur, its anterior, ventral, and medial 

 pile, and the dorsal pile of the remaining femora all 

 fine, appressed and setate. In the type of genus the 

 following complement of stout, long, pale bristles pres- 

 ent: 4 lateral, 4 ventrolateral, all crowded close to the 

 apex and quite small, and at the outer fifth 1 stout, 

 dorsolateral bristle, 2 similar dorsomedial, 3 long, 

 medial bristles; and on these tibiae 6 dorsomedial, 3 

 dorsolateral, 2 ventrolateral. Tlie middle femur has 



2 long, stout anterior, 2 or 3 anteroventral on the basal 

 half, and a conspicuous row of 8 ventral and a row of 

 11 or 12 posterior bristles, some of them double and all 

 rather short. Middle tibia with 2 anterodorsal, 3 pos- 

 terodorsal, 3 posterior and 3 posteroventral, and 3 stout 

 anteroventral bristles. Anterior femur with 2 or 3 

 short, posterior bristles and 4 ventral bristles, of which 



3 are basal; its tibia has 1 long, strong, basal antero- 

 dorsal, 3 posterodorsal, 2 quite long, posteroventral near 

 the middle, and 4 or 5 short, slender posterior bristles. 

 The posterior tarsi are comparatively long, the anterior 

 tarsi shorter; anterior basitarsus as long as the next 

 two segments. Posterior basitarsus as long as the next 

 three segments. Tarsi end in a slender, sharp claw 

 curved at the apex, long spatulate pulvilli, and a rather 

 slender empodium only about half as long as the claw. 



Wings: Marginal cell of normal width and closed 

 with a long stallc. Subcostal cell rather narrow. The 

 anterior branch of third vein ends distinctly above the 

 wing apex ; the posterior branch ends behind the apex 

 by twice that distance. Fourth posterior cell closed 

 with an unusually long stalk ; this cell is long, strongly 

 convex anteriorly, a little convex distally and nearly 

 straight behind. Second basal cell ends in two veins. 

 Anal cell closed with a rather long stalk; the axillary 

 lobe is long; the anal vein concave posteriorly. Alula 

 large, the ambient vein complete though reduced on the 

 axillary lobe. 



Abdomen : The abdomen is considerably longer than 

 the wings ; at the base it is distinctly more narrow than 

 the mesonotum, cylindroid and rather strongly tapered. 



