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UNITED STATES NATIONAL MUSEUM BULLETIN 2 24 



and the front narrow in the same proportion, so that 

 the vertex is quite narrow. Face without pile and 

 bristles are restricted to an epistomal row and are 

 stout. "Wings tinged with yellow, brown or blackish 

 in color. Legs elongate, scutellum without bristles. 

 Length 12 to 30 mm. 



Head, lateral aspect : Face greatly reduced in height 

 and at the base of the antenna nearly plane with the 

 eye. It is gently and gradually produced below but 

 is never extensive. The epistoma is exceptionally 

 large and oblique and concave to a varying extent. Oc- 

 ciput only moderately developed, almost concave or 

 depressed at the eye margin and sloping gradually in- 

 ward. Ventrally the occiput bears only a few, coarse 

 or fine, scattered hairs; weak bristles begin along the 

 middle and become much stouter dorsally. They are 

 usually present in a row. Proboscis stout, especially 

 at the base and gently tapered or attenuate towards 

 the apex which is bluntly rounded. There is a medial, 

 dorsal ridge generally more extensive towards the base 

 and the apex bears fine pile above and below. Palpus 

 clearly composed of two segments, the first segment 

 quite short, more or less fused at least basally and 

 apparently cylindrical apically. Second segment cy- 

 lindrical, the immediate apex a little narrowed and 

 bearing a few, slender hairs or bristles. The antenna is 

 attached near the middle of the head but generally 

 is only moderately long; it is approximately as long 

 as the head if microsegment is included. The first 

 two segments are equal in length and at least iy 2 times 

 as long as wide or a little longer. Dorsally these seg- 

 ments bear long setae and ventrolaterally each has 

 several slender bristles. Third segment as long or 

 slightly longer than the combined length of the first 

 two segments, with several dorsal bristles and with 

 two microsegment s, the first of which may be quite 

 short, the second considerably longer, attenuate, with 

 apical spine. The third segment is a little widened, 

 especially along the middle on its ventral aspect, so 

 that it may appear to be long oval in shape. 



Head, anterior aspect: The head is very peculiar 

 from the anterior view ; it is more than IV2 times as wide 

 as high. The face below the antenna is wide, but very 

 much wider below, being conspicuously widened and 

 again the front is narrowed at the same progressive 

 rate, so that the vertex is quite narrow and the entire 

 front vertex and face appear triangular. Another 

 peculiarity consists in the remarkably deep, conspicu- 

 ous pockets on each side of the epistoma, which in some 

 species are continued through to the posterior side. 

 These pockets represent the points of invagination of 

 the anterior arms of the tentorium. Face densely pol- 

 linose, without pile but with a single row of 6 to 10 

 quite long, stout, curved bristles, which extend forward 

 nearly as far as the proboscis. Front as described, 

 strongly convergent, flat and pollinose and without 

 pile or bristles in all species. Ocellarium large but 

 quite low, with vertical sides and large ocelli and with 

 a pair of slender bristles arising behind the ocelli, and 

 sometimes a pair of small, bristly hairs between the 



ocelli, or also a pair of bristles between the ocelli. 

 Vertex only moderately excavated. 



Thorax: The mesonotum is moderately high and 

 arched, pollinose with scanty, bristly or long, setate pile 

 and prominent, long, stout bristles. There is a wide, 

 bare band medially containing acrostical setae and 

 dorsocentral bristles are often well developed in front 

 of the suture and more prominent behind. The comple- 

 ment of bristles consists of 3 or 4 stout, anterior humeral 

 bristles, 3 notopleural, 1 supraalar, 2 on the postalar 

 callosity, and 1 or 2 pairs of stout, conspicuous bristles 

 on the scutellum or none at all. Metanotal callosity 

 pollinose only. Pleuron pollinose; the pronotum has 

 weak bristles but none laterally. Metapleuron with an 

 oblique row of 5 or 6 bristles and other long, bristly 

 hairs. Postmetacoxal area membranous; only the 

 lateral metasternum bears pile; prosternum fully 

 dissociated. 



Legs : The legs are unusually long, especially the hind 

 pair, and they are rather densely appressed setate, with 

 the bristles on the tibia rather short but stout and very 

 few on the femora. Hind femur with 1 ventrolateral 

 bristle at the apex, 1 dorsomedial bristle subapically. 

 Anterior and middle femora each with a stout, postero- 

 dorsal, subapical bristle and a smaller, anteroventral, 

 subapical bristle. Middle femur with a long, basal, 

 ventral bristle. Anterior and middle trochanters with 

 very long, stout, curved bristles at the apex. Posterior 

 tibia with 6 dorsolateral, 5 dorsomedial, and 4 ventro- 

 lateral bristles. Apex with 8 bristles. Hind basitarsus 

 as long as the next 4 segments. Anterior tibia with 4 

 anterodorsal, 6 smaller posterodorsal, 6 posteroventral, 

 and 2 extraordinarily long ventral bristles on the outer 

 half. The last 2 of the anterodorsal bristles are nearly 

 as long as the ventral bristles. Anterior tibia with 3 

 basal, weak, anterodorsal, 6 equally small posterodorsal, 

 3 small and 2 long posteroventral bristles. Apex with- 

 out spine. Claws long, sharp, bent at apex; pulvilli 

 large ; the empodiiun bladelike. 



Wings : The marginal cell is widely open, the anterior 

 branch of the third vein ends at wing apex, and the 

 second submarginal cell at its base is expanded only 

 anteriorly. First posterior cell widely open, the fourth 

 distinctly narrowed. Anal cell closed and stalked, or 

 closed in the margin. Alula moderately wide ; ambient 

 vein complete; whole wing villose and the whole wing 

 characteristically tinged with brown or yellow or both. 



Abdomen : The abdomen is elongate, rather slender, 

 subcylindrical and in many species very slightly clavate 

 so that the fifth to sixth segments may be slightly 

 wider. Surface rather densely covered with fine, ap- 

 pressed setae and at most a few, scattered hairs laterally 

 along the sides of the first and second segments. Sides 

 of first segment with 6 or 7 bristles which are rather 

 stout and some bristly hairs. Posteriorly the second 

 segment often has 2 or 3 moderately stout, lateral 

 bristles but they may be absent. Males with eight 

 tergites but the eighth quite short. Females with 

 eight segments, the last being half as long or longer 

 than the seventh. Male terminalia rotate at least a 



