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UNITED STATES NATIONAL MUSEUM BULLETIN 224 



in this row lying beyond. Claws moderately stout, 

 strongly bent at the apex and sharp. Pulvillus long, 

 tlie empodium slender and a little thickened at the base. 



Wings : The wings are brownish hyaline with dense 

 villi, except on the basal cells. Marginal cell is closed, 

 rather wide apically, with a comparatively short stalk. 

 The second submargmal cell basally is widened only 

 in front of the third vein and the posterior branch of 

 the tliird vein at the middle has a very strong bend 

 or undulation. Upper portion of the anterior and inter- 

 calary veins quite short, the long medial crossvein 

 parallels the wing margin. Posterior crossvein absent, 

 alula large, ambient vein complete. 



Abdomen : The abodmen is comparatively short, sub- 

 cylindrical above, flattened below and not as wide as 

 the mesonotum. The surface bears fine, scattered, ap- 

 pressed setae and the subapical margin of the tergites 

 have conspicuous fringes of long, pale, quite slender 

 bristles or bristly hairs. Sides of first tergite with at 

 least 4 long, stout bristles and other long, bristly hairs. 

 First segment short, second long, the remaining seg- 

 ments progressively reduced and the eighth male tergite 

 and sternite quite short, almost linear. Male terminalia 

 rather conspicuous and elongate, not rotate, the su- 

 perior forceps are not strongly divergent, and the proc- 

 tiger small and oblique, and compressed laterally with 

 a fringe of bristly setae. The forceps have a strong, 

 long, hooklike prong or process posteriorly, another 

 dorsally near the middle and both cross the midline. 

 Gonopod prominent. Hypandrium well developed 

 laterally but greatly reduced ventrally so that the penis 

 guides are fully exposed below and arched forward 

 and upward. 



Distribution : Oriental : Strophipogon hromleyi Hull 

 (1958). 



Genus Negasilus Curran 



Figures 386, 766, 1477, 1486, 2238, 2245, 2392, 2397 



Negasilus Ciirran, Families and genera of Noi'th American Dip- 

 tera, pp. 183, 184, 1934. Tyi)e of genus: Negasilus helU 

 Curran, 1934, by original designation. 



Small flies without conspicuous bristles on the sides 

 of the tergites, except the first, where they are prom- 

 inent. The face is almost as short as in Cerdistus Loew 

 and Negasilus appears to find its true relationship with 

 that genus. The stemites have only scanty, short, fine, 

 appressed setae with no long hairs or bristles present. 

 From related genera and from Asilus Linne it differs 

 in the absence of scutellar bristles. The ovipositor 

 tends to be cylmdrical and conical, compressed only on 

 the ninth segment. Length 12 to 15 mm. 



Head, lateral aspect : The head is of medium length, 

 the face quite short on the upper half, with on the 

 lower portion a short, inconspicuous gibbosity which is 

 rendered more prominent because of the recession of 

 the eye. The occiput is short, but uniformly developed ; 

 the ventral fourth of the eye has a pronounced, angular, 

 anterior recession. The proboscis is short and robust 



and scarcely or not at all extended beyond the face. 

 The apex is bluntly rounded; the base below has nu- 

 merous, slender, bristly hairs. The pile of the occiput 

 is fine and dense on the lower third, with a conspicuous, 

 long, dense tuft on each side • behind the proboscis. 

 Bristles begin at the middle of the head; the lower 

 elements are turned down, the upper elements are stout 

 and continued along the lateral slopes of the postver- 

 tex. Palpus small with fine, apical, bristly hairs. The 

 antenna is attached a little below the upper third with 

 the first two segments short; and the first segment 

 longer. The third segment is gradually and slightly di- 

 lated through the middle, more attenuate distally and 

 bears a short, distinct microsegment and a short, stout, 

 attenuate, spine-tipped style no longer than the first 

 anteimal segment. 



Head, anterior aspect: The face below the antenna 

 is about a fifth the head width and only slightly diver- 

 gent below ; the surface is pubescent and apilose. There 

 is a triangle of prominent, stout, mostly pale bristles 

 situated in the middle of the lower half of the face 

 and a row of 4 stout bristles continued down the sides 

 of the concave, pubescent subepistoma. The cheeks are 

 moderately large, nearly bare. Front pollinose, diver- 

 gent ; the vertex is slightly more narrow than the face, 

 only a little excavated anterodorsally, but with a very 

 deep, wide chamiel behind the low ocellarium. The 

 ocellarium bears 2 pairs of short bristles between the 

 ocelli and 2 pairs behind. Sides of front with both 

 upper ocular and lower subocular rows of stout bristles. 



Thorax: The mesonotum is rather high and ante- 

 riorly abrupt with numerous, short, sharp, appressed, 

 unusually stout setae, the whole surface pollinose. 

 Acrostical elements are undifferentiated; the dorsocen- 

 tral elements present only on posterior half with 5 pairs 

 of long bristles. Humerus with fine pile, the lateral 

 complement of bristles consists of 2 stout notopleural, 

 1 supraalar, 1 postsupraalar, 2 postalar, and no scutel- 

 lar bristles. Scutellum thick, convex, with impressed 

 rim and a few, short, marginal and distal setae and a 

 few fine hairs. Pleuron pollinose ; mesopleuron almost 

 without pile but with 2 or 3 hairs in the posterior 

 corner; 1 or 2 very fine hairs are present on the pos- 

 terior basalare. Pronotum with bristles ; upper sterno- 

 pleuron and pteropleuron with a few hairs, posterior 

 hypopleuron and metapleuron with from 1 to 2 stout 

 bristles and a few fine hairs. Metastemum pilose; 

 postmetacoxal area membranous; metanotal callosity 

 bristly pilose; prostemum fused, but reduced postero- 

 laterally. 



Legs : The femora are stout, the first 4 a little swol- 

 len ; the pile on the femora and tibiae is dense, flat ap- 

 pressed and setate, including the ventral surfaces. 

 Bristles are numerous, stout, and rather blunt. Hind 

 femur M'itli 3 dorsolateral, including the subapex, 1 

 medial at the subapex and 1 on each side at the apex; 

 also 3 or 4 ventromedial and a like number of ventro- 

 lateral bristles. Trochanters with bristles. Middle 

 femur with 2 anterior, 3 anteroventral, 3 basal ventral, 



