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UNITED STATES NATIONAL MUSEUM BULLETIN 224 



the first and second segments is reduced to 1 to 3 short, 

 slender, bristly hairs. 



Head, anterior aspect : The face below the antenna is 

 only one-seventh the head width and divergent below 

 to one-fourth the width. Subepistomal area large, 

 long and oblique, nearly as long as the face. The face 

 is everywhere pubescent, apilose, the epistomal mar- 

 gin with about 5 pairs of fine, slender, moderately long 

 bristles. The front is pollinose, very greatly expanded 

 to the vertex, which is more than half as wide as the 

 head. There is virtually no excavation of the vertex; 

 the small ocellarium is low, no higher than the lateral 

 ocellus and bears a pair of stout, anteriorly curved 

 bristles between the posterior ocelli. Anterior eye 

 facets extraordinarily enlarged in both sexes. 



Thorax : The thorax is appressed micropubescent, the 

 metanotal height is half its length. The pile of the 

 mesonotum is scanty, rather fine, long and bristly, and 

 not differentiated. In the type of genus the following 

 complement of bristles is present: 2 long, slender but 

 prominent notopleural, 1 supraalar, 1 weak postalar, 

 3 or 4 pairs of fine, short bristles on the scutellum, and 

 2 long prescutellar bristles. Scutellum, flat, densely 

 pubescent. Propleuron with little or no pile except a 

 few fine hairs on the collar; upper mesopleuron with a 

 single fine hair; metapleuron with 4 long, fine bristly 

 hairs; remainder of pleuron pubescent only. The 

 metanotal slopes are micropubescent only ; lateral meta- 

 sternum and the narrow ventral metasternum chitin- 

 ized and apilose; postmetacoxal region completely 

 chitinized and pubescent ; tegulae micropubescent only. 

 Prosternum not dissociated. 



Legs : The femora are comparatively stout and short, 

 the hind pair slightly dilated distally. In the type of 

 genus the pile is everywhere quite short and more or 

 less appressed. Hind femur with 2 well developed 

 apical bristles, an anterodorsal and a dorsomedial; its 

 tibia with 3 minute, dorsal basal bristles and 1 or 2 

 lateral, also on the basal half, but with a long, conspicu- 

 ous bristle dorsolaterally just beyond the middle, 1 

 nearly opposite ventrolaterally, and a third laterally 

 a short distance back from the apex. Middle femur 

 with similar apical bristles, 1 well developed antero- 

 dorsal at the apical fifth, and 1 posteriorly closer to the 

 apex; its tibia with 5 or 6 fine dorsal bristles, 3 long 

 anteroventral and a like number of posteroventral 

 bristles, all oblique, stout and attenuate. Anterior fe- 

 mur with 2 dorsal bristles, one near the apex, one an- 



terodorsal at the apex, and a third opposite and pos- 

 terodorsal; its tibia with 3 or 4 quite minute dorsal 

 bristles scarely noticeable but with 4 conspicuous, stout, 

 attenuate posteroventral bristles. No spine. The 

 bristles of the first two tarsal segments are well devel- 

 oped. All tarsi end in sharp, slender claws, well 

 developed pulvilli, and a fine empodium. 



Whigs : The wings are comparatively slender, attenu- 

 ate basally. Marginal cell widely open but the second 

 vein ends some distance back from the apex and the 

 subcostal vein ends still further and opposite the an- 

 terior crossvein. All of the posterior cells widely open, 

 the third completely eliminated, so that only four cells 

 are present. The anterior crossvein lies quite far 

 toward the base of the discal cell and the subcosta ends 

 opposite to it. The discal cell appears to end with one 

 vein, the second basal cell with three, the anal cell is 

 closed with a long stalk. The alula is absent ; ambient 

 vein complete. 



Abdomen: The abdomen is slender, but not quite as 

 wide as the mesonotum, somewhat flattened, with nearly 

 parallel sides on the first four or five tergites. Male 

 with eight well developed tergites, the last being about 

 as long as the seventh. Female with eight tergites, the 

 eighth a little longer than the seventh. Pile of abdomen 

 rather abundant, delicate, fine, erect, and scarcely longer 

 laterally. Sides of the first tergite with 2 or 3 fine, 

 bristly hairs. Male terminalia conspicuous, elongate, 

 not rotate. Epandrium of the ninth tergite notched 

 apically but not split. The epandrium is prominent, 

 turned strongly downward and armed laterally, as in 

 Stichopogon Loew, but shorter and less sloping pos- 

 teriorly; not pollinose. Proctiger similar to Sticho- 

 pogon. Gonopod elongate, tightly apposed to lower 

 edge of epandrium. Hypandrium with deep sulcus re- 

 duced almost to nothing in the middle. Eighth sternite 

 reduced to a mere line in the middle. Female terminalia 

 with 4 pairs of long, conspicuous, slender, apically 

 blunt, spoonlike spines. Ventral plate protiiisive, more 

 or less pinched together and split to near the base. 



These small flies can be found frequenting low grow- 

 ing grass and herbs of sandy areas quite close to the 

 margin of shallow streams. 



Distribution: Nearctic: Townsendia niger Back 

 (1909) ; pulcherrima Back (1909). 



Neotropical: Townsendia argyrata Curran (1926); 

 ficbrigii Bezzi (1909); minuta Williston (1895); 

 podexargenteus Enderlein (1914). 



Tribe Stenopogonini 



In this tribe are assembled all the higher Dasypogon- 

 inae, whose front tibiae lack apical spines, and whose 

 females have spines on the acanthophorites. It is a 

 larger group than the Dasypogonini and contains about 



75 genera. It contains 3 genera, which are quite large 

 in terms of species ; these are Stenopogon Loew, Cyrto- 

 pogon Loew, and Microstylum Macquart. The accom- 

 panying key differentiates the genera of this tribe. 



