13. DIOCTRIA 743 



extending vaguely upwards on the inner (=front) side almost to the base: 

 anterior tarsi black or dark brown with the necks of the joints orange and 

 with rather consi)icuous orange bristles and pubescence ; hind legs black, but 

 orange on the trochanters, the base of the femora (more or less distinctly), the 

 apical third (or less) of the femora except on the upper side, and the extreme 

 base of the tibiae ; hind tarsi with the basal joint, and tlie hind tibite at 

 just the tip, considerably dilated. Anterior coxte densely covered with 

 pale_ greyish yellow tomentum and anteriorly with long drooping 

 whitish yellow pubescence ; hind coxae with less dust, and with only slight 

 short ptile pubescence about the tip ; anterior femora witla a few long thin 

 pale hairs beneath near the base ; front tibiai with about three widely 

 separated very thin long jiale postero-ventral hairs, and with three stronger 

 also widely separated orange posterior bristles (and a small one near the base), 

 but with the usual dorsal bristles very small and inconspicuous ; middle tibite 

 with the usual Ijristles, l)ut the two postero-ventral (one at and one after the 

 middle) long, and the two antero-dorsal (one at one-third from the base and 

 the other at two-thirds) also long; hind femora Avith one strong though 

 rather short orange anterior bristle not far from the base which usually 

 stands out rather distinct from the others, and with a few long jmle hairs 

 among the furry pubescence beneath ; the furry pubescence whitish and so 

 long that it is hardly of a furry nature, while that on the tibije is more 

 brownish yellow ; hind tibia; with one orange antero-dorsal bristle at one- 

 third of its length and one at two-thirds, and about five dorsal bristles 

 almost equally separated (the last one being apical) ; the close short bristly 

 pubescence on the hind tibiai and above the hind tarsi is black, but all the 

 longer bristles on the legs are orange. Pulvilli dark orange ; claws dark 

 orange at the base. 



Wings (fig. 400) slightly greyish, with usually the base and the costal and 

 upper basal cells tinged with brown which may also enclose the stem of the 

 postical vein; fourth posterior cell slightly narrowed at the tip. Alar 

 stiuamte dirty brownish yellow with a yellow margin, on the lower portion of 

 which is a very short whitish yellow fringe. Halteres varying from pale 

 yellow to canary yellow, or even to a brownish orange stem and a brown knob. 



?. Very similar to the male. Face-beard not quite so much in a single row; 

 the shimmering white postocular portion of the back of the head extending 

 further up but less defined. 



Abdomen usually more distinctly reddish orange at the hind corners 

 of the third to sixth segments and narrowly along the hindmargins for a 

 short distance, though the two last segments usually have the hindmargins 

 narrowly orange all across, of which the preceding segments have traces. 



Legs inclined to be paler, the black streak on the upper side of the 

 anterior femora being usually rather narrower and the under portion more 

 clearly orange ; middle tibite sometimes hardly blackened anteriorly ; hind 

 femora rather more orange, a broad black ring occupying rather more than 

 their middle third and extending dorsally almost to the tip, while the basal 

 third is yellow rather than orange ; hind tibiae with nearly the basal third 

 indeterminately reddish orange ; minute pubescence on the hind tarsi pale. 

 Hind femora with two or three anterior bristles on the basal half. 



Wings perhaps a shade more hyaline. Squamaj clearer yellow. 



Length ( ^ ) about 9 mm., or ( ? ) about 9 mm, to 1 1 mm. 



This species varies considerably iu the amount and intensity of the 

 blackish coloring of the legs, which is however never rednced to such a 

 small amount (even in immature specimens) as to render its distinction 

 from D. hycdvpennis * at all difficult; the palest forms have the upper side 

 of the anterior femora streaked with black, and the hind femora broadly 

 black about the middle and on the upper side almost to the tip, while the 

 basal joint of the front tarsi has scarcely more than its narrow neck 



* Luiidbeek (Dipt. Danica, Part 1 1., -lb) has proved that Meigen's D. flavipes is a synonym of A. 

 hyalipennis of Fabricius, as had been pointed out by Loew sixty yt-ars pieviously. 



