550 THEREVID^ 



Legs dull blackish, but tlie tibiae dull orange except at the narrow in- 

 definite blackish tip, and the tarsi dull orange about the base of the basal 

 joint of the front pair and on most of the two basal joints of the posterior 

 pairs except at their tips ; front part of the hind femora covered with yellow 

 scaly hairs. Pubescence fairly abundant and long behind and beneath the 

 anterior femora, brownish yellow with numerous long black hairs intermixed ; 

 front coxse with two black bristles, middle coxae with four, and the hind 

 coxa3 with one ; other bristles strongly developed in accordance with the 

 generic characters. 



Wings with a distinct yellowish tinge which becomes positively orange 

 on the subcostal vein and on the basal part of the postical vein, while the 

 cubital vein from its base to its fork and the upper branch of the postical 

 fork (with the exception of its basal part) are also rather orange ; sometimes 

 there is a slight suspicion of darkening about the upper outer angle of the 

 discal cell ; when viewed from the wing-tip the orange colour about the base 

 and stigma is conspicuous. Squamae (alar) small, glassy yellowish with 

 a blackish base, brownish margins, and a short rather dark fringe. Halteres 

 orange, with the base of the knob sometimes brownish. 



? . Eesembling the male, but distinguished by the usual sexual characters. 

 Frons occupying less than one-fifth of the head at the vertex but steadily 

 widening downwards, dull dark rich golden at the top but with a large 



brilliantly shining black obcordate callus — or (say) 

 a brilliant black crossband from eye to eye, which 

 sends a broad bend upwards in the middle almost 

 to the ocelli, but on the lower side has a con- 

 spicuous narrow triangular emargination (fig. 320) 

 — while below this shining black callus the frons 

 just above the antennae is dull golden ; pubescence 

 on the frons mainly black but partly tawny, not 



^^^ ^ dense from the vertex almost down to the antennae, 



^^^^^iMP''''?^^^^^ ^'^^ leaving the shining black callus bare except 



' --'■M4%tW'''W^^^^ anteriorly at the sides, though the pubescence just 



Fig. sio.—Therevafuiva ?. above and about the antennae is yellow ; face pale 



X 16. yellow and bearing dense pale yellow pubescence, 



while similar pubescence is continued round under 



the eyes and up the back of the head, Imt as it ascends becoming tawny 



until it reaches the black hairs of the vertex, and there is a postocular row 



of about twelve stout black (almost) bristles on the upper part of the head 



which bend slightly forwards, while in addition about sixteen black bristles 



right out on the upper part of the back of the head are continuous from 



side to_ side ; one or two black hairs occur immediately under the eyes, but 



otherwise there are no black hairs after those on the frons down the face 



and round the jowls and back of the head until the postocular bristles ; back 



of the head moderately puflfed out. Antennae Avith the fine yellow pubescence 



about the base of the basal joint short. 



_ Thorax with the ground colour much more obvious and with a pair of 

 faint narrow paler stripes down the disc ; pubescence mainly short, recum- 

 bent, tawny, and hardly dense enough to conceal the ground colour, l3ut still 

 with several of the rather longer erect black hairs all over the disc, besides 

 the black chaetotactic bristles of which the praesutural are usually four in 

 number but sometimes three on one side and four on the other • praescutellar 

 pairs two as in the male ; j)leurae with rather long thin yellow hairs in which 

 no black hairs are intermixed, and the tuft on the metapleurae still dense 

 and conspicuous ; the ground colour of the lower part of the pleurae is light 

 ashy grey. Scutellum with tawny pubescence, amongst which no black 

 hairs occur except the four long margintil bristles. 



Abdomen with the six basal segments entirely dull fulvous except for 

 a narrow shining black base on the fifth and sixth, and these six segments 

 bear an abundant depressed yellow pubescence which becomes fairly long 

 and more erect and conspicuous about the basal corners and rather long 

 on a praehindmarginal fringe on the basal segment, but all over the disc 

 the pubescence is short and depressed and without a trace of black hairs 



