and half as long as body. Labella lighter in colour, expanded, few hairs showing (in male many hairs are seen). Palpi (Fig. 51) 2-jointed, one-third length of proboscis; black scaled except for a ring of silvery-white scales in the middle; few bristles are seen.

Fig. 50.—Rachionotomyia argyropus ♀.

Antennae 14-jointed, two-thirds length of proboscis, pilose (male plumose); first flagellar segment paler than the others. Ground colour dark, joint membranes lighter in colour; covered with numerous short stiff light brown hairs, long black verticillate hairs on joints; penultimate and antepenultimate joints twice the length of others. Clypeus deep brown, many black bristles projecting forward. Torus golden yellow carrying many short stiff black hairs internally situated. Eyes large, black, with a coppery sheen. Frons filled up by a dividing black line. Nape and occiput black scaled. Above the nape and below the eyes is a circular fringe of flat pastel-blue scales. On the lower part of the fringe is a border of strong black bristles projecting forward. On the nape are several upright black scales.

Thorax ferruginous anteriorly, becoming much darker on the mesonotum on account of a covering of short narrow curved black scales; some light golden bristles also present are too scattered to affect the general coloration. Prothoracic lobes yellow, with several strong dark bristles; scutellum ochraceous, trilobed, with several golden bristles projecting backwards and partly covering the metanotum. Metanotum black.

Pleura yellow, with a silvery-white stripe across it. Pleural pilotaxy (Fig. 52): The protergum is light golden in colour, carrying

6 to 8 light-coloured pronotal bristles, and two black ones. The pro-episternum is same colour, with 6 to 8 prosternal bristles. Pro-epimeron with 2 to 4 pro-epimeral bristles arranged on the posterior margin, protecting the first spiracle. The spiracular area has no

Fig. 51.—Palpus of ♀. Fig. 52.—Pleural pilotaxy of R. argyropus.

bristles to cover the first spiracle, this function being performed by the pro-epimeral chetae in this species; it has two posterior bristles on the apex. The mesepisternum has from 3 to 7 pre-alar but no sternopleural bristles. The mesepimeron has 10 to 12 upper mes-epimeral bristles arranged to cover the second spiracle; lower mesepimeral bristles are wanting. A broad stripe of silvery-white imbricating scales passes across the lower part of the mesepimeron and on to the pro-episternum; there is another broad stripe on the margin of the mesonotum.

Wing (Fig. 53): Length 4 mm., longer than proboscis, and reaching beyond the last abdominal segment. Fork cells long and nar-

row, Cell R.2 slightly longer and narrower than Cell M.2 their bases not quite opposite, that of the former being more proximal; stem of R.2 shorter than that of M.2, and rather more than one-third length of its cell; stem of M.2 more than twice length of its stem. Supernumerary

Fig. 53.—Wing of Rachionotomyia argyropus.
Fig. 54.—Median scale.
Fig. 55.—Lateral scales.
Fig. 56.—Fringe scale.

and mid cross veins opposite; posterior cross vein three times its own length distant from mid cross vein. Median scales (Fig. 54) very broad and short; lateral scales (Fig. 55) longer, narrower and curved; fringe scales (Fig. 56) long and tapered. Haltere with pale yellow stems, knobs with bluish-grey scales.

Legs brownish-black, distal ends of each segment darker than proximal. Coxa and trochanta yellow. Fore-leg: Femur black at base, changing to dark brown distally except for a patch of white scales on the apical four-fifths; apex, or knee joint white. Tibia dark

brown, almost blue black in some lights; apex and knee joint with faint bluish-white scales. Tarsus: The fourth segment and part of the third are white; the fifth is black except for a few white scales on the ventral surface which gives it a dull sheen. Mid-leg: Femur as in fore-leg. Tibia also as in fore tibia except that it lacks the apical scales. Fourth and fifth tarsal segments chalky white. Hind-leg: Femur with distinct white patch at apical four-fifths, apex and knee joint white. Tibia with white patches at apex and knee joint. Apex of third, all of fourth and of fifth tarsal segments white; total length of tarsus half as long again as tibia. Ungues small, simple, curved, black; of fore- and mid-leg curved, simple black; of hind-leg smaller, almost straight and black.

Abdomen covered with flat fuscous scales, the testaceous ground colour showing through where the dark scales have become lost; anterior portions of each segment yellow, their posterior borders carrying a number of golden hairs; each segment with silvery-white lateral apical scales. On the ventral surface the segments are white-scaled apically. Posterior segment short and strongly bristled.

Total length 7 to 7.5 mm.

Fig. 57.—Unguis of ♂ fore-leg.
Fig. 58.—Hypopygium of R. argyropus.

Male: Palpi as in female. Ungues of fore- (Fig. 57) and mid-leg curved, black; of hind-leg smaller, almost straight, also black. A feathery appendage springs from the base of the unguis, and two strong slightly curved and tapered spines arise from the dorsal portion of the distal end of the fifth tarsal joint.

Hypopygium (Fig. 58) with short oval basal lobes, heavily bristled throughout; claspers long, narrow and gradually tapering to an acute point. The harpago area and the phallosome together are