221 
Genus Megarhinus. 
mid legs unequal, the large one toothed; in the hind legs equal 
and simple. 
Wings with the veins covered with small, but rather broad 
scales, some in the form of elongated triangles, brown, with here 
and there azure-blue ones ; first sub-marginal cell very small and 
the branches widely divergent, its stem very long, joining the 
first long vein a little way past the supernumerary cross-vein ; 
second posterior cell about twice the length of the former, its 
stem about twice as long as the cell and carried past the cross¬ 
veins into the basal cell; mid cross-vein small, some distance 
nearer the base of the wing than the supernumerary, posterior 
cross-vein long and joining the mid cross-vein; base of the wings 
bright ferruginous. 
Halteres with ferruginous stem and fuscous knob. 
Length. —10 to 11 mm., with palpi, 19 mm. 
9 . Head with metallic green scales in the middle, blue in 
front and purple at the sides ; antennae dark brown, basal joint 
rotund, small and nude, steely black, with grey reflections, rather 
longer than the first four joints of the palpi; palpi covered with 
steel-blue scales, the third joint nearly twice as long as the 
second, the latter about equal to the fourth (last missing) ; 
proboscis long coppery brown. 
Thorax dark brown, covered with olive-green scales; pro- 
thoracic lobes with blue scales; pleurae brown, with silvery 
scales; scutellum and base of the mesonotum with flat azure-blue 
scales, a small dense tuft of brown bristles over the roots of the 
wings ; metanotum chestnut-brown. 
Abdomen with green, dark blue, purple, and then coppery-red 
scales, some white in the middle, with lateral, red, caudal tufts, 
sides with metallic golden and azure patches. 
Legs metallic blue and purple; in the hind legs the first 
tarsal joint and part of the second are white ; hind metatarsus 
not quite as long as the tibia; hind ungues simple and equal, 
fore and mid legs damaged ; wings with the veins clothed with 
purple scales, dusky along the costal border, the first sub- 
marginal cell very small; mid and posterior cross-veins united, 
forming a widely obtuse angle; halteres pale, with slightly 
darker knob. 
Length. —8 to 9 mm. 
Habitat. —Para, Brazil (Walker) ; Cayenne; Chaco in 
Formosa ; Argentina ; Rio de Janeiro (Lutz); Lower Amazon 
(Austen, 96, 80). 
