248 ERNEST A. BACK. 



black pile narrowly bordering the occipital orbits is hardly perceptible. 

 Pile of thorax and abdomen very short, appressed, thickest on the 

 sides of the dorsum and on the pleurae of the thorax and on the sides 

 of the abdomen. Legs wholly black, only slightly clothed with very 

 pale pile and on the tibiae and tarsi with very weak, inconspicuous 

 bristles; coxae with long, coarse pile; claws black, reddish at base; 

 pulvilli pale. Wings dusky hyaline, darker along the costa; the veins 

 very slightly bordered with fuscous; the whole of the second basal, 

 anal, axiliary and discal cells milky-white. 



Type. — Two male co-types, deposited one each in the col- 

 lection of the Massachusetts Agricultural College, and that 

 of the Montana Agricultural College. 



Habitat. — Bozeman, Mont., 4,800 ft. elev. (June 25, E. 

 Koch); Col. 



ECHTHODOPA. 

 Echthodopa Loew, Cent., VII, 27, 1866. 

 Echthopoda Loew, Beschr. Europ. Dipt., II, 78, 1871. 

 Echthodopa Schiner, Verh. Zool.-Bot. Ges., XVI, 846, 1866. (Quotes 

 orig. desc.) 



Echthodopa does not differ from Dioctria except that the 

 lower third of the face is convex and bears a dense mystax; 

 and that the middle and hind femora bear several short strong 

 bristles. In Dioctria the femora are without bristles. The 

 only two species in the United States belonging to this genus, 

 formosa and pubera, are larger and more robust than our 

 species of Dioctria. 



Type. — Echthodopa pubera Loew 



SYNOPSIS OF SPECIES. 

 Pile of palpi black; wings nearly hyaline; Eastern species ....formosa. 

 Pile of palpi yellowish; wing- veins bordered with fuscous; Western 

 species pubera. 



Echthodopa formosa. 



Echthodopa formosa Loew, Cent., X, 22, 1872. 



$ $. — Length 13-17 mm. — Polished black, tibiae clear bright yellow, 

 except their distal portions; mystax golden in the male, whitish in the 

 female; the palpi of both sexes, and the rather large hypopygium of 

 the male with black pile. 



Black; tibiae clear bright yellow except the distal third of the fore 

 and middle, and the distal two-fifths of the hind pair, which are dark 

 chestnut. Face narrower in proportion than in pubera, with a dense 

 golden pubescence; front polished black. Mystax dense, golden in 



