ZooL.— Vol. II.] WHEELER— DOLICHOPODIDM. 25 



white, prominent. Thorax submetallic brownish black, with four distinct 

 gray vittae. The mesial pair fuse at the neck but remain separate up to 

 the scutellum, thus enclosing a median brown stripe even on the pre- 

 scutellar depression. Before the sides of the scutellum each mesial gray 

 stripe fuses with a lateral gray stripe which runs forward only half the length 

 of the thorax. There is a distinct accumulation of gray dust on the humeri 

 and in the posthumeral depressions. The black bristles on the anterior 

 portion of the thorax are small, but laterally and posteriorly they are long 

 and well developed. Scutellum covered with gray dust and bearing fouil^black 

 bristles. Abdomen shining bronze-black, the bases of the separate segments 

 opaque with gray dust. Hairs covering the segments short, in some lights 

 black, in others yellowish. Hypopygium long and moderately slender, 

 shining black, appendages short and indistinct, somewhat yellow at their 

 tips. The hairs on the lower (morphologically dorsal) surface of the organ 

 are rather short. Pleurae black, overlaid with a thin layer of gray dust. 

 Bristles above the fore coxae and the hairs on the anterior surfaces of the fore 

 and middle coxse black. Legs black throughout. Hind tibia and metatarsus 

 plain. Second joint of hind tarsus about one and two-thirds times as long as 

 the metatarsus. Wings hyaline with veins black almost to their bases. Distal 

 segment of fifth vein only half as long as the posterior cross- vein; tips of the 

 third and fourth veins close together. Halteres yellowish on the under side 

 but distinctly blackened and dusted with gray on their upper surfaces. Teg- 

 ulse yellow, edged with black and bearing rather long white cilia. 



One specimen of this handsome species from Moscow, 

 Idaho, taken during September by Professor J. M. Aldrich. 



26. Medeterus princeps, sp. nov. 

 Plate H, Figs. 29-32. 



Male. Length 4-4.5 mm. ; length of wing 4-4.5 mm. Proboscis much swol- 

 len, very glabrous, black. Palpi black, shining, with yellow hairs. Face below 

 suture very bright metallic green, glabrous; just below the insertions of the 

 antennae there is a thick layer of yellowish dust; between these two regions 

 the metallic green ground-color is exposed, but is not so glabrous as the re- 

 gion below the suture. Antennae black, arista subapical, nearly as long as 

 the face and the proboscis. Front and occiput densely covered with yellow- 

 ish gray dust, faintly revealing the metallic green ground-color. Thorax 

 metallic green but subdued to a satiny luster by.the heavy layer of gray dust 

 investing it, with five brown, somewhat iridescent vittae; the three mesial of 

 which fuse posteriorly to form a large brown patch covering the prescutellar 

 depression; the lateral pair are shorter, terminate at the insertions of the 

 wings posteriorly and fuse with the adjacent mesial band anteriorly. Acros- 

 tichal and dorsal bristles black. Scutellum uniform submetallic greenish gray, 

 with four black bristles. Abdomen of the same color as the scutellum, the 

 segments covered with short yellow hairs. Along the sides of the segments 

 the smooth black depressions are conspicuous and elongated. Hypopygium 



