THE DIPTEEOUS GENUS DOLTCHOPUS IN NORTH AMERICA. 61 



In some of the Labrador specimens the fore tibiae and basitarsi 

 have the same white ring as the middle ones. 



Type. — Believed to be in the University of Lund, Sweden. 



No. 23. DOLICHOPUS ARGENTIPES, new species. 



Male. — Length 5.5 nmi.; of wing the same. Face wide, covered 

 with brown pollen. Front green, the brown pollen of the face 

 extends a little above the antennae and narrowly along the orbits. 

 Antennae wholly black; third joint nearly one and a half times as 

 long as wide, lounded at tip. Orbital cilia wholly black. 



Thorax and abdomen dark green, rather shining; pleurae with 

 gray pollen. The pollen of the abdomen more gray than white, 

 rather abundant. Hypopygium black; its lamellae of moderate 

 size, somewhat oval, but truncate at apex, dark brown without a 

 distinct black border, jagged and bristly on apical margin, fringed 

 above with long black hairs, below with a few short ones. 



Coxae and femora black, knees scarcely paler. Fore and middle 

 coxae with long black hairs on their anterior surface. Middle 

 femora with two preapical bristles, placed very close together so as 

 to appear almost like one; 1 can see but one preapical bristle on hind 

 femora; middle and hind femora ciliated with black hairs below, 

 those on the former shorter, those on the latter longer than the width 

 of the femora. Fore and hind tibiae black, the latter thickened at 

 basal third and at tip, becoming more slender between these points. 

 Middle tibiae black with a white ring, which covers more than one- 

 third their length and is not complete, the lower edge of the tibia 

 being wholly black, the middle basitarsi are also white, with the base 

 and tip narrowly black, the white ground color of the tibiae and tarsi 

 is covered with silvery pollen. Fore tarsi about one and a fourth 

 times as long as then' tibiae, black, first joint with a slightly variable 

 ring, which is not as dark as the rest of the joint. Middle tarsi 

 about equal to their tibiae in length. Hind tarsi whoUy black. 

 Calypters and halteres yellow, the former with black cilia. 



Wings (fig. 23) grayish with a distinctly defined blackish tip, 

 beginning at the tip of second vein; costa slightly enlarged at tip of 

 first vein; last section of fourth vein a little bent at basal third; hind 

 margin of wing indented at tip of fifth vein; anal angle not at all 

 prominent. 



Female. — ^Face as in the male, only slightly wider; third antennal 

 joint shorter; legs and feet wholly black, without any trace of white 

 on middle pair; middle and hind femora not ciliated; middle basi- 

 tarsi without a bristle above, but with several small ones below; 

 wings about as in the male, except that the cloud at tip is not as 

 distinct, and the bend in the last section of fourth vein is a little 

 nearer the middle. 

 187329—21 5 



