226 BULLETIN 116, UNITED STATES NATIONAL MUSEUM. 



hind coxao black with yellow tips. Hind trochanters brown, the 

 four anterior ones with a brown spot. Femora and tibiae yellow. 

 Middle femora with one preapical bristle, the hind pair with a row of 

 bristles of increasing size, ending in the usual preapical bristle, with 

 out cilia below. Posterior tibiae thickened and a little compressed, 

 with a glabrous groove on inner side, the glabrous stripe on upper 

 surface narrow but distinct. Fore tarsi about as long, middle ones 

 scarcely as long as their tibiae, infuscated from the tip of the first 

 joint, still the second joint often yellow at base; first joint of fore 

 tarsi a little shorter than the remaining four taken together, the 

 fourth slightly the shortest of all. Hind tarsi black from apical third 

 of first joint. Calypters, their cilia and the hal teres yellow. 



Wings (fig. 168) grayish, sometimes narrowly a little brownish 

 along the cross-vein ; costa thickened at tip of first vein for a distance 

 equal to one and one fourth times the length of the cross-vein, this 

 thickening is truncate and provided with a little spur at apex; last 

 section of fourth vein sharply bent before its middle; hind margin of 

 wing notched at tip of fifth vein; and with a slight sinus at tip of 

 sixth vein; anal angle rounded, but rather prominent. 



Female. — Face wide, silvery; fore coxae clothed on their anterior 

 surface with stifip black hairs; wings as in the male, except that there 

 is scarcely a trace of the sinus at tip of sixth vein and the costa is not 

 enlarged at tip of first vein. 



Redescribed frona 16 males and 8 females, which includes 10 type 

 specimens; the 10 types are from Moscow, Idaho; the others were 

 taken at Moscow, Idaho, September 12, 1908; Stanford University, 

 California, October 7, 1905; these were taken by J. M. Aldrich. Baker 

 took it in Santa Clara County, California, and in Colorado. S. J. 

 Hunter at Rock River, Wyoming, July, 1913. 



Types. — In collection of J. M. Aldrich. 



No. 164. DOLICHOPUS CAVATUS, new species. 



Male. — Length 5 mm. ; of wing 4-4.5 mm. Face moderately wide, 

 silvery white, tinged with yellow below the antennae. Front green 

 with bronze reflections. Antennae black; first and second joints 

 yellow below, first of normal size; third somewhat orbicular in out- 

 line, scarcely pointed at tip. Lateral and inferior orbital cilia white, 

 the lower ones silvery and flattened, about fourteen of the upper 

 cilia on each side black. 



Thorax green with bronze reflections, and usually with a cop})ery 

 spot on each side of the dorsum, which is dulled a little with yellow- 

 ish pollen; pleurae dulled with white pollen. Abdomen green with 

 coppery reflections; the white pollen on its sides is not conspicuous 

 and has a yellowish tint. Hypopygium black; its lamellae (fig. 

 164a) of moderate size, somewhat oval in outline, but with edges 



