234 BULLETIN 116, UNITED STATES NATIONAL MUSEUM. 



inner appendages wliich arc more conspicuous than usual; they have 

 a rather large, triangular, brown tip. 



Fore coxae yellow, with the extreme base on outer side brown; 

 their anterior surface with silvery pollen and minute yellow hairs. 

 Middle and hind coxae black with yellow tips. Femora and tibiae 

 yellow, each with one preapical bristle, the latter without cilia be- 

 low, still with a row of delicate little yellow hairs on lower inner edge. 

 Posterior tibiae not thickened, the usual glabrous stripe on upper, 

 surface broken up by little hairs, but inside of the inner row of large 

 bristles is a glabrous stripe, widest near the base and reaching nearly 

 to the tip. Middle tibiae with one bristle below, their basitarsi 

 without a bristle above. Fore tarsi scarcely one and a fourth times 

 as long as their tibiae, first joint a little longer than the three follow- 

 ing joints taken together, fourth and fifth of nearly equal length. 

 Middle and hind tarsi about one and one-third times as long as their 

 tibiae; all tarsi black from the tip of the first joint. Calypters and 

 halteres yellow, the former with black cilja. 



Wings (fig. 170) grayish, with a conspicuous brown spot near the 

 tip, extending from the costa back of the fourth vein and from the 

 bend in the fourth vein to the apex of the wing; costa with a small 

 knotlike enlargement at tip of first vein; last section of fourth vein 

 a little bent beyond its basal third; wings long and narrow, of some- 

 what equal width, narrowest at tip of fifth vein, where there is a small 

 sinus; between the fifth and sixth veins the hind margin has an out- 

 ward swell; anal angle prominent, with a lobe extending toward the 

 root of the wing; hind margin fringed with conspicuous but very 

 delicate hairs. 



Female. — Face wide, silvery white; legs and tarsi as in the male, 

 except that the glabrous stripe on upper surface is more distinct, but 

 the one on inner surface is wanting; wings (fig. 170ff ) without a brown 

 spot, of normal form, rather evenly rounded behind, scarcely in- 

 dented at tip of fifth vein; costa without an enlargement; anal angle 

 rounded, rather prominent. 



Described from 8 males and 2 females. J. M. Aldrich has 1 pair 

 taken at Franconia, New Hampshire, and 1 male from Roxborough, 

 Pennsylvania (Harbeck), June 7. The United States National 

 Museum has 1 male from the White Mountains, New Hampshire. 

 Mr. N. Banks took 1 at North Fork, Swannanoa, Black Mountains^ 

 North Carolina, May. C. W. Johnson took it at Mount Washington, 

 New Hampshire, July 21; Glen House, New Hampshire, July 23; 

 Mount Greylock, Massachusetts, July 25; and 1 female at Capens, 

 Maine, July 16. 



r!//;e.— Male, Cat. No. 23049, U.S.N.M.. from Roxborough, Penn- 

 sylvania. 



