40 Annals Entomological Society of America [Vol. VI, 



that I have seen; the male has the tip of the wing infuscated, 

 the hypopygium is darker in color, the pleurae have a black 

 spot above the middle coxae, and the wing veins are darker. 

 The female is difficult to separate from fioridula, but they are a 

 little more robust, and darker in color. 



11 Neurigona flava n. sp. 



Figure 11. 



Yellow, with yellow pollen. Abdomen with lateral brown spots. 

 Wings tinged with yellow. Length -i]/^ mm. 



Female: Face and palpi white; antenna? yellow, the first joint 

 paler, arista brown; front and occiput black, thickly covered with 

 yellowish-white pollen; frontal bristles black, orbital cilia and post- 

 vertical bristles yellowish. Dorsum, scutellum, and metanotum 

 yellow, evenly yellow pollinose, humeri and pleurae whitish-yellow, and 

 yellowish pollenose, a black line in front of the halters. Abdomen 

 yellow, with narrow brown lateral spots on segments three and four; 

 these spots are at the base of the segments and scarcely form bands; 

 hairs of the abdomen mostly black. Legs pale yellow, tarsi scarcely 

 darkened at tip, fore coxse with yellow hairs and black bristles; second 

 joint of hind tarsi longer than first; front and middle metatarsi three- 

 fourths as long as their tibias Wings strongly tinged with yellow, all 

 veins bright yellow; fourth vein ends in tip of the wing, a considerable 

 distance from the tip of the third vein. 



Described from one female in Prof. J. M. Aldrich's collection, and 

 taken at Lewiston, Idaho, on June 17, 1902. 



Note. — This species may be distinguished from transversa 

 by the deeper yellow pollen of the dorsum being evenly dis- 

 tributed; in this species the acrostichal bristles are very poorly 

 developed, while in transversa they are very conspicuous. In 

 this, the second joint of the hind tarsi are distinctly longer than 

 the first, the wings have a strong yellow tinge and the veins are 

 bright yellow, all of which is different in transversa. 



From fioridula it differs by the dense yellow pollen of the 

 dorsum, and the third and fourth veins being much further 

 apart, the wings are also a brighter yellow, but this character 

 is of little use unless the student has both species before him. 



12 Neurigona aldrichii, n. sp. 



Figure 12. 



Thorax and abdomen yellow, the latter with black bands; hj^po- 

 pygium black 'and yellow; second joint of front tarsi shorter than the 

 fourth, flattened, and widened at tip. Length 3-3^ mm. 



Male: Face and palpi white; eyes contiguous; antenna and pro- 

 boscis yellow, arista brownish yellow; front and occiput dark grayish 

 green with white pollen; orbital cilia whitish. Thorax yellow, shining; 



