250 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



side of the third segment ; the fur on the chest more whitish ; ground- 

 color of the thorax deep black. Hal teres yellow. Legs black ; base of 

 tibiae brown ; femora and tibiae beset with whitish-yellow scales. Prox- 

 imal part of the wings tinged with pale reddish brown as far as the tip 

 of the first vein and the anterior and posterior cross- veins 5 the brown 

 gradually evanescent about this limit ; the remainder, of the wing gray- 

 ish-hyaline. 



Female. — Like the male in all respects, except that the fur is much 

 more whitish, including that of the mystax. The front is clothed with 

 some scattered, erect, whitish pile, and a very dense, recumbent, pale 

 whitish-yellow, shining tomentum, completely covering the ground- 

 color, except on the vertical triangle and a Hue in the center of the 

 front ; some black hairs above the mystax, but none on the front and 

 vertex; the brown on the wings less dark and extended; the ground- 

 color of the femora and of a part of the tibiae concealed under a thick 

 covering of whitish scales. 



Length about 6.5 mm . 



Hob. — Webber Lake, Sierra Nevada, California, July 25. A male and 

 a female. Will be easily recognized by the dense hairy clothing of the 

 face and the shape of the antennae. The paler fur of the female speci- 

 men I hold to be varietal and not sexual. 



0. Bombylius cachinnans n. sp., 2 $ .— Body black, densely clothed 

 with a dull yellowish fur; epistoma brownish-yellow in the female, 

 darker in the male, and covered with grayish pollen ; the longer hairs 

 upon it are black ; the shorter pile round the edge of the mouth is 

 golden-yellow. Frontal triangle in the male grayish-pollinose, and with 

 black pile ; in the female, the opaque grayish-black front is beset with a 

 recumbent reddish-golden short tomentum, the ocellar tubercle and sur. 

 roundings being free from it; some scattered black erect hairs are 

 visible on the sides of the front and on the vertex ; proboscis nearly as 

 long as the body ; antennae with black pile on the basal joints ; the 

 third joint is rather narrow in the male and somewhat broader in the 

 female, and of equal breadth for more than half of its length, beyond 

 which it is narrower. The fur on thorax and abdomen is of a nearly 

 uniform color ; on the hind margins of the segments of the latter, some 

 sparse black hairs may be perceived, which appear as indistinct tufts 

 on the sides of the second and of the following segments. Wings gray- 

 ish-hyaline, tinged with pale brown or reddish-brown at the base and 

 in the costal cell ; in the female, the brown does not fill out the distal 

 half of the first basal nor the second basal cell ; in the male, the brown 

 is darker, and gradually evanescent posteriorly, but it extends over 

 nearly the whole wing. Legs yellowish-red ; tarsi, except their base ? 

 black ; in the male, the base of the femora is black ; the knees have 

 black dots on the front side. Length of male 6.5 mm ; of female 7-8 mm . 



JIab. — Sonoma County, California, April 27-May 9. Two females 

 and one male. 



