OSTEN SACKEN ON WESTERN DIPTERA. 297 



black, the hind margins of the segments 2-5 with white triangles on 

 each side. The hairs on head and chest are like those of the male, but 

 of a less pure white ; the white hair on the sides of the abdomen reaches 

 to its tip, gradually becoming shorter. Legs like those of the male, but 

 the sexual ornaments on the front and middle tarsi are wanting. Wings 

 with the grayish tinge a little more saturate than in the male. 



Length, $ ll-12 mm ; 9 ll-13 mm . 



Hab. — Yosemite Valley, California, June 5-12 ; Summit Station, Sierra 

 Nevada, July 17 ; Webber Lake, Sierra County, California, July 22-26. 

 Eight males and seven females. 



Dr. Loew (1. c.) has given a very detailed description of the male ; 

 that of the female must have been taken from a very imperfect specimen, 

 as it is not recognizable. 



2. Cyrtopogon cymbalista n. sp., $ 9 . — Male. — Like the preceding 

 in the ornamentation of the four anterior tarsi and in the general col- 

 oring of the body, but with the following differences : — 



The abdomen is uniformly clothed with black pile. The white pile on 

 the lower part of the occiput and on chest and front coxae is less long 

 and conspicuous. The black pile on the upper part of the occiput 

 , reaches much lower here. Only the four anterior femora have some 

 ! white pile on their posterior side. The brownish pollen on the thorax 

 is hardly perceptible here. The front tibiae and the tips of the four hind 

 tibiae are black. Besides the silvery hair on joints 2-5 of the front tarsi, 

 I some silvery pile is also perceptible on the first joint. The under side 

 of the same tarsal joints is not beset with dense brushes of short black 

 ' bristles, as it is in G. callipedilus, so that the white silvery hairs are 

 visible from below, which they are not in the other species. The pul- 

 villi of the four hind tarsi are brown, while in G. callipedilus they are whit- 

 i ish. The wings are a little shorter. The abdomen is slightly tapering 

 from base to tip, instead of being nearly cylindrical, as in G. callipedilus. 

 ! A vestige of a spot of whitish pollen is generally visible in the hind cor- 

 ner of the fourth segment. 

 1 Female. — Black, shining; thoracic dorsum with a slight brownish pol- 

 1 len, which is a little denser than in the male, but much less dense than in 

 G. callipedilus ? . The hair on the face is deep black ; a little whitish 

 I pile on the lower part of the occiput and on the front coxae ; pile on the 

 j legs black ; their coloring the same as in the male; only the front tibiae 

 ! sometimes are reddish at the base and along their front side ; abdomen 

 i with small triangles of whitish pollen on the hind corners of segments 

 ] 2-4, the largest on the fourth segment. The shape of the abdomen is 

 j different from that of G. callipedilus 2 ; gradually tapering from base to 

 tip, instead of slightly expanding about the middle. Length, $ ll-12 mm ; 

 9 12-13 mm . 



Hab. — Summit Station, Sierra Nevada, July 17 ; Webber Lake, July 

 23-24; both sexes found in each locality. Three males and four females. 



3. Cyrtopogon plausor n. sp., $ 9 . — Very like the two preceding 



