294 ERNEST A. BACK. 



the species from the West now placed under Cyrtopogon. The 

 structure appears to be the same as the species described by 

 Bigot as Holopogonf appendiculatum, but it cannot be the 

 same species, as will be seen by comparison of the description 

 of the thorax, abdomen, legs and wings. Cyrtopogon cerus- 

 satus Osten Sacken must also somewhat resemble this. The 

 convexity of the thorax, which is " Kaputzenartig " resembles 

 very much that of Pseudorus bicolor Bellardi as figured by 

 Bellardi, and is seen in less degree in our species of Holocephala. 

 The face in profile is gently convex from the antennae to the 

 oral margin, but is most projecting below. The species is 

 very thinly pilose." 



? Cyrtopogon nebulo (PI. IX, fig. 1.) 



Cyrtopogon nebulo Osten Sacken, West. Dipt., 309, 1877. 

 Cyrtopogon nebulo Williston, Tr. Am. Ent. Soc, XI, 14, 1884. 



" 9 — Length 8-9 mm. — Gray; thorax with a geminate brown stripe; 

 abdomen polished, black, with white spots in the hind corners of seg- 

 ments 1-5; wings with brown clouds on the cross- veins and on the 

 furcation of the third vein. 



"Face and front grayish pruinose, with black hairs; the hairs on 

 the face, in a certain light, look whitish at the tip; occiput with white 

 hairs. Antennae black. Thorax grayish pruinose, with brown stripes; 

 the intermediate one dark brown, geminate, abbreviated before reach- 

 ing the scutellum, but coming in contact with a pair of elongated 

 brown spots in front of the scutellum; scutellum convex, with rather 

 dense, long and soft white hair, and some blackish bristles along the 

 hind edge; pleurae with whitish pile. Halteres with a dark brown 

 knob. Abdomen black, polished, with white hair on the sides; seg- 

 ments 1-5 in the hind corners with a spot of white bloom of moderate 

 size. Legs black, beset with long white hairs; most of the spines are 

 also whitish, especially toward the tip, the roots being often brownish. 

 Wings hyaline, with black veins; central cross- veins, those at the 

 distal end of the discal cell, the small cross- vein and the bifurcation of 

 the third vein are very distinctly clouded with brown." 



Type.— M. C. Z. A single female. 



Habitat.— Webber Lake, Sierra Co., Cal. (0. S., July 22, 

 1876); Wash. (Wilst) ; Coldstream Ranch, Vernon, B. C. (Miss 

 Ricardo, May 22, 1902). 



The specimen from British Columbia is a female in the col- 

 lection of the Massachusetts Agricultural College. As it agrees 

 perfectly with the type specimen, I have made it a homotype. 

 Dr. Williston states that two specimens from Washington 

 have the antennal style a trifle shorter than the third segment. 



