OSTEN SACKEN ON WESTERN" DIPTERA. 211 



Female. — Autennoe but little longer than the head ; joints of flagellum 

 slightly iucrassate at base ; the whole body more opaque than that of 

 the male ; hence the velvety cross-bands on abdomen less apparent ; ovi- 

 l^ositor ferruginous-brown (valves divaricate in the dry specimens). 



Sab. — Rocky Mountains, at great altitudes ; male specimens were found 

 July 15, 1875, on Taos Peak, IsTew Mexico, above timber-line (W. L. Car- 

 penter); females on Pike's Peak, July 14, 1875, at 13,000 feet altitude 

 (A. S. Packard). Three males and as many females. 



Pachyerhina ferruginea Fabr. — A very common eastern species. 

 I have a male and a female from California (San Mateo) and two males 

 from Denver, Colo. (P. E. Uhler), which have no black or brown trian- 

 gles on the abdomen. It seems, nevertheless, to be the same species. 



HoLORUSiA RUBiGiNOSA Locw, Ccntur., iv, 1. — ]S"ot rare in Marin 

 and Sonoma Counties in May. 



Ctenophora angustipennis Loew, Centur., x, 3. — Not rare among 

 the red- woods in the Coast Range. The larva prqbably lives in the stumps 

 of Sequoia semj^ervirens. (Lagunitas Creek, Marin County, April 15; 

 also numerous specimens from Mr. H. Edwards.) 



Family BIBIONID^. 



BiBio HiRTUS Loew, Centur., iv^, 2; <? 9 . — ^Marin and Sonoma Coun- 

 ties, California, in April, common ; Yosemite Valley, June 1-12. Mr. 

 Loew's description implies that this species is very variable, and indeed 

 I have male specimens, from the same localities, which look like a dif- 

 ferent species ; they are almost destitute of whitish hairs, showing only 

 a few of them on the sides of the abdomen ; the size of the specimens 

 is also variable. 



BiBio NERVOSUS Loew, Centur., iv, 4 ; 2 . — California. I did not come 

 across this species. 



BiBio sp., $ 2 . — (Saucelito, April 2 ; San Geronimo, Marin County, 

 April 19.) A red-legged species, like the preceding, but different. 



DiLOPHUS sp., $ $ . — Marin and Sonoma, in April, common. 



• ' Family XYLOPHAGID.E. 



Rachicerus hokestus n. sp. — Antennae 22-23-jointed, moniliform, 

 subpectinate ; thorax brownish-yellow, with ,two brown stripes ; abdo- 

 men dark brown ; wings tinged with brownish. Length 5.5™"\ 



Male. — Itead and antennae black; palpi yellow; front above the anten- 

 nae with a silvery cross-band; antennae 22-jointed, if the last joint, 

 which is double, is counted for one ; they are moniliform and subpecti- 

 nate on both sides, the projections on the lower side being a little longer 

 than those on the upper. Thorax brownish-yellow, with two broad 

 brown stripes, which begin a little behind the humerus and do not 

 touch the anterior margin ; pleurae brown. Abdomen uniformly dark 

 brown, with a delicate grayish-yellow pubescence. Legs, including the 



