262 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



sides the long black pile, in some specimens sbows some shorter, yel- 

 low hairs. The whole under side of the body as well as the three 

 last abdominal segaients above are beset with deep black pile, which 

 forms a dense fringe on the edge of those segments, especially long, and 

 consisting of a row of tufts in the male. The upper side of the thorax, 

 as well as the whole anterior half of the dorsal side of the abdomen, is 

 clothed with pale. yellow (straw-colored) pile. The ground-color of the 

 thorax is black ; that of the abdomen greenish-blue, shining, except the 

 first segment, which is opaque, blackish ; wings grayish-hyaline, brown 

 at base and along the anterior margin as far as the end or' the first vein, 

 the brown gradually evanescent posteriorly^ halteres black; leg black. 

 Length 9-10°^'". 



Rob. — Yosemite Valley, California, where I caught two females and 

 one male of this pretty species, June 5-15. 



7. Ploas n. sp., 9 . — I have a single specimen from Yosemite Valley, 

 June 14, measuring ^-Q'^m without the antennae: knob of hal teres black, 

 except the base, which, like the stem, is yellow ; first joint of the an- 

 tennae unusually long and stout, the second cylindrical, about one-third 

 as long as the first. The specimen being denuded is unfit for a de- 

 scription. The body is uniformly black; tufts of yellow pile are left 

 on the sides of the thorax. I mention this species in order to call the 

 attention of collectors to it. 



Pakacosmus 



(nomen novum, vice Allocotns Loew). 



Paeacosmus edwardsi Loew, Centur,, x, 48 {Allocotus). — The name 

 given by Mr. Loew to this new genus being pre-occupied {Allocotus Mayr, 

 Hemipt., 1864; Allocota Motchulski, Coleopt., 1859), I have changed it to 

 Paracosmus (meaning, in Greek, disorderly). 



Loew describes the female. In the male, the eyes are not contiguous 

 on the front, which is but little narrower than that of the female. The 

 eyes have uniform facets above and below. The hypopygium is rather 

 large for the family, consisting of subhemispherical lower piece and a 

 forceps-like organ above,- with broad valves. 



I found this curious insect in both sexes, flying in the sun over the 

 sands round Lone Mountain, San Francisco, June 29. 



Phthiria. 



I do not possess P. punctipe^mis Walker (List, iii, 294) from Geor- 

 gia. P. sulphiirea seems to have a wide distribution, from Kew Jersey 

 to Colorado and Texas. The other species seem to be more exclusively 

 western or Californian. 



1. Phthiria sulphurea Loew, Centur., iii, 18 (Xew Jersey, female). — 

 I have specimens from Waco, Texas (Belfrage, communicated by Mr. 

 Burgess), Colorado Springs (Uhler), and Illinois (Le Baron), whi3h ap- 



