230 BULLETIN 116, UNITED STATES NATIONAL MUSEUM. 



Type location. — ^Little Wind River, Wyoming, September 2, 1895; 

 and Natrona Coimty, Wyoming, Angust 31, 1895, taken by Dr. W. M. 

 Wlieelcr. 



The only characters to separate this from ciliatus, as far as I can 

 make out, are tiie violet front, the glabrous streak on posterior face, and 

 possibly the less infuscated tip to the hind tibiae. The cilia of the 

 calypters may be less dense and shorter, but I can not tell from the 

 type. 



The preceding group of seven species, although differing widely 

 in some cases, have several striking characters in common. These 

 forms are idahoensis Aldrich; cavatus, new species; afflidus Osten 

 Sacken; crenatus Osten Sacken; aurifex, new species; consanguineus 

 Wlieeler, and hruesi Van Duzee. The characters which these have in 

 common are: Fore coxae yellow, with a peculiar black or green 

 stripe on outer edge of the posterior surface, which reaches nearly 

 their entire length, and is rather wide above, tapering to a point 

 below, rarely the green is more extensive. Fore tarsi plain, about as 

 long as their tibia, with the first joint nearly as long as the remaining 

 four joints taken together; fourth joint slightly shorter than any of 

 the others; fore tarsi infuscated from the tip of the first joint. Fore 

 and middle trochanters with a brown dot, hind ones wholly brown. 

 Hind femora without cilia below, but with a row of bristles of increas- 

 ing length, ending in the usual preapical bristle. Middle tibiae with 

 two large bristles below, their basitarsi without a bristle above. 

 Hind tibiae a little thickened and compressed and with a shallow 

 groove on inner surface, which appears to be glabrous. Wings with 

 the costa more or less thickened at tip of first vein. 



Of the characters that separate the species the most striking is 

 the form of antennae. In all but the two first the first joint is long 

 and furnished with long stiff hairs or bristles, being typical of the group 

 which was included in the genus Hygroceleuthus; the first three have 

 the antennae of the usual form, typical of the genus DolicJiopus as it 

 used to be restricted; of the two first cavatus has the cilia of the 

 calypters black, while in idahoensis they are pale. Affiictus is easily 

 separated from the remaining five species by the tufts of long yellow 

 hair on the sides of the second abdominal segment. Of the remaining 

 four forms the cilia of the calypters are pale in the male of crenatus, 

 black in the others. Of these three species hruesi has the orbital cilia 

 wholly black; in consanguineus there are from four to ten orange- 

 colored cilia on the side with black cilia above and below; while in 

 aurifex the lower orbital cilia are pale yellow. The form of the wings 

 also furnish good characters for separating these species. 



