290 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



bristles, not only on the tibiae, but also on the upper side of the front 

 and hind femora; ungues remarkably long, and no vestige of pulvilli ; 

 the two last joints of the front tarsi in A. mimus are ornamented with a 

 dense brush of short bristles. 



Wings like those of Cyrtopogon ; all posterior cells open ; anal cell 

 with a narrow opening ; small cross- vein a little beyond the middle of 

 the discal cell. 



1. Ablautatus trifakius Loew, Centur,, vii, 63, female (Cali- 

 fornia). 



2. Ablautatus mimus n. sp., ^ 5. — General coloring brownish- 

 gray, with a series of rounded blackish spots along the middle of the 

 abdomen, one at the base of each segment ; larger black spots in the 

 anterior corners of the same segments form two lateral series; segments 

 7 and 8 in the male black, shining, beset with white pile ; segment 7 

 in the female black, shining. Thorax gray, with the usual three darker 

 stripes. Legs black, densely beset with rather long, recumbent white 

 hairs, and long, white, erect bristles; ungues black. The two last joints 

 of the front tarsi in the male appear incrassated, because they are 

 densely beset with black and yellow, recumbent, and closely packed 

 short bristles, forming a kind of brush, the end of which reaches consid- 

 erably beyond the ungues ; the under side of this brush is black, on its 

 upper side it is mixed of black and yellow ; the ends of the first three 

 joints of the front tarsi are armed with strong bristles, or spines, which 

 are black, with a yellowish root ; a couple of such spines in the middle 

 of the first joint. In the female, the front tarsi are simple, and ail the 

 spines upon them are white, like all the other spines on the legs. Hal- 

 teres honey -yellow. Antennse black, the spines on the under side of the 

 first two joints brownish-yellow. Fan-like fringe of hair in front of the 

 halteres white. Mystax white, a few black bristles above the mouth ; 

 occiput with white pile. Wings very hyaline; veins black. Length 



Y Qmm 



Hah. — Crafton, near San Bernardino, Southern California, in March. 



OSPRIOCBRUS. 



1. OSPEIOCERUS ^Acus Wied., i, 390 (syn. Basypogon abdonii- 

 nalis Say). — Not rare about Colorado Springs, Colo. (P. E. Uhler). 

 Wiedemann's description agrees with the female ; in the male, the sixth 

 and seventh abdominal segments are red ; the hypopygium black. I 

 also have two males from Spanish Peaks, Colo., June 15 (W. L. Carpen- 

 ter), which agree with the others. 



2. OsPRiocERUS EUTROPHUS Locw, Berl. Ent. Zeit., 1874, 355, 

 female (Texas). — I have seen two females from Kansas (G. F. Gaumer), 

 which belong here; one of them had the thoracic dorsum reddish, a 

 variety which Dr. Loew mentions as occurring in 0. rhadamantMis. 



3. OSPRIOCERUS RHADAMANTHUS Loew., Ccntur., vii, 52, male (Pe- 



