1909] Rohherflies of the Genus Asihis 147 



Asilus avidus Van der Wulp (Fig. 6). 



General color reddish gray, abdomen darkest and with prominent 

 gray margins to each of the segments above; eighth ventral segment 

 of the male slightly produced posteriorly but with only a few bristly 

 hairs on its margin. Preapical band and usually the posterior side 

 of each femur and the tibiae and tarsi dark reddish. Length 15-18 

 millimeters. 



Facial gibbosity rather prominent. With black bristles above and 

 yellowish gray bristles below; each antenna black, third segment exclu- 

 sive of the arista scarcely as long as the other two, arista hardly as 

 long as the third segment; beard white; occipito-orbital bristles yel- 

 lowish gray with the exception of three to five black bristles behind the 

 upper part of each eye. Thorax gray with the usual dark markings 

 above, bristles of the posterior part prominent and black, about four 

 black bristles on the margin of the scutellum. Legs clothed with 

 fine hair and prominent bristles; the hair is either white or yellowish 

 but the bristles are black; each coxa and the anterior side of its femur 

 black, otherwise each leg is reddish, slightly darker in some places 

 than in others. Wing hyaline with a slightly darkened tinge at the 

 apex. Abdomen rather dark but appearing yellowish gray from cer- 

 tain angles; narrow posterior margin of each segment plainly gray, 

 margin of the eighth segment below in the male plainly produced and 

 forming a distinct angle but not with so prominent a tuft of hairs as 

 in occidentalis. 



Several specimens from Copeland Park and North Boulder Creek, 

 near Boulder, Colorado, the latter part of August and the first part of 

 September, 1907. Collected by S. A. Rohwer and Glen M. Hite. Also 

 from Beula, New Mexico, 8000 feet elevation, by Cockerell. 



Everything considered this is most like Van der Wulp's species. 

 The tibiae are most plainly red at base but nowhere is there a sharp 

 differentiation of colors as in most specimens of occidentalis. The 

 male genitalia are nearly straight, and in this respect quite different 

 from those of occidentalis. The latter character more than any 

 other has led to the determination of this species as avidus. 



Asilus occidentalis n. sp. (Fig. 7). 



General color gray with the thorax often yellowish gray. In some 

 specimens each femur has a preapical reddish band, in others this is 

 not the case. Posterior margin of the venter of the male eighth ab- 

 dominal segment furnished with a dense cluster of rather long bristly 

 hairs. Length 14-18 millimeters. 



Facial gibbosity prominent, mystax largely black but with a num- 

 ber of yellowish hairs below; face clothed with yellowish dust,- beard 

 white; each antenna black with the third segment exclusive of the 

 arista slightly longer than the first two segments together, arista 

 scarcely as long as the third segment. Occipito-orbital bristles mostly 

 black, but in some specimens nearly all yellow. Thorax grav or yel- 

 lowish gray, median darker markings not especially prominent, scutel- 

 lum with at least four bristles on its margin. Legs dark, each femur 



