1909] Robberfiies of the Genus Asilus 161 



Asilus prairiensis Tucker. 



A light brown species, preapical band and the posterior side of 

 each femur brown. Front femur with close lying hair and several 

 distinct bristles in a longitudinal row on the under side. Length 14-20 

 millimeters. 



Mystax yellow with the exception of a very few short black hairs 

 above, occipito-orbital bristles yellow, as are most all of the bristles of 

 the whole body ; third segment of the antenna long, nearly twice the 

 length of its arista. Anterior femur with a red preapical band and 

 posterior surface, otherwise black; tibia dark at the middle, especially 

 on the anterior side and at the apex ; metatarsus nearly entirely red, 

 other tarsal segments mostly black ; middle leg like the front one ; hind 

 leg the same except the dark color of the tibia is more suffused. Wing 

 with the apex and the posterior margin faintly clouded, otherwise 

 hyaline. In some specimens the hyaline tends to follow the margins 

 of the veins into the clouded area. Abdomen yellowish brown, the 

 gray posterior margins of the segments not ver}^ plainly marked. 



Specimens are at hand from Kansas, Colorado, New Mexico and 

 Texas. 



This species in the southern states appears to occupy about the 

 same position as paropus at the North. Macquart's description of 

 annulipes from Carolina does not apply well to any of the robber-flies 

 known to me from the northern states, especially is this true of the 

 words "Cuisses fauves, brunatres en dehors," but does apply to 

 the present species. These is an older Asilus annulipes by Brulle 

 from Europe, so the name is not tenable for the American insect. 

 With a large series of specimens before me showing quite a range in 

 size and to some extent in coloration, the conclusion is reached that 

 Tolmerus prairiensis Tucker is the same and being the name next 

 available becomes the name of the species. 



Asilus paropus Walker. 



A medium sized species, femora entirely black with the exception of 

 a reddish preapical ring; Wing reddish although hyaline along the 

 veins of the disk and the base. Front femur with distinct bristles 

 below. Length 13-17 millimeters. 



Facial gibbosity prominent, mystax composed of numerous bristly 

 hairs which are mostly pale but there are a very few black ones 

 above. Antennae black, or at most only narrowly yellow at the apex 

 of the second and the base of the third segments; occipito-orbital 

 bristles in large part yellow but variable; in a pair taken in couple, 

 these bristles are black in the female and yellow in the other sex. 

 Thorax thinly clothed with yellowish dust and with the usual markings 

 above, short black hairs anteriorly and long black bristles posteriorly. 

 Wings distinctly reddish, most of the veins of the disk and toward the 

 base plainly margined with hyaline. Front leg with the femur, except 

 a preapical band, middle and apex of the tibia, narrow apex of the 

 metatarsus and all except the extreme bases of the other tarsal seg- 

 ments black or infuscated, otherwise yellowish; middle leg like the 



