1909] Robber flies of the Genus Asilus 149 



Asilus piceus n. sp. (Figs. 10 and 11). 



Nearly black species with hyaline wings and brown legs. Length 

 15 to 17 millimeters. 



Facial gibbosity not very prominent, reaching half way to the 

 antennae, mystax composed of black and white hairs, intermixed, 

 beard white, occipito-orbital bristles largely black, face and front 

 clothed with gray dust, antennae black, third segment exclusive of the 

 arista near the length of the other two, arista equal to the third seg- 

 ment in length. Thorax brown in ground color, clothed with gray 

 or yellowish gray dust, mid-dorsal stripe rather wide, black, split on 

 the anterior part and abbreviated behind ; wings clear hyaline in both 

 sexes, veins brown ; legs brown with light colored hairs and with light 

 and dark bristles. Coxae colored like the thorax, anterior sides of 

 all the femora, apexes of all the tibiae and the last four segments of 

 each tarsus darkened more or less. Abdomen black, posterior margins 

 of the segments narrowly gray, male forceps distinctly excavated at 

 the upper corner of the apex, first segment of the oviduct nearlv as 

 long as abdominal segments five, six and seven; apical segment style- 

 like and near the length of abdominal segment seven. 



Specimens from Amherst, Massachusetts, from the collection of 

 the Massachusetts Agricultural College. 



Asilus montanus n. sp. (Figs. 12 and 13). 



Rather small, slender, gray species with hyaline wings, largely 

 reddish legs, very small facial gibbosity and mystax composed of a 

 few bristly hairs which are mostly white, although there are a few 

 black ones above. Length 13 millimeters. 



Face clothed with gray dust; palpi and proboscis black, the former 

 with white hairs; occipito-orbital row of bristles with a few black 

 ones back of each eye, otherwise all the bristles and hairs of the occi- 

 put white. Thorax gray, mid-dorsal stripe black, divided before and 

 abbreviated behind; several black bristles on the posterior part, two 

 black bristles on the margin of the scutellum. Wings clear hyaline; 

 legs reddish, anterior side of each femur, apex of each tibia and each 

 tarsal segment fuscous. Abdomen clothed with grayish dust, most 

 pronounced on the posterior margins of the segments. These margins 

 are preceded on each side by two or three small bristles. Forceps of 

 the male shining brownish black, each upper with a distinct angle on 

 the dorsal side at about four fifths of the length. 



This species is entirely distinct from its relatives on account of its 

 small facial gibbosity and the few bristles composing the m3rstax. 

 The male genitalia are distinctive also. 



A male collected by Cockerell at Alpine Tavern, Mount Lowe, 

 California, at an altitude of 5,000 feet. Taken August 12th. Tvpe 

 in the United States National Museum. 



