1909] Robberflics of the Genus Asilus 143 



22. Dorsum of the thorax for its entire length with a crest of long 



hairs coquillettii n. sp. 



Dorsum of the thorax with the hairs on the anterior part distinctly 



shorter than on the posterior part brevicomus n. sp. 



23. From dorsal view male forceps wider at two thirds their length than 



at their base. First segment of the female ovipositor, that is, the 

 eighth abdominal seginent longer than the sixth and seventh 

 united 24. 



From dorsal view male forceps gradually narrowed from near the 

 base to the apex. First segment of the female ovipositor of nor- 

 mal length, not so long as the sixth and seventh segments united . .31. 



24. Male forceps distinctly wider than the abdoinen at the middle of its 



length 25. 



Male forceps not wider than the abdomen at the middle of its length . . 26. 



25. Wings narrow, male genitalia more than two millimeters in width 



at the apex angustipennis n. sp. 



Wings wide, male genitalia less than two millimeters in width at 



the apex latipennis n. sp. 



26. Mystax golden, usually with a few black bristles above. Preapical 



bristles of the abdominal segments pale yellow, male wings not 



distinctly brown at middle auricomus n. sp. 



Mystax gray with some bristles above, or if the mystax is not gray, 

 the wings of the male are distinctly brown at middle, preapical 

 bristles of the abdominal segments gray 27. 



27. Wing of the inale distinctly brown at the middle of the length 28. 



Wing in both sexes hyaline, or very faintly tinged with reddish all over29. 



28. General color black. Viewed from above the male genitalia on each 



side evenly curved to the apex lepidus n. sp. 



General color brown. Viewed from above the male genitalia on 



each side quite suddenly contracted just before the apex 



willistoni n. name. 



29. Facial gibbosity small, not reaching half way to the antennae, wings 



hyaline montanus n. sp. 



Facial gibbosity large, reaching more than half way to the antennae . . 30. 



30. Body gray, legs red, wings faintly tinged with reddish, bristles and 



hairs of the body white albicomus n. sp. 



Body black, legs dark, wings very faintly smoky, bristles of the 



thorax and legs mostly black piceus n. sp. 



31. Wings clear hyaline, rather large species, upper forceps of the male 



genitalia split at the tip californicus n. sp. 



Wings washed or spotted with gray at the apex and along the poster- 

 ior border, species of variable sizes, upper forceps of the male 

 genitalia entire at the ajjex 32. 



32. Very small species; antennal arista very short, not over one fourth 



the length of the third segment and not distinctly differentiated 



from this segment mesae Tucker. 



Larger species, antennal arista distinctly differentiated from its 

 segment 33. 



33. Arista of the antenna about as long as the third segment, only. two 



bristles in addition to the apical bristles on the front side of the 

 hind tibia. These bristles are not entirely uniform but may be 



depended upon usually 34. 



Arista of the antenna ustially not over two thirds as long as the 

 third segment, three bristles on the front side of the hind tibia. . . .44. 



