THE CANADIAN ENTOMOLOGIST 63 



abdomen with paired dorsal spots which are sornetimes fused or 

 without distinct spots, and never with a dorsocentral vitta 14. 



14. Calyptrae exceptionally small, the lower one not twice as large as the upper; 



abdomen with the dorsal spots so greatly enlarged as to cover the 

 entire dorsum except the extreme posterior margin of each tergite; 

 costal hairs setulose, very distinctly longer than diameter of costal 

 vein; vibrissa! angle not noticeably produced beyond line of base of 

 antennae obsoleta Malloch. 



— Calyptrae large, the lower one twice as large as the upper; abdomen with 



distinct paired dorsal spots; costal setulae minute; if the abdomen is 

 indistinctly spotted the vibrissa! angle is produced much beyond a 

 vertical line drawn from base of antennae 15. 



15. \'ibrissal angle but little produced, almost in vertical line with base of 



antennae 16. 



- — Vibrissa! angle very conspicuously produced beyond vertical line from 

 base of antennae 17. 



16. Small species, not 4 mm. in length; abdomen unspotted, the entire l^cdy 



with whitish pruinescence; genitalia with 4 short 



thorns hrevicornis Malloch . 



- — Larger species at least 5 mm. in length; abdomen with large blaclc paired 

 spots, the entire body with brownish pruinescence nobilis Stein. 



17. Hind femur with 4 or 5 moderately stout, long bristles on apical two-fifths 



of anteroventral surface; last section of fourth vein three times as 

 long as preceding section ; veins 2 and 4 up to outer cross- vein and both 



cross-veins tinged with brown along their courses pearyi Malloch. 



Hind femur with long, hair-like bristles from base to apex on antero- 

 ventral surface; last section of fourth vein less than twice as long as 

 preceding section; veins not tinged wnth brown 18, 



18. Large species, at least 6 mm. in length; female orbits with rather dense 



bristly hairs laterad of the bristles, the hairs almost as long as the 

 bristles; wnngs of male rather pointed at apices angnlala Malloch. 



— Smaller species, not over 4.75 mm. in length; female with short sparse 



hairs laterad of the bristles on orbits; wings of male rounded at 

 apices extensa Malloch. 



19. Calyptrae dark brown; wings distinctly infuscated; eyes of male separated 



by much less than width across posterior ocelli anthrax Bigot. 



— Calyptrae whitish; halteres yellow; wings usually clear 20. 



20. Eyes separated by almost one-third of the head-width; hind femur without 



posteroventral bristles; the paired dorsal abdominal spots with a 

 connecting brown pa.tch between them caroli Malloch. 



— Eyes separated by much less than one-third of the head-width; abdominal 



dorsal spots not as above 21. 



21. Hind tibia with one or more setulae at or near middle on posterodorsal 



surface : 22. 



— Hind tibia without setulae on posterodorsal surface 27. 



22. Tibia? pale, reddish; wings clear, veins pale; abdomen narrow, c>lindrical, 



the dorsal spots of moderate size, widely separated; fore tibia with a 

 median posterior bristle suspecta Malloch. 



