124 Bulletin of the Brooklyn Entomological Society Vol. XV 



sents the appearance of an overlapping scale ; fifth 

 sternite with rather conspicuous black hairs in a series 

 near inner margin on basal half of each process which 

 give the sternite the appearance of having a black 

 fringe on each side of incision ruficeps Stein 



— Third antennal segment with but slight indications of the 



pale scale like mark on inner side at base ; fifth sternite 

 with a few inconspicuous dark hairs, .rufescens Stein 

 i6. Mid femur with a very strong bristle on anteroventral 

 surface at or beyond middle ; costal setulae much 

 longer than diameter of costal vein 17 



— Mid femur without such bristles ; costal setulae very 



weak 18 



17. Cheek much higher than length of third antennal seg- 



ment ; hind femur with a regular series of 6 or 7 

 widely spaced anteroventral bristles. 



spinosissima Stein 



— Cheek barely higher than length of third antennal seg- 



ment; hind femur with 2 or 3 bristles on basal half 

 and 2 or 3 on apical half of anteroventral surface, with 

 a rather wide space between the series. 



spinigerellus Malloch 



18. Arista with dense pubescence, its longest hairs at least 



as long as its basal diameter ; third antennal segment 

 largely yellowish gopheri Johnson 



— Arista with barely distinguishable pubescence 19 



19. Third antennal segment largely yellowish ; mid tibia with 



a median anteroventral bristle finitima Stein 



— Third antennal segment generally deep black ; mid tibia 



without a median anteroventral bristle . . . affinis Stein 



20. Thorax reddish testaceous, with a fuscous dorsocentral 



vitta ; hind tibia with a posterior bristle one third from 

 base lahradorensis Malloch 



— Thorax black ; hind tibia without a posterior bristle . . 21 



21. Thorax w;hen seen from above and behind with a broad, 



deep black shining vitta on each side ; palpi entirely 

 black 22 



— Thorax sometimes more or less distinctly vittate but not 



as above 24 



22. Longest hairs on arista as long as width of third antennal 



segment ; fifth sternite with dense brushlike fringe of 

 stiff, short, black setulae on basal half of inner margin 

 of each process juvenilis Stein 



— Longest hairs on arista not nearly as long as width of 



third antennal segment ; fifth sternite not as above . 23 



