10 THE CANADIAN ENTOMOLOGIST 



8. All femora largely fuscous; hind tibia with one strong and sometimes one 



weak anteroventral bristle; prealar bristle minute; wings not yellow 



at bases obscura Stein. 



At most the fore and mid femora infuscated; wings yellow at bases, or 

 dorsum of thorax indistinctly vittate 9. 



9. Small species, 5.5 to 6.5 mm. in length; thorax and abdomen with dis- 



tinct but not very dense pruinescence, the former distinctly vittate 

 only in front; prealar bristle very small winnemanna Malloch. 



Larger species, 7 to 9 mm. in length; thorax and abdomen with dense 



yellowish pruinescence, the former with very distinct vitta' 10. 



10. Fore femora yellow; second antennal segment brown; prealar bristle one- 

 third as long as the one behind it discimana Malloch. 



Fore femora infuscated; second antennal segment black; prealar bristle 

 over half as long as the one behind it iirbana Meigen. 



FEMALES. 



1. All femora largely or entirely black 2. 



Femora reddish yellow, sometimes the fore pair brownish or fuscous in 



part 6. 



2. Eyes distinctly hairy • calvicrura Coquillett. 



Eyes bare '■■• 3. 



3. Arista with its longest hairs not longer than its basal diameter. rMgm Walker. 

 Arista with its longest hairs as long as or longer than width of third antennal 



segment 4. 



4. Third antennal segment distinctly less than 4 times as long as its greatest 



width; mid and hind femora entirely or almost entirely black or 



fuscous 5. 



Third antennal segment at least 4 times as long as its greatest width; 

 mid and hind femora, and especially the latter very indistinctly 

 infuscated winnemanna Malloch. 



5. Calyptra? white; tibiie yellowish testaceous obscura Stein. 



Calyptra^ orange yellow; legs entirely black obscurella Malloch. 



6. Scutellum largely or entirely yellow, contrasting sharply with the disc of 



mesonotum 7. 



Scutellum black, concolorous with disc of mesonotum 9. 



7. Palpi and antennae yellow^ , Jiavicornis Coquillett 



Palpi entirely, antennae largely black 8. 



8. Humeral angles of thorax broadly yellow occidentalis Malloch. 



Humeral angles of thorax coloured as disc pagana Fabricius. 



9. Apical segment of fore tarsus disclike, as broad as lohg; fore tibia with a 



median posterior bristle discimana Malloch. 



Apical segment of fore tarsus normal, about twice as long as wide 10. 



10. Arista densely short-haired, the longest hairs barely as long as its basal 

 diameter; fore tibia with 1 posterior and 1 postero-ventral 

 bristle armatipes n. n. {armipes Malloch nee. Stein). 



Arista with long hairs, the longest of which are at least as long as width 

 of third antennal segment, or the fore tibia with or without one 

 bristle 11. 



