254 THE CANADIAN ENTOMOLOGIST 



downwardly directed and slightly curved; the segment before it glossy, 



with 3 long bristly hairs on each side of disc arctica Malloch. 



Basal segment of hypopygium either with short hairs or bristles on sides 

 or with slender bristly hairs, or the segment in front of it is highly glossy 

 and bare, or pruinose and sparsely hairy 4. 



4. Segment in front of basal hypopygial glossy, bare; hind tibia with 4 postero- 



dorsal bristles polita Malloch . 



Segment in front of basal hypopygial more or less pruinescent and with 

 numerous bristly hairs 5. 



5. Upper calyptra dark-haired at lateral angle; bristles on abdominal tergites 



most dense and stronger on the portions incurved 



ventrad katmaiensis Malloch . 



Calyptrae entirely pale-haired; bristles on tergites strongest at apices on 

 dorsum 6. 



6. Mid femur with 3 or 4 short, strong bristles on basal half of anteroventral 



surface; hind tibia with 3 posterodorsal bristles occidentalis Malloch. 



Mid femur without bristles on basal half of antero\'entral surface; hind 

 tibia with 2 posterodorsal bristles 7. 



7. Eyes separated by more than width across posterior ocelli; mid tibia with 



a small, anteroventral bristle; processes of fifth abdominal sternite 

 moderately stout, with very minute hairs on their apical halves, and 

 a sparse fringe of hairs on their inner margins on basal 



half proxima Malloch . 



Eyes separated by less than width across posterior ocelli; mid tibia with- 

 out an anteroventral bristle; processes of fifth abdominal sternite slender, 

 with long hairs to apices, their inner margins with a fringe of closely- 

 placed, rather long hairs on basal half divisa Meigen. 



8. Fourth tergite (third visible) without a dense tuft of fuscous bristly hairs, 



which are backwardly directed, at each posterior lateral angle 9. 



Fourth tergite with a tuft of fuscous bristles or hairs at each posterior 



lateral angle 13. 



9. Abdomen with sides of second and third tergites largeh' yellowish testa- 



ceous; legs brownish, not deep black; arista with its longest hairs about 

 as long as width of third antennal segment subpelliicens Malloch. 



Abdomen and legs entirely black; longest hairs on arista not as long as 



width of third antennal segment 10. 



10. Hind tibia with a few bristly hairs on posterior surface basad of 



middle 10 a. 



Hind tibia without bristly hairs on posterior surface; hypopygium with 



strongest bristles at or near its base 11- 



10a. Narrowest part of frons not wider than distance between posterior ocelli; 

 process of fifth sternite elongate, subcylindrical, their inner margins 

 with a few fine hairs, their outer margins with some long 

 bristles '. galeata Malloch. 



Narrowest part of frons as wide as distance across posterior ocelli; process 

 of fifth sternite short, broad, glossy, their inner margins fringed with 

 long, fine hairs, their outer margins bare seticaiida Malloch. 



