THE CANADIAN ENTOMOLOC'rIST 107 



30. Hind tibiae with rather dense long bristly hairs on ventral surfaces. . . .30a. 



— Hind tibia without dense bristly hairs on ventral surfaces 30b. 



30a. Hind femur with some long bristly hairs on apical half of posteroventral 



surface; cross-veins indistinctly infuscated oregoncnsis Malloch 



— Hind femur without long bristly hairs on posteroventral surface; cross- 



veins very conspicuously infuscated cothurnata Rondani. 



30b. Only the fore femora blackened; palpi yellow; prealar bristle absent; cross- 

 veins not infuscated; hind femur bare at middle on posteroventral sur- 

 face abiens Stein 



— All femora more or less blackened; palpi largely or entirely black; prealar 



bristle distinct except in spuria 31. 



31. Cross-veins of wings very conspicuously infuscated; hind femur bare at 



middle on posteroventral surface ; third vein bare at base ; basal abdom- 

 inal sternite setulose obscurinervis Stein 



 — Cross-veins of wings very narrowly infuscated ; hind femur with a few 

 short bristles on middle of posteroventral surface; third wing-vein at 

 base and basal abdominal sternite bare spuria Malloch 



— Cross-veins of wings not infuscated ; hind femur with two or three short 



bristles at middle of posteroventral surface; third vein with a few 

 weak setulae at base above and below ; basal abdominal sternite 

 bare Xenomydaca buccata Malloch 



FEMALES. 



1. Hypopleura with some fine hairs below spiracle 2. 



— Hypopleura with some hairs on its upper margin in front of 



spiracle marmorata Meigen ? 



— Hypopleura bare 5. 



2. Hind tibia with three anterodorsal bristles ; wing-veins 3 and 4 very decided- 



ly divergent at apices multi?^etosa Schnabl 



Hind tibia with two anterodorsal bristles; veins 3 and 4 very little divergent 

 at apices 3., 



3. Thoracic and abdominal pruinescence brownish gray ; calyptrae yellow- 



ish lucoruni Fallen 



white ^ punctata Stein 



— Thoracic and abdominal pruinescence whitish gray ; calyptrae 



4. Legs entirely black, rarely with the knees reddish 6. 



— Legs with at least the tibiae of one or more pairs reddish or yellowish. . . . 



5. Mid tibia with one or more anterodorsal bristles ; hind tibia with one or 



two posterodorsal setulae near base 7. 



— Mid tibia without anterodorsal bristles ; or the hind tibia has no postero- 



dorsal setulae near base and the arista is nearly bare 9. 



6. \'entral surface of scutellum with soft erect hairs. . . .hylemyioides Malloch 



— X'entral surface of scutellum bare 7. 



7. Halteres blackish brown nitida Stein. 



• — Halteres pale yellow latifrontata Malloch 



8. Halteres black 9, 



— Halteres pale 10 



