198 THE CANADIAN ENTOMOLOGIST. 



8. — Front of female partly shining black 9 



Front in both sexes wholly opaque and covered with pollen n 



9. — Abdomen of female opaque on the first six segments, front with 



two shining black spots Johnsonii, n. sp. 



Abdomen of female largely shining 10 



10. — Front of female with a shining black spot reaching the lower 

 ocellus ; pollen on sides of front extending less than half way . 



from each eye to lower ocellus strigipes, Loew. 



Front of female having the lower half shining, the upper half 



covered with pollen . hirticeps, Loew. 



Front of female wholly shining black, except each lower corner 



nigra, Say. 



Front of female with only one shining black spot ; pollen on sides 

 of front nearly or quite reaching the lower ocellus . .frontalis, Say. 



n. — Pile of front largely black 13 



Pile of front wholly white, front of female destitute of large, 



velvet-black spots = 12 



12. — Bristles of occiput black, eighth abdominal segment in the female 



shining black, stigma dark brown albifrons, Say. 



Bristles of occiput whitish, eighth segment in the female covered 



with pollen, stigma pale yellow novella, n. sp. 



13. — Wings hyaline, the cross-veins not broadly bordered with brown. . 14 

 Wings brownish, the cross-veins broadly bordered with darker 



brown comata, Loew. 



14. — Third joint of antennae unusually short, inverted pyriform, the 



first joint very robust melanophleba, Loew. 



Third joint of antennae not unusally short melanoneura, Loew. 



Thcreva sanitaria, n. sp. $ black, the antennas, palpi, knob of the 

 halteres, posterior margins of the second and third abdominal segments, 

 hypopygium, femora, tibiae, except the tips, and base of tarsi, yellow, the 

 femora sometimes brown. Head and entire body whitish pollinose, the 

 entire pile white, the bristles, except those of the legs, yellowish-white. 

 Third antennal joint as long as the first and nearly twice as broad, being 

 three fourths as broad as long ; style one-third as long as the third joint. 

 Thorax not distinctly vittate. Wings grayish-hyaline, the costal margin 

 usually a darker gray, veins largely yellow, very narrowly bordered with 

 brown, stigma dark brown, fourth posterior cell closed and short petiolate. 



