OEEATOMYIELLA AND PARADIDYMA — EEINHAKD 21 



Abdomen wholly gray poUinose ; palpi dark brown ; sterno- 

 pleurals, 3 ; infrasquamal hairs present ; larger species, 

 length 8 mm (8) neomexicana, new species. 



4. Sides of face bare below level of arista outside main row of 



bristles 5. 



Sides of face outside main row of bristles with coarse black 

 hairs extending almost to cheeks ; pollen on head golden ; 

 abdomen wholly pollinose (Mexico). 



(14) aperta Brauer and Bergenstamm. 



5. Fourth abdominal segment with a row of discals extending 



across the top 9. 



Fourth abdominal segment without median discal bristles above 6. 



6. Outer verticals not developed 7. 



Outer vertical bristles almost as large as inner ones ; abdomen 



wholly gray pollinose; arista thickened beyond middle 



(Peru) (24) armata (Townsend). 



7. Venter of abdomen clothed with only short black hairs 8. 



Venter bearing long pale or whitish hairs; palpi black; 



wings strongly infuscated ; antennae wholly black (Peru). 



(17) piliventris, new species. 



8. Arista thickened on proximal two-thirds, bare ; third antennal 



segment yellow on basal half, five to six times longer than 

 second ; parafacial at narrowest part but slightly wider 

 than third antennal segment ; pollen on intermediate abdomi- 

 nal segments extending thinly to hind margin (Peru). 



(16) peruana (Townsend). 

 Arista thickened at base, very slender on apical two-thirds, 

 clothed with short hairs to tip; third antennal segment 

 black, narrowed toward base, about two and one-half times 

 length of second ; intei-mediate abdominal segments with 

 defined silvery bands on basal third (Central America, 

 Vera Oruz) (15) aldrichi. new species. 



9. Apical cell of wing closed and petiolate; outer vertical bristles 



absent 11. 



Apical cell open ; outer verticals nearly half as long as inner 

 pair 10. 



10. Epaulets reddish yellow; arista thickened on proximal fourth, 



distinctly short haired to tip ; mesonotum covered with thick 

 lusterless yellowish gray pollen, the dark stripes very in- 

 conspicuous and visible only in a flat rear view; abdomen 

 largely pollinose, third and fourth segments at most sub- 

 shining on narrow hind margins (18) apicalis, new species. 



Epaulets black ; arista thickened almost to middle, pubescent ; 

 mesonotum gray pollinose, the black stripes distinct, not in- 

 terrupted at suture; last three abdominal segments shining 

 black on apical half or more (19) affinis, new species. 



11. Mesonotum subshining, lightly dusted with pollen, the dark 



stripes hardly apparent ; arista thickened on basal fifth to 

 fourth ; abdomen black and shiny, basal fourth of segments 



2 and 3 thinly gray pollinose at most (23) petiolata, new species. 



Mesonotum densely gray pollinose and vittate, the black siripes 

 usually fused into a single broad pair, which extends to 

 base of scutelluni ; arista tlilokened about to middle; last 

 three abdominal segments conspicuously pollinose on basal 

 third to half (22) singularis (Townsend). 



