ZENILLIA AND ALLIED GENERA SELLERS 73 



l>isk of Scutellaria covered with long, fine, erect hairs; there is a tendency to 

 lack a discernible pair of discal scutellars (Nearctic species) 



3. theclarum (Scudder) (p. 76) 



4. 1'ostsutural dorsocentral macrochaetae four 7 



Postsutural dorsocentral macrochaetae three 5 



5. Palpus yellow; costal spine short 6 



Palpus brownish yellow ; costal spine long ; front at vertex about one-third 



width of head, of about equal breadth in both sexes; third segment of 

 antenna hardly twice length of second; arista thickened on more than 

 basal one-half, penultimate segment elongate; pulvilli of male only slightly 



longer than pulvilli of female 4. trisetosa (Coquillett) (p. 78) 



Palpus black, costal spine short; arista thickened on basal one-fourth to one- 

 third, penultimate segment short 



8. crassiseta (Aldrich and Webber) (p. 84) 

 6. Middle tibia with three or more median anterolateral bristles; three sterno- 

 pleural macrochaetae; scutellum rufous, black at base; apical scutellars 

 strong, more or less erect; discal macrochaetae on second and third ab- 

 dominal segments somewhat numerous and irregularly arranged; third 

 segment of antenna about twice length of second 



(Nearctic species) 5. estigmenensis, new species (p. 79) 



[Palearctic species) 6. affinis Fallen (p. 81) 



Middle tibia with one median anterolateral bristle; third vein bristly to small 



cross vein; two sternopleural macrochaetae and a sternopleural bristle; 



scutellum black ; apical scutellars weak ; no discal macrochaetae on second 



or third abdominal segments; third segment of antenna more than three 



times the second 7. setinervis (Coquillett) (p. 83) 



7. Palpus yellow 1- 



Palpus black or predominantly so 8 



S. Scutellum black: apical scutellars turned backward 9 



Scutellum yellow on apical half and black on basal half ; apical scutellars erect 

 or proclinate; subapical scutellar bristles very long, reaching to third 



abdominal segment 8. crassiseta (Aldrich and Webber) (p. 84) 



9. Several small hairs on upper part of parafacial situated directly below lowest 

 frontal bristles; two pairs of discal macrochaetae or bristles on second and 

 third abdominal segments, anterior pair often weaker; one reclinate pre- 



vertical bristle, female sometimes with two 11 



Small hairs directly below lowest frontals lacking; one pair of discal mac- 

 rochaetae on second and third abdominal segments ; two reclinate prevesi- 

 cal bristles 10 



10. Midtibia with one median anterolateral bristle; third segment of antenna in 



male four and one-half and in female four times length of second segment ; 

 arista thickened on basal one-third, penultimate segment about as long as 



broad 9. neurotomae, new species (p. 85) 



Midtibia with two or three median anterolateral bristles: third segment of 

 antenna in male three and one-half and in female twice length of second ; 

 arista thickened on basal one-third to two-fifths, penultimate segment 

 long 10. confusionis, new species (p. 86) 



11. Parafrontal, face, and gena silver-gray pollinose (some specimens with a dis- 



tinct tawny or brassy tinge to parafrontal) in female, with parafrontal be- 

 coming blacker toward the vertex; front at narrowest in male about 0.25 

 and in female 0.29 head width ; third segment of antenna in male four and in 

 female three times length of second segment ; arista thickened on basal two- 

 fifths in male, on basal one-third in female, penultimate segment elongate 



