596 PROCEEDINGS OF THE ACADEMY OF [Auii., 



Second submarginal cell receiving recurrent nerviire before or at 



its middle, G. 



G. Larger; yellow marks on second abdominal segment almost meet- 

 ing in middle line, hella, Cress. 



Smaller; yellow marks on second abdominal segment widely sepa- 

 rated cuneata (Rob.). 



7. Abdomen long and narrow, bright red, with very widely separated 

 yellow spots on second and third segments ; second submarginal 

 cell receiving recurrent nervure a little beyond its middle; 

 scape red tinged with yellow in front; second submarginal cell 

 broad (Nevada), physvra, Ckll. 



Not so, 8. 



S. Rocky Mountain species; mesothorax with more or less red; lat- 

 eral margins of metathoracic enclosure curved inward; third 

 antennal joint on upper side at least as long as fourth; no black 

 spots on red part of first abdominal segment, 9. 



Species of the country east of the Rocky Mountains, going west in 

 the north to Washington State; mesothorax rarely with any red, 

 when with red, lateral margins of metathoracic enclosure pi'ac- 



tically straight, 10. 



9. Third antennal joint short; second submarginal cell narrowed 

 above, and receiving the recurrent nervure at or before its mid- 

 dle (New Mexico), ; schrmrzi contractula, Ckll. 



Third antennal joint longer; second submarginal cell broader 

 above, and receiving the recurrent nervure beyond its middle 

 (Colorado), schrmrzi, Ckll. 



10. Mesothoraxlargely red (Lehigh Gap, Pa.), . perp/ea'a. Cress., var. 

 Mesothorax black, 11. 



11. Size largest; length nearly 10 mm.; e3^es usually jiale; abdomen 



usually with well-developed yellow bands. . . hella, Cress. 

 Size medium; length little over 7 mm., sometimes smaller, . 12. 

 Size smallest; length about 6 mm. or less, . . cimcata (Rob.). 



12. Scape light red in front; spots on light part of first abdominal seg- 



ment practically obsolete; scutellum largely red (New York), 



cuneata var. ? 

 Scape black or dark red in front, 13. 



13. Scape black in front; eyes gray; scutellum black; abdomen with 



cream-colored bands, alhofasciata, Smith. 



Eyes black or nearly so ; scutellum black or red ; two black spots 

 on first abdominal segment distinct (Wisconsin), cuneata var.? 



Nomada lepida, Cresson. 



cJ^ . — Length 7^-8^ mm. ; head and thorax black, with abundant hair, 

 white except on vertex and dorsum of thorax, where it is tinted with 

 brownish-gray, so as to appear dirty; facial quadrangle longer than 

 broad; labrum, basal part of mandil)les, clypeus (but no supraclypeal 

 mark), and narrow lateral face-marks extending to level of antenna^, 

 1 onion-yellow; posterior orbits with a narrow yellow line extending 



