256 AMERICAN HYMENOPTERA. 



Third antennal segment equalling segment five rufocinctus. 



7. Malar space a mere transverse line fraternus. 



Malar space one-third as long as wide 8. 



8. All the dorsal abdominal segments beyond the second entirely 



covered with black pile 9. 



Not all the segments beyond the second so covered 10. 



9. The second dorsal abdominal segment entirely covered with pile 



of a color other than black 11. 



The second dorsal segment partly covered with black pile. 



separatus. 



10. Third antennal segment as long as segments four and five 



together auricomus. 



Third antennal segment equalling segment five rufocinctus. 



11. Distance between the inner margins of the eyes distinctly greater 



than the width of either eye rufocinctus. 



Distance between the inner margins of the eyes about equal to the 

 width of either eye niornionorum. 



12. Apical segments of abdomen with dull ferruginous yellow pile ; 



western nevadensis. 



Apical segments of abdomen with black pile ; mostly eastern. 



auricomus. 



13. Hairs fringing hind tibiae on the outer surface with a more or less 



distinctly light or ferruginous tinge 14. 



These hairs entirely or almost entirely black 15. 



14. Hind femora with little or no light or yellow pile 16. 



Hind femora with considerable light or yellow pile 18. 



15. Pleura clothed with yellow or light pile from wing bases to bases of 



legs 21. 



Pleura clothed largely with dark pile 22. 



16. Second dorsal abdominal segment entirely covered with yellow 



pile 37. 



Second dorsal segment seldom entirely covered with yellow pile ; 

 western 17. 



17. Apical abdominal segments usually covered with white pile, with- 



out a distinct ferruginous tinge ; third dorsal abdominal 

 segment usually not entirely covered with yellow pile. 



occidentalis. 

 Light pile on apical abdominal segments usually with a distinct 

 ferruginous-red tinge ; third dorsal abdominal segment en- 

 tirely covered with yellow pile ; mostly Californian. 



occidentalis-nig-roscutatus. 



18. Malar space fully one-half as long as the eye 19. 



Malar space not one-half as long as the eye 20. 



19. Pleura usually heavily shaded, darker than anterior part of dorsum 



of thorax kincaldii. 



