248 AMERICAN HYMENOPTERA. 



81. Dorsum of thorax entirely covered with yellow pile ; no black 



interalar band fervidus var. dorsalis. 



Dorsum of thorax not entirely covered with yellow pile 82. 



82. Hypopygium with median carina on apical part pleuralis. 



Hypopygium without median carina 83. 



83. All the first four segments of the abdomen above covered with 



yellow pile fervidus. 



Not all the first four segments of the abdomen above covered with 

 yellow pile 84. 



84. The two apical abdominal segments black 85. 



The two apical abdominal segments bearing long loose pile with a 



more or less distinctly ferruginous-red tinge ; wings light for 

 a queen. Northern 86. 



85. Wings dark ; second dorsal abdominal segment entirely, or for the 



most part, covered above with black pile. Western. 



californicus. 

 Wings rather light ; second dorsal abdominal segment entirely 

 covered above with light or yellow pile. Northwestern. 



kincaidii. 



86. Clypeus smooth and shining, almost impunctate polaris. 



Clypeus somewhat strongly punctate ; third abdominal segment 



entirely and evenly covered above with yellow pile. 



strenuus. 



87. Only the first two abdominal segments above covered with other 



than black pile arcticus. 



Abdomen not so colored 88. 



88. Ocelli large, placed well below the supra-orbital line, in the nar- 



rowest part of the front 89. 



Ocelli small, placed near the supra-orbital line, above the narrowest 

 part of the front 90. 



89. Dorsum of thorax almost entirely covered with light pile. 



nevadensis. 

 Dorsum of thorax not nearly entirely covered with light pile. 



auriconius. 



90. Dorsum of thorax almost or entirely covered with light pile 91, 



Dorsum of thorax not nearly entirely covered with light pile 92. 



91. Only the two apical abdominal segments covered with black pile. 



fervidus var. dorsalis. 

 The three apical abdominal segments covered with black pile. 



sonorus. 



92. Apical segments of abdomen bearing white pile. 



terristris moderatus. 

 Apical segments of abdomen not bearing white pile 93. 



93. Second and third abdominal segments entirely covered with yel- 



low pile above 94. 



Second and third abdominal segments not both entirely covered 

 with yellow pile above 96. 



