254 AMERICAN HYMENOPTERA. 



58. Greater part of dorsum of thorax with yellow and black hairs inter- 



mixed giving it a strongly clouded appearance 65. 



Black interalar band more or less distinct 67. 



59. Pile on third dorsal abdominal segment entirely or almost entirely 



black arcticus. 



Pile on third segment more or less strongly yellow kincaidii. 



60. Ocelli large ; well below the supra-orbital line, in the narrowest 



part of the front crotchii. 



Ocelli small ; near the supra-orbital line 61. 



61. Occiput with more or less yellow pile; third abdominal segment 



entirely covered above with black pile ; malar space not one- 

 third as long as the eye frigidus. 



Occiput black ; third abdominal segment not entirely covered above 

 with black pile ; malar space one-third as long as the eye. 



polaris. 



62. Pile long and loose ; some of the dorsal abdominal segments ferru- 



ginous-red 79. 



Pile not long and loose ; none of the dorsal abdominal segments 

 ferruginous 63 . 



63. All the first four abdominal segments covered above with yellow 



pile fervidus. 



Not all the first four abdominal segments entirely so covered.... 64. 



64. Malar space much longer than it is wide at its apex. 



californicus. 

 Malar space not much longer than it is wide at its apex. 



occidentalis var. nigroscutatus. 



65. Apical abdominal segment dark cockerelli. 



Apical abdominal segment ferruginous-red or yellowish-ferrugin- 

 ous 66. 



66. Length of malar space greater than its width at the apex. 



sitkensis. 

 Malar space as wide at its apex as it is long niixtus. 



67. Occiput bearing little or no yellow pile 68. 



Occiput yellow or with a strong admixture of yellow hairs 70. 



68. Malar space as long as or longer than its width at the apex 69. 



Malar space wider at apex than it is long 78. 



69. Third dorsal abdominal segment entirely covered with black pile..72. 

 Third dorsal abdominal segment not entirely covered with black 



pile 73 . 



70. Apical abdominal segments bearing ferruginous-red pile. 



frigidus. 

 Apical segments not bearing ferruginous pile 71. 



71. Second abdominal segment entirely yellow and third entirely black 



above couperi. 



Not so colored 76. 



