Theodore h. frison 310 



variety of pleuralis from Alaska. The specimens described 

 as alaskensis and dimidiatus by Ashmead in his report on the 

 Hymenoptera taken by the Harriman Alaskan Expedition in 

 1902 are, as stated by Franklin, the species called flavlfrons. 

 I wish, however, to recognize Ashmead's name dimidiatus 

 as a varietal name for the specimens of this species lacking 

 ferruginous pubescence on the third and fourtii dorsal alxlominal 

 segments. 



The fact that the male selected as the lectotype of flavifrons 

 belongs to another species is unfortunate, but does not offer 

 sufficient grounds for considering y/ay?/ro/;.s as synonymous with 

 pleuralis. Cresson's original description of the queen oi flavifrons 

 in 1863, certainly applies to the species we have been calling 

 flavifrons. His description of the male, which follows the de- 

 scriptions of the queen and worker, indicate, however, that it 

 was based upon specimens of pleuralis. As there is no means 

 of proving that the lectotype and paratype males ])earing the 

 label "R. A." are from the type locality, "Ft. Youcon, Arctic 

 America," it is advisable to retain the name flavifrons. 



The determinations of males Ijelonging to the above species 

 has been a constant source of perplexity to persons engaged in 

 the determination of bumblebees. In this connection it seems 

 well to note that the presence of a sharply defined black band on 

 the dorsum of the tliorax ])etween the wings in a male of this 

 complex denotes pleuralis; a mixture of black and yellow pu- 

 bescence on the anterior dorsal portion of the thorax, flavifrons; 

 dorsum of thorax mostly pure yellow, except for a very poorly 

 defined black band between wings, centralis; and sitkensis as 

 descril)ed by Franklin. The length of the malar space in all 

 castes is longer in flavifrons than in centralis. 



A study of two cotype workers of B. and)iguus (Franklin) 

 convinces me that amhiguus is merely a slight color variety of 

 flavifrons. The malar space in both cotyi)es is considerably 

 longer than the length of the malar space in specimens of sitkensis 

 (Nylander), thus agreeing in this res[)ect with flavifrons. 

 Franklin considered amhiguus as most closely allied to sitkensis. 

 It is to be noted also that the pubescence of ambiguus is short, 

 another attribute oi flavifrons. In sitkensis the pubescence is 



THANS. AM. ENT, SOC, XLVUI. 



