HENRY J. FRANKLIN. 289 



one of the common species. It is probably yet to be reported 

 from Arizona, Lower California (northern part), Alberta, 

 western Assiniboia, western Saskatchewan and western Atha- 

 basca. It probably is not present in any of the states east of 

 those above mentioned or in Mexico proper. It appears to 

 be confined mainly to the Canadian and Transition Zones, 

 and it seems not improbable that it may range throughout a 

 considerable portion of Alaska. 



This species has by far its closest ally in the European B. 

 distinguendus Morawitz, of which it is probably merely a 

 variety, though I have not been thus far able to prove that 

 such is the case. B. distinguendus has the pile on the ante- 

 rior part of the dorsum of the thorax strongly yellowish in- 

 stead of whitish as in this species. This species is compa- 

 ratively very constant in all its important characters. 



THE KIRBYELLUS GROUP. 

 Type. — Bombus kirbyellus Curtis. This group is newly 

 established in this paper. 



Characters of the Group. 



Females. — Pile long and fine. Head very long triangular in 

 outline ; mandibles as in Pratorum group ; malar space reach- 

 ing its maximum in length ; clypeus rather sparsely punctate, 

 except at corners ; hypopygium without median carina. 



Males. — Head shaped much like that of female ; antennae 

 moderately long and slender ; posterior tibiae with outer face 

 very slightly convex and fringed in front and behind with 

 very long hairs, forming a very distinct pollen basket ; hind 

 margins of posterior metatarsi fringed with long hairs. 



Genitalia. — Claspers (figs. 63 and 77) long and rather 

 slender in appearance ; branches with broadly rounded apices, 

 viewed from above ; volsellas very long and slender, gradu- 

 ally tapering from the base and with a broadly rounded and 

 irregularly serrate-margined apical projection ; squamae ob- 

 long or irregularly triangular in outline, with the inner lobe 

 vestigial or absent. Sagitta with very irregularly shaped 

 head, this being bidentate at base on outer side and with 

 apex foliaceous and recurved downward. 



TRANS. AM. ENT. SOC. , XXXVIII. (37) 



