340 AMERICAN HYMENOPTERA. 



sides of head often with more or less yellow pile, sometimes entirely 

 dark. Malar space somewhat longer than its width at apex ; about 

 one-fourth as long as the eye. Flagellum of antennae about three 

 times as long as scape ; third antennal segment and fifth sebequal, the 

 fourth shorter than either. 



Thorax. — Coloration much as in females for most part, but the black 

 interalar band, as a rule, narrower and less sharply defined — nearly 

 obliterated in many specimens ; pleura always entirely yellow to bases 

 of legs. 



Abdomen. — Dorsum : segments one, two and three colored as in fe- 

 males ; segment four entirely yellow ; segment five sometimes entirely 

 yellow, but usually with more or less black in the middle ; segment six 

 sometimes entirely black, but usually with more or less yellow pile on 

 the sides; segment seven mostly black, but often with a few yellow or 

 ferruginous hairs about the tip. Venter clothed with mostly yellow 

 pile. 



Genitalia. — Much like those of B. ternarius Say (fig. 65), but with 

 the inner margins of the squamae straight or slightly outcurved, not in- 

 curved. 



Wings. — Very light, subhyaline. 



Legs. — Coxae, trochanters and femora bearing a considerable amount 

 of light yellow pile ; fore and middle tibiae usually with more or less 

 yellowish or ferruginous pile on their posterior sides ; hind tibiae with 

 fringes long and more or less strongly light or yellow ferruginous ; 

 outer faces of hind tibiae somewhat convex and bare, except for a sparse 

 scattering of hair over them ; hind metatarsi with rather long fringes 

 of light ferruginous hair on the basal two-thirds of their posterior 

 borders. 



Dimensions . — Length : queen, 13 mm. to 17 mm. ; worker, 9 mm. 

 to 12 mm. ; male, 10 mm. to 13 mm. Spread of wings: queen, 29 

 mm. to 32 mm. ; male, 24 mm. to 27 mm. Width of abdomen at 

 second segment : queen, 7 mm. to 8 mm. ; male, about 6 mm. 



Redescribed from a large number of specimens of each 

 caste. 



Habitat. — I have records of this species from Alaska, 

 Yukon, Mackenzie (Great Slave Lake) and the old territory 

 of Saskatchewan on the west and from Labrador (Nain and 

 Rama), Ungava (Rigolet and Ungava Bay) and Hudson Bay 

 Country (Fullerton) on the east, and it probably ranges 

 through all the intervening country. What are its southern 

 limits ? It does not appear to be present in the United 

 States and is a strictly Boreal form. The most northern 

 record which I have is Point Barrow, Alaska, North Latitude 



