358 AMERICAN HYMENOPTERA. 



Queen. Head. — Elongate. Face black, but with a very faint sprink- 

 ling of light hairs (visible with a lens) about the bases of the antennae ; 

 occiput black, but often with a very faint sprinkling of yellow hairs 

 (visible with a lens) in the middle; cheeks dark. Labrum with tuber- 

 cle-like areas well separated, their margins rounded and summits flat 

 or slightly concaved ; the surface between them, and above the shelf - 

 like projection, excavated ; the shelf-like projection narrow and not 

 prominent. Malar space longer than its width at the apex, about one- 

 fourth as long as the eye. Clypeus very sparsely and delicately punc- 

 tate over the disc, smooth and shining, the corners coarsely punctate. 

 Flagellum of antenna about twice as long as the scape ; the third an- 

 tennal segment much longer than the fifth, the fifth very slightly 

 longer than the fourth. 



Thorax. — Front part of dorsum bearing a mixture (of varying pro- 

 portions) of black and yellow pile ; the region between the bases of the 

 wings black, usually with an admixture of yellow hairs toward the sides ; 

 scutellum covered with yellow pile, but with an admixture of black 

 hairs in front, especially in the middle ; center of disc bare, smooth 

 and shining ; mesopleura covered with yellow pile to the bases of the 

 legs ; metapleura and sides of the median segment clothed with yellow 

 pile. 



Abdomen. — Dorsum: segments one and two yellow; segments three 

 and four black ; segment five yellow ; segment six black. Venter 

 mostly black. 



Wings .—Only moderately stained with brown. 



Legs. — The hind coxse usually with some yellow hair on their outer 

 sides ; the trochanters and usually the very bases of the femora with 

 more or less yellow pile on their lower sides ; the femora and tibiae 

 mostly black. 



Worker. — Much like the queen, but with somewhat lighter wings ; 

 the coxae, trochanters and femora often entirely black ; the anterior 

 part of the dorsum of the thorax usually without an admixture of 

 black hairs with the yellow ; face often entirely black. Malar space 

 somewhat variable, sometimes not longer than its width at the apex. 

 Venter often with considerable yellow pile on the sides of the apical 

 margins of the third, fourth and fifth segments. 



Dimensions .—'Length : queen, 14 mm. to 16 mm. ; worker, 10 mm. 

 to 13 mm. Spread of fore wings : queen, 32 mm. to 34 mm. ; worker, 

 23 mm. to 28 mm. Width of abdomen at second segment : queen, 8^ 

 mm. to 9 mm. ; worker, S\ mm. to 7 mm. 



This species appears to be most closely related to B. 

 vagans, from which it may be readily separated by the differ- 

 ent coloration of the pile on the dorsum of its thorax and 

 on its fifth dorsal abdominal segment. 



