100 AMERICAN HYMENOPTERA. 



Male. Head. — Face with only cinereous (black and whitish hairs 

 mixed) pile. Occiput entirely dark. Ventro-lateral portions with 

 mostly cinereous or pale pile. Malar space distinctly longer than its 

 width at apex, nearly one-fourth as long as eye. Clypeus mostly naked 

 and moderately punctate, the punctures over the greater part of the 

 disc being for the most part rather delicate. Fifth antennal segment 

 much longer than third and third much longer than fourth. 



Thorax. — Coloration of pile much like that of queen and worker, 

 but with the yellow pile on the front part of the dorsum reaching back 

 to nearly even with the tegulae all the way across ; metapleura and 

 sides of median segment clothed rather densely with pure pale yellow 

 pile. 



Abdomen. — Dorsum : segments one, two and three entirely covered 

 with pale yellow pile ; segment four mostly dark, but with apical mar- 

 gin bearing whitish yellow pile and with yellow hairs more or less ad- 

 mixed with the black, except on the very middle portion, the extreme 

 sides having this yellowish admixture very strongly; segment five 

 mostly dark, but with a fringe of whitish hairs on the middle of the 

 apical margin ; segment six dark, but with apical margin bearing fer- 

 ruginous hairs ; segment seven with ferruginous clothing. Venter with 

 mostly whitish-yellow pile. 



Wings. — Very light, almost clear transparent, only slightly infuscate. 



Legs. — Coxae all with some pale hair, at least on their outer sides ; 

 trochanters all with considerable pale pile on their lower sides ; femora 

 mostly dark, but at least the middle and hind pair with considerable 

 pale yellow on the lower sides of their basal halves ; tibias all dark. 

 Outer faces of hind tibiae convex and hairy, the hind fringes long and 

 the front ones moderately so, forming very weak corbiculse. Hind 

 metatarsi with outer faces nearly flat and hind fringes, for most part, 

 short. 



Dimensions. — Length: queen, about 19 mm.; worker, about 12^ 

 mm. ; male, nearly 14 mm. 



Variation. — The description of the color variant {laticollis) 

 is as follows : Like typical nigrodorsalis queen, but with band 

 of yellow pile, running across anterior part of dorsum of 

 thorax, much wider and reaching back in the middle to even 

 with the tegulse. Middle and hind trochanters and bases of 

 hind femora beneath bearing considerable yellow pile. Hind 

 fringes of corbiculse strongly ferruginous. 



This species has its closest relative in montezumce. 



Bonibiis (Boinbiis) wiliuatt?e Ckll. 

 Bombus ephippiaius, var. d., Ant. Handlirsch, Ann. Naturh. Hofmus. 

 Wien., Ill, 1888, p. 233, S . 



