Records of Bees. 125 



liair Inifrely black, but some pale on middle and hind femora, 

 and long and mainly pale on anterior femora and tibia3 

 behind. First two abdominal segments with long white hair, 

 some black at extreme sides of first segment, and short black 

 hair along extreme base of second ; third with mixed black 

 and pale; the other segments nearly all black; in certain 

 lights there is a strong suggestion of pale hair-bands; sixth 

 segment quite entire ; seventh with a pair of coin|)aratively 

 short teeth, wide apart ; first ventral segment entire, third 

 deeply emarginate, the emargination ciliate with reddish. 

 The second and third joints of middle tarsi have a strongly 

 swollen or inflated ap-pearance. Third antennal joint shorter 

 than fourth. Spurs normal. 



This must be closely allied to 0. integra. Cress., which I 

 know only from the description ; but it is smaller, the hair 

 not (or barely) ochreous-tinted above, the legs apparently 

 with more pale hair ; the abdomen with more pale hair; and 

 the fringe on middle of third ventral segment can hardly be 

 said to be long and golden. Cresson also makes no allusion 

 to any peculiarity of the middle tarsi of integra, though in 

 the species described just before he describes and figures 

 tarsal structures. It does not fit into any of the Ilobertsonian 

 subgenera. 



In my table of Boulder County species 0. integrella runs 

 nearest to 0. viridior, or, perhaps, to cyaneonitens. The 

 three are readily separated thus : — 



Larger ; hair ou anterior tibite behind dense, rather short, 

 and wlioUy black, contrasting with the long white 

 hair on their femora beliind viridior. 



Smaller ; hair on anterior tibise behind long and mainlv 



white '. integrella. 



Size about as in integrella, but very different by the dark 

 purple-blue abdomen, without conspicuous light hair, 

 much larger head and broader face, notched sixth 

 segment, &c cyaneotiitens. 



The face of integrella is rather unusually narrow, the eyes 

 converging below, and is densely covered with white hair. 



0. universitatis, Ckll., has the same type of coloration and 

 the same sort of middle tarsi as integrella; but it is smaller 

 than the latter and has not the conspicuous black hair on the 

 sides of the thorax posteriorly or on the cheeks. In universi- 

 tatis the middle fen)oni and tibiaj have the hair beliind 

 brilliant white, with some black intermixed ; in integrella 

 this hair is black, with a few glittering white hairs. The two 

 are obviously of the same immediate group, but apparently 

 not varieties of a single species. 



