434 AMERICAN HYMENOPTERA. 



Color Variant. — Worker like the typical form, but with the third 

 dorsal abdominal segment entirely, and very often also the basal mid- 

 dle of the fourth, covered with yellow pile. Many specimens from 

 Arizona, New Mexico, Colorado and Utah. 



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

 Utah, Nevada, California (Chino, Los Angeles, Mt. Shasta), 

 Arizona (Flagstaff and Southern Arizona) and New Mexico, 

 and it probably ranges throughout the greater portion of the 

 Transition Zone in those states. That it runs over into the 

 Upper Austral Zone a little, is shown by the following records 

 from western Nebraska : Warbonnet Canon, Sioux County, 

 and Gering (very rare) (Swenk in Ent. News, July, 1907). 

 What are its northern and southern limits ? Does it range 

 into Mexico ? My most northern record is Mt. Shasta, Cali- 

 fornia, and my most southern is " southern Arizona." It 

 seems to be a fairly common species throughout a consider- 

 able portion of its habitat. 



This species is apparently most closely related to B. crot- 

 chiiy with which, however, it does not seem to be very 

 closely allied. 



The queens of this species are very striking in appearance. 



Boiubus (Bonibias) crotcliii Cress. 

 Bombus crotchii Cresson, Proc. Acad. Nat. Sci. Phila., 1878, p. 184, 9 . 

 •• " Cresson, Trans. Amer. Ent. Soc, VII, 1879, p. 23 



(Catal.). 

 " " Cresson,Syn.Hym.No. Amer., 1887, p. 307 (Catal.). 



" nigrocindus Provancher, Addit. Faun. Canada. Hymen., 1888, 

 p. 342, 9 . 

 crotchii Dalla Torre, Cat. Hym., X, 1896, p. 515. 



Fowler, Rep't Cal. Agr'l Exp. Sta., 1902, Part II, p. 

 317. 

 improbus Howard, Insect Book, 1904, Plate II, fig. 13, cf . 



Types. — Queen in the collection of the American Entomo- 

 logical Society. The male figured in Dr. L. O. Howard's 

 "Insect Book" as B. improbus was used, with others, in 

 making the description given below, and this specimen must 

 be considered as the type of this sex. The male and the 

 worker cotypes (here described for the first time) are all in 

 the collection of the United States National Museum. 



