292 THE ENTOMOLOGIST. 



NEW AMERICAN BEES.— VII. 

 By T. D. a. Cockerell, 



Oligotropus, Robertson. 

 Robertson (Trans. Am. Ent. Soc. xxix.) has segregated from 

 Megachile, under the name Oligotropus, a species which he 

 names 0. campaiiulce, but which is evidently the same as that 

 formerly reported as Megachile exilis. I possess a specimen of 

 this from Robertson, but I have not seen the true M. exilis, 

 Cresson, described from Texas. The group is a distinct one, 

 and possibly deserves generic rank ; in addition to the characters 

 reported by Robertson, it has some peculiarities of the galea and 

 maxillary palpi, as indicated in Ann. & Mag. Nat. Hist., March, 

 1902, p. 232. Upon comparing the available materials, I am 

 able to discriminate several closely allied species or races, occu- 

 pying different regions. These may be separated as follows : — 



Anterior tarsi of male pale ferruginous (Humid lower 



austral zone of Texas) . . . Megachile exilis, Cresson. 

 Anterior tarsi black or brownish black . . . 1. 



1. The two middle nodules on lower edge of female cly- 



peus much closer together than the distance from 

 either to the lateral nodule ; female about 10 mm. 

 long ; abdominal bands in both sexes very narrow, 

 but distinct, and pure white (Boulder, Colorado, 

 July 24th to Aug. 4th, 1908, S. H. Rohwer) 



Megachile subexiUs, n. sp. or subsp. 



The nodules nearly equally spaced, but the interval be- 

 tween the lateral and median ones large ; insect a 

 little larger and more robust than the last, with the 

 abdominal bands very distinct, and yellowish (West 

 Fork of Gila River, New Mexico, July 16th, C.H. T. 

 Townsend ; Rio Ruidoso, New Mexico, on flowers 

 of Vicia aff. imlchella, alt. 6700 ft., July 27th, male, 

 C. H. T. Townsend) 



Megachile semiexilis, n. sp. or subsp. 



The small lateral nodules very close to the median 



ones ; abdominal bands only moderately distinct . 2. 



2. Last ventral segment of female with black hair ; lower 



margin of clypeus strongly arched or concave 

 (Southern California) . . Megachile angelarum, Ckll. 



Last ventral segment of female with light hair ; lower 

 margin of clypeus scarcely arched (Southern Illinois, 

 Robertson ; Indiana, from Lovell) 



Megachile campamdce (Rob.). 



M. semiexilis is the species of New Mexico hitherto recorded 

 as exilis ; the mouth-characters recorded in Ann. Mag. Nat. 

 Hist, (as cited above) under exilis were derived from semiexilis. 

 I have a series of each of the Rocky Mountain forms, and there 



