MOUNTAIN ANTS OF NORTH AMERICA. 537 



to be his obscuripes. These also undoubtedly bclon<ij to the form I 

 called aggcrans in my "Revision." They are much more hairy than 

 the European rvfa and if the Wyoming types of obscuripes had been 

 like these it is difficult to see how Forel could have overlooked their 

 striking pilosity and have penned the two descriptions above quoted. 

 Pending a more exhaustive study I am willing, however, to attribute 

 both forms to obscuripes and to regard it as a subspecies in which there 

 is considerable variability in pilosity (as in the typical rufa of Europe). 

 But as the term aggerans was suggested to replace Emery's rubiginosa 

 (a preoccupied name), we have still to determine what Emery meant 

 by this form. As he possessed cotypes of obscuripes when he wrote 

 the description of riihiginosa, the latter was evidently something 

 different. After carefully rereading Emery's description I conclude 

 that he must have had a distinct variety of obscuriventris which I 

 believe I am now able to recognize {vide infra under the forms of trun- 

 cicola)} 



108. Formica rufa subsp. obscuripes var. melanotica Emery. 

 Colorado: Boulder (W. W. Robbins). 



Washington: Tacoma (C. C. Adams). 



Alberta: Pincher and Lethbridge (C. G. Hewitt). 



Manitoba: Treesbank (C. G. Hewitt). 



This form, which I have recorded also from Wisconsin, Illinois, 

 South Dakota, Nebraska, Wyoming, Washington and British Colum- 

 bia, is merely a very dark form of obscuripes with only the head red 

 in the largest workers. The true obscuripes does not range eastward 

 of the Rocky Mountains. 



109. Formica truncicola Nyl. subsp. integroides Emery. 

 California: Lake Tahoe (Wheeler). 



Recorded previously from several localities both in the Coast Range 

 and in the Sierras of California. The colonies which I saw in large 

 pine logs and stumps near Tallac and Fallen Leaf Lake were very 

 populous like those of the vars. haemorrhoidalis and coloradensis in the 

 Rocky Mts. The nests were banked with considerable quantities of 

 vegetable detritus. 



3 Since this paragraph was written I have found two worker cotypes of F. 

 obscuripes from Green River, Wyo. in the Pergande Collection (U. S. Nat. Mus.). 

 They have very distinct suberect hairs on the legs, but the pubescence on the 

 gaster seems to be shorter and finer than in workers from Lake Tahoe. ' 



