37'g NORTH AMERICAN BIRDS. 



gest, third (measured from exposed base of first primary), 2.54 ; length of bill from fore- 

 head, .55, from nostril, .31. along gape, .70; tarsus, .75; middle toe and claw, .GO, claw 

 alone, .21; hind toe and claw, .50, claw alone, .23. 



Hab. Southern Rocky Mountains; East Humboldt Mountains, Nevada (Ridgwat). 

 In winter to Coliraa, Mexico. 



Wliile the pattern of coloration is precisely similar tu that of Lanivireo 

 solitarius, the dift'erence in the colors appears to be occasioned merely by re- 

 moving, as it were, the yellow stain, which on the plumbeous produces the 

 olive-green tinge, and exists in a purer tint along the sides, leaving, essentially, 

 only clear plumbeous and pure white ; there is, however, in the most typical 

 specimens, always a faint tinge of green on the rump, and a stain of yellow 

 along the side. Though identical with solitarius in most of its proportions, 

 the wings and tail are considerably longer than in the average of that form. 



There are many specimens from the Rocky Mountains and westward that 

 are so decidedly intei-mediate between soliiarms and I'lamhcics, that, consider- 

 ing also the lack of essential difference in foim and coloration between the 

 two, we do not hesitate to consider them, along with cassini and 2)ropinquus 

 (see page 373), as races of a single species, of wliich each is the representa- 

 tive in a particvdar region. Thus, V. solitarius breeds in the Eastern Prov- 

 ince of the United States (and possibly in the Western, following the same 

 route far to the northward that many Eastern birds pursue in straggling 

 westward), and migrates in winter into Middle America as far as Guatemala ; 

 those which breed in the Northwest pass directly southward, tlius crossing the 

 region where cassini and plumbeus breed, which accounts for their being ob- 

 tained together. V. cassini is the representative on tlie opposite side of the 

 continent ; but the history of its migrations is yet obscure. V. plumbeus is 

 the j\Iiddle Province and Ptocky Mountain representative, breeding alone in 

 that region, and in winter migrating southward tlirough Western Me.x;ico as 

 far as Colima. V. propinquus is another permanent race, V)ut a local one, be- 

 ing resident in the country where found, though mixed in winter with visitors 

 of solitarnis from the North. 



Habits. Of this very recently discovered race, very little is at present 

 known. It was first described by Dr. Coues, who met with it in Arizona, 

 near Fort Whipple. He says it is especially abundant in the northern part 

 of that Territory. It was by far the most common Vireo at Fort Whijiple, 

 where it is a summer resident, arriving there about the 15th of Ajiril and 

 remaining until October. 



It was found to be common about Laramie Peak, by Dr. R. Hitz, and was 

 also met with in winter on the plains at Colima, Mexico, by Xantus. 



It was seen in the .summers of 1868 and 1869, by Mr. Ridgway, among 

 the cedar and nut-pine woods on the slopes and among the brushwood in the 

 canons of the East Humboldt Mountains, being most partial to the former 

 situations. There, too, it undoubtedly breeds, as in the latter part of July 

 yoimg birds, unable to fly, were met with by him. He alsc; states that the 



