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U. S. p. R. R. EXP. AND SURVEYS — ZOOLOGY — GENERAL REPORT. 



the second quill. The third quill is longest ; the fourth and fifth successively a little shorter ; 

 the second a little longer than the sixth, about .25 of an inch shorter than the third, much 

 longer than the secondaries. The tail is slightly emarginate and rounded. 



The contrast between the ashy of the head and the ashy olive is very little marked, the colors 

 not separated by any well defined line. The white stripe on the side of the head is not well 

 defined ; anteriorly it has a yellowish tinge ; the dusky of the lore is not very decided. The 

 dusky of the lore is continued through, and a little behind the eye. The sides of the neck 

 along the throat have rather more yellowish in their brown. There is a brownish tinge in the 

 yellowish on the side of the body. The under tail coverts are faintly tinged with yellowish. 



Specimens vary a little in the amount of yellow beneath, which, however, very seldom be- 

 comes conspicuous ; it is usually brightest on the abdomen. 



This species is readily distinguished from all the other American Vireos with spurious first 

 primary, by the plain colors and absence of pale margins to the outer webs of the quills. 

 Some Vireosylvas have no more white in the wings, but these lack the spurious primary. 



While all the specimens of Vireo gilvus from the Eastern States have the proportions of the 

 quills nearly as described, all from the Pacific coast (five) agree in having the wings more 

 rounded, the third and fourth about equal, the fifth a little shorter, the second about equal to, 

 or only a little longer than the seventh, .15 of an inch shorter than the sixth, and .30 

 shorter than the third. The bill is smaller, more depressed, and darker above. It is probably 

 to a specimen of this bird that Swainson alludes in his article on Vireo hartramii, as having 

 been taken on the Columbia river by Douglass, but immature and injured by insects. The 

 proportions of the quill are the same, if the spurious quill be taken into the account, which 

 would advance his numbers by one throughout, (second and seventh about equal instead of first . 

 and sixth, &c.) The description, however, is really based on the Brazilian specimen referred 

 to, which is entirely distinct. 



Should the western specimens really prove distinct, they may appropriately bear the name of 

 Vireo swainsonii. 



List of specimens. 



