PHILADEMMIIA VIREO, 349 



plumage is often t'ouiid to he stJiiiicd. It is tVccjUcnt ly imposed u|)un 

 by the Cowbird, whose youiit; ones it I'ejirs as tenderly as if they 

 were its own. 



In the east it is said to tia\el as fai- north as Antieosti. liioh- 

 ardsoii found it at Fort Simpson, and accord iiiy- to .Mr. Fannin, it is a 

 summer resident along the southern border of Jh-itish Columbia. A 

 great many spend the winter in the (iulf States, and go even farther 

 south. 



VTKEO PHlLADELPHICrS (Cass.). 

 i*-"J7. Philadelphia Vireo. (Cy2(\) 



Above, (lull olive-greon, biighteiiiiig dii the nuiip, tailing insensibly into 

 ashy on the ci-own, which is not bordered with blackish : a dull white supei'- 

 ciliary line ; below, palest possible yellowish, whitening on thioat and belly, 

 slightly olive-shaded on sides ; sometimes a slight creamy or buffy shade 

 throughout the xuider parts ; no obvious wing bars ; no spurious quill. Length, 

 4i-5^ ; wing, al)out 2§ ; tail, about 2^ ; bill, hardly or about {; ; tarsus f^. 



Hab. — Eastern North America, north to Hudson's Bay, south, in winter, 

 to Costa Rica. 



The only record of the nest and eggs of this species 1 ha\e ever 

 seen is published by Mr. Ernest E. Thompson in the Avk, iov Jul}^ 

 1885. He says: "On the 9th of June, 1884, while camped near 

 Duck Mountain, T found a nest of this species. Tt hung from a 

 forked twig, about eight feet from the ground, in a willow which 

 was the reverse of dense, as it grew in the shade of a poplar grove. 

 The nest was pensile, as is usual with the genus; formed of fine grass 

 and birch bark. The eggs were four in number, and pi'esented no 

 (.)bvious difference from those of the Red-eyed Vireo, but unfortun- 

 ateh' they were destroj^ed by an accident Ijefore thev were measured." 



The owners were not secured. 



Yer}' many of the moi'e recent additions to the list of oui- Ameri- 

 can birds have been made by the discovery that within certain 

 well-known gi'oups Avere individuals differing in some respects from 

 the others. If these differences were found to be uncertain and 

 irregular they received only a passing notice, but if thev were found to 

 be constant they were made the basis on which to build a new species. 



Thus, although the American Vireos had passed in reAiew before 

 many distinguished ornithologists, it was not until ]84'2 that John 

 Cassin found one closely I'esembling sevei-al of the others, but differ- 

 ing in some respects from all of them. 



In 1851, he published a description of the liird he liad found, 



