VIREO. 471 



<P. Exposed culmen not more than .40. 



Above grayish olive-green, becoming more decidedly gray- 

 ish on top of head ; a whitish superciliary stripe ; lower 

 parts very pale sulphur-yellow, deepest on chest, the chin 

 and belly white; length about 4.80, wing 2.50-2.75, tail 

 1.90-2.20, exposed culmen .38-.40. Hob. Eastern North 

 America, north to Manitoba and Hudson's Bay (breeding 

 chiefly north of United States) ; south, in winter, to Guate- 

 mala, Costa. Eica, and Chiriqui (but not yet recorded 

 either from Mexico or from any part of West Indies). 



626. V. philadelphicus (CAss.). Philadelphia Vireo. 

 <. Wing with a well-developed spurious primary, longer than bill ; exposed 



culmen much less than .50. 



d 1 . Top of head dull ash-gray, not distinctly different from the grayish 

 olive, or olive-gray, of back. (Adult: Above olive-grayish, 

 becoming more decidedly gray on top of head, more tinged 

 with pale olive-greenish on rump and upper tail-coverts ; a 

 whitish loral streak, extending back over eye, but scarcely 

 beyond it; malar region, ear-coverts, and sides of neck pale 

 brownish gray or pale grayish buffy ; lower parts dull white, 

 more or less tinged with olive-yellowish laterally. Young : Top 

 of head and hind-neck very pale grayish buff, the lores and 

 superciliary region white ; ear-coverts still paler buffy ; back, 

 scapulars, rump, and lesser wing-coverts buffy grayish ; lower 

 parts entirely pure white, except under tail-coverts, which are 

 pale yellow ; wings and tail as in adult, but greater wing- 

 coverts tipped with dull grayish buffy.) 



e 1 . Larger, with stouter bill ; upper parts (especially top of head) 

 averaging rather paler and clearer grayish, the flanks more 

 yellowish (or less olivaceous), the colors generally clearer 

 or " cleaner" ; length 5.00-5.50, wing 2.65-2.95 (2.84), tail 

 2.10-2.40 (2.22), bill from nostril .30-.32 (.31), depth at 

 base .15-.18 (.16), tarsus .68-.72 (.70). Nest in trees, usu- 

 ally at a considerable height, in open copses, along banks 

 of streams, or in shade-trees along streets in towns and 

 cities. Eggs .75 X -55. Hob. Eastern North America, 

 north to Fort Simpson and Hudson's Bay, west to Great 

 Plains ; south, in winter, to eastern Mexico. 



627. V. gilvus (ViEiLL.). Warbling Vireo. 



e 2 . Smaller, with slenderer bill ; upper parts (especially top of 

 head) averaging rather darker and duller grayish, flanks 

 more olivaceous, the colors generally less clear ; length 4.75- 

 5.40, wing 2.55-2.85 (2.69), tail 2.00-2.30 (2.14), bill from 

 nostril .29-.31 (.30). depth at base .15-.16 (.15), tarsus 

 .65-.70 (.68). Nest as in V. gilvus. Eggs .73 X .51. Hab. 



