52 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



HYLOCICHLA USTULATA USTULATA (Nuttall). 

 RUSSET-BACKED THRUSH. 



Adults in spring and summer. — Above plain olive-brown (varying 

 from nearly hair brown to between broccoli brown and raw-umber) ; « 

 a conspicuous orbital ring and loral region pale buff, the latter more 

 or less obscured with olive-brownish, especially near central portion; 

 auricular region olive-brown, with narrow shaft-streaks of pale buff 

 or buffy wliitish; malar region buffy, more or less distinctly streaked 

 or suffused with olive-brownish; chin, tlu-oat, and chest buff (more or 

 less deep), the chin and throat sometimes buffy white, the sides of 

 lower throat and whole chest with triangular marks of deep olive- 

 brown, these markings narrower and more wedge-shaped anteriorly, 

 broader posteriorly, those on middle or central portion of chest 

 darker, sometimes approaching a sooty hue; a submalar streak of 

 olive-brown along each side of tliroat; breast, abdomen, and under 

 tail-coverts white, the upper portion of the first (especially on lateral 

 portions) transversely spotted with light olive-brown; sides and 

 flanks pale olive-brown or broccoli brown; axillars pale olive-brown- 

 ish, narrowly tipped with paler and becoming paler and more buffy 

 basally; under wing-coverts pale buffy, suffused with pale brownish; 

 bill dusky brown or blackish, the basal half (approximately) of man- 

 dible pale (pale dull fleshy or lilaceous in life); iris deep brown; legs 

 and feet pale brownish (in dried skins) . 



Adults in autumn and winter. — Similar to the spring and summer 

 plumage, but more deeply or brightly colored, the brown of upper 

 parts varying from olive-brown to russet-brown,'' buff of anterior 

 under parts deeper, and under tail-coverts tinged with buff. 



Young. — Above olive-brown, the remiges and rectrices as in adults, 

 but pileum, hindneck, back, scapulars, and lesser wing-coverts 

 streaked with buff, rump and upper tail-coverts indistinctly streaked 

 or spotted with pale tawny, the middle and greater wing-coverts 

 tipped (more or less distinctly) with buff or pale tawny; under parts 

 much as in adults, but markings all distinctly transverse, except 

 (sometimes) on extreme upper chest and sides of lower throat, the 

 sides, and flanks (sometimes also lower breast and sides of abdomen) 

 barred or transversely spotted with olive-brown or dusky; under 

 tail-coverts pale grayish buffy. 



Adult male. —hangth (skins), 161-185 (173); wing, 93-103.5 (97.8); 

 tail, 67-79.5 (73); exposed culmen, 13-15 (13.9); tarsus, 27-31 

 (28.2); middle toe, 16-18.5 (17.4).^^ 



o I find, after examination of a very large series of specimens, that the variation in 

 color is not at all geographical, the extremes occurring together, even during the 

 breeding season. 



b Between raw-uml)er and russet of Ridgway's Nomenclature of Colors. 



c Thirty-four specimens. 



