180 BULLETIN 50, UNITED STATES NATIONAL MtTSECTM. 



/. Tipper parts more olivaceous, sides and flanks olive-yellowish; tail 

 shorter (41.5-48). 

 g. Back distinctly olive, nearly conoolor with rump and upper tail- 

 coverts; sides and flanks deeper olive-yellow; under tail-coverts 

 sulphur yellow; tail 41.5^7. (Nebraska to Illinois and southward 

 into northeastern Mexico; in winter south to Oaxaca.) 



Vireo bellii bellii, adults (p. 204) 

 gg. Back grayish olive distinctly less bright than rump and upper tail- 

 coverts; sides and flanks pale olive-yellow; under tail-coverts 

 yellowish white; tail 45-48. (Western Texas and southward to 



central Mexico. ) Vireo bellii medius, adults (p. 206) 



ff. Upper parts more grayish, sides and flanks pale yellowish olive or 

 merely tinged with that color; tail longer (47-54). 

 g. More strongly tinged with olive above, the sides and flanks more 

 strongly tinged with yellowish olive. (Extreme western portion 

 of Texas to Arizona and southward into northwestern Mexico. ) 



Vireo bellii arizonae, adults (p. 207) 

 gg. Less strongly tinged with olive above, the sides and flanks faintly, 

 if at all, tinged with yellowish olive. (Central California to Cape 

 San Lucas and southwestern Nevada. ) 



Vireo bellii puaillTiB, adults (p. 208) 

 dd. Back brownish olive (contrasted with grayish brown of pileum and hind- 

 neck) or brown, like pileum and hindneck. 

 e. Pileum, hindneck, and back plain brown; sides and flanks not yellow. 

 (Young.) 

 /. Pileum, back, etc. , grayish or vinaceous, brown. 



Vireo bellii and subspecies, « young. 

 g. Pileum, back, etc., distinctly brown (between broccoli brown and 



raw umber Vireo latimeri, young (p. 210). 



ee. Pileum and hindneck grayish brown or brownish gray, in marked con- 

 trast with brownish olive of back; sides and flanks yellow (straw yel- 

 low to naples or maize yellow). (Porto Rico). 



Vireo latimeri, adults (p. 210). 



VIREO BAIRDI Ridgway. 

 BAIRB'S VIB.EO. 



Adults {sexes alihe). — Pileum and hindneck plain grayish brown 

 (hair brown, broccoli or drab), becoming more cinnamon or russet on 

 forehead, especially on lateral margins; back, scapulars, rump, upper 

 tail-coverts, and lesser wing-coverts plain, rather light, olive-brown; 

 wings (except lesser coverts) and tail dusky with pale olive edgings, 

 the middle and greater wing-coverts broadly tipped with yellowish 

 white or pale primrose yellow, producing two conspicuous bands across 

 wing, and tertials broadly edged with the same; lores and orbital ring 

 white, the latter interrupted on upper portion by a dusky space on 

 upper eyelid; auricular region, suborbital region (in part), sides of 

 neck, and sides light cinnamon, fading out and becoming more olive on 



"The young of the several forms of V. bellii differ in the same way as adults; that 

 of V. h. bellii being most deeply colored, with flanks and under tail-coverts strongly 

 yellowish, the others, in geographic sequence, becoming paler until in that of F. 6. 

 pusillus the yellow tinge to the posterior under parts is nearly if not quite wanting. 



