NATURAL SCIENCES OF PHILADELPHIA. 99 



1844, 123; Contr. Orn. 1850, 75. Bon. Consp. I., 1850, Vt.Buteo 

 albieauda, Less, Traite, 1831, 81, pi. 15. Pucheran, R. et M. Zool. 

 1850, 214. Buteo tricolor, Kuril., Ind. Azara, 1841, 1 (not of D'Orb.). 



Habitat. The whole of Middle America, north to Mirador (on 

 the eastern side), Colima (west coast) and the City of Mexico 

 (central plateau); eastern South America as far as Paraguay. 



Diagnosis. Wing, 14.50-18.00; tail, 1. 70-10.50; culmen, .95- 

 1.05; tarsus, 3.30-3.70; middle toe, 1.55-1.80. Form: Third quill 

 longest; first intermediate between sixth and eighth. Tail even in 

 adult, slightly rounded in young. Color: Adult, tail white (the 

 lateral feathers much tinged with ash), crossed by a broad subter- 

 rninal band of black; the white portion crossed by faint lines or 

 narrow bars of plumbeous. Above dark plumbeous; rump and 

 lower parts pure white; throat plumbeous-black, or bluish-plum- 

 beous. Flanks, rump, and lining of the wing usually faintlj' barred 

 with ashy, dusky, or rufous. %: Lesser wing-coverts with a re- 

 stricted patch of rufous on the anterior portion; longer scapulars 

 strongly tinged with rufous. 9: Rufous patch on lesser wing- 

 covert region extended over nearly the whole of its area; longer 

 scapulars scarcely tinged with rufous. Young: Tail hoary grayish 

 (the inner webs mostly white), growing gradually darker termin- 

 ally, and passing narrowly into dull whitish or rufous at tip; 

 crossed with numerous narrow and very obscure bars of darker, 

 these growing gradually obsolete towards the base. 1 General 

 color brownish-black, the lower parts more or less variegated 

 (most conspicuously on the posterior portions, and on middle of 

 the breast) with ochraceous or whitish. 



Remarks. The identity of specimens of the two plumages de- 

 scribed in the diagnosis as " adult" and " young" is proven by 

 specimens in which part of the tail feathers are of one plumage 

 and part of the other. Such a specimen is in Mr. Lawrence's col- 

 lection from the city of Mexico. 



The older individuals in the immature dress are colored as 

 follows : Tail hoary ash, growing darker terminally, and passing 

 narrowly into brownish-white at the tip the inner webs mostly 

 white; the terminal half with just descernible obscure bars of 

 darker, these becoming gradually obsolete on the basal half; 

 sometimes they are entirely obsolete for the full length of the 

 outer webs. Upper tail-coverts pure white, usually immaculate, 



1 These bars are sometimes entirely obsolete on the outer webs. 



