NATURAL SCIENCES OF PHILADELPHIA. 491 



[Plumbeous pfiase.] 



? Sparvius gilvicollis, Vieill., Nouv. Diet. N. H. X, 1817, 323 (adult) - 



Enc. Meth. Ill, 1264. Pucheran, Rev. Zool. 1850, 91. 



Micrastur gilvicollis, Pelz., Orn. Bras. 399 ; Orn. Nov. 1865, 10. 

 Micrastur leucauchen, Bonap., Consp. I, 1850, 30. Strickl., Orn. Syn. I, 



1855, 123 ; Scl. and Salviu, P. Z. S. 1869, 367 (excl. syn.), [adult!] 



Ridgway, Pr. Boston Soc. Nat. Hist. XVI, May, 1873, 80 [young]. 



Accipiter leucauchen, Graj r , List B, Brit. Mus. 68. Cassin, Pr. Ac. 



Nat. Sci. Philada. 1848, 88. 

 ? Falco trifasciatus, Natterer, Cat. Msc. No. 954 (fide Pelzeln). 



Falco concentricus, Pucheran. 

 Micrastur ruficollis, Sharpe, Cat. Ace. Br. Mus. 1874, 76 (part). 



Hab. Eastern South America. 



Sp. Char. Wing, 6.60-7.10; tail, 7.30-7.80; tarsus, 2.30-2.45 ; 

 middle toe, 1.15-1.30. 



Adult. Plumbeous phase : Above light plumbeous, or bluish 

 ash-gray, the wings browner ; tail slate-black, narrowly tipped 

 with white, and crossed by three narrow bars of white. Throat 

 and jugulum very light grayish, the former nearby white centrally, 

 and the latter more or less washed with light rufous. Other 

 lower parts white, everywhere finely barred with narrow and very 

 regular ra3's of plumbeous. Bill black, the basal half of the lower 

 mandible light yellowish. Rufous phase : Above rusty-brown, 

 inclining to rufous ; crown ash-gray or plumbeous, usually in 

 abrupt contrast; neck and entire jugulum light rufous; other 

 lower parts everywhere transversely barred with dusky plumbeous 

 and white. Tail blackish-dusky, narrowly tipped with white, and 

 crossed by 3-4 narrow bars of white, these sometimes obsolete on 

 outer webs. 



Young. Plumbeous phase (= M. leucauchen, Ridgway, I. c.) : 

 Above varying from grayish-brown to umber, interrupted by a 

 more or less conspicuous nuchal collar of whitish spots ; tail 

 blackish-dusky, narrowly tipped with white, and crossed by 5-7 

 rows of interrupted transverse spots of the same. Throat white, 

 sending up a conspicuous branch, in the form of a half crescent, 

 behind the brownish ear-coverts. Beneath white, more or less 

 tinged with buff; the breast sometimes washed with light rufous, 

 the whole surface (except throat and anal region) narrowly barred 

 with blackish, the bars growing fainter on the breast. Rufous 

 phase (= Falco leucauchen, Temminck ?) : Above varying from 

 dark rufous to dusky chocolate ; crown darker and more slaty. 



