108 



webs of primaries marked with transverse spots of white. Eest of plum 

 age continuous plumbeous, inclining to pearl-gray or ashy-blue ou the 

 lower surface (where the shafts of the feathers are usually conspicuously 

 darker), and on the upper parts becoming gradually lighter toward the 

 nape, which is bluish-plumbeous, abruptly contrasted with the black of 

 the pileum. 



Young: — Pileum brownish-blaclf, bordered below by a continuous 

 nuchal collar of unvariegated ochraceous. Eest of upper parts plain 

 blackish-sepia, unbroken by any exposed white markings, and scarcely 

 relieved by the narrow faint tips of fulvous to some of the feathers. 

 Tail black, narrowly tipped with white, and crossed by four to five nar- 

 row bands of grayish-brown or mixed brown and white ; these bands 

 more regular, continuous, and almost entirely white on the under surface. 

 Lower i)arts entirely ochraceous or white, paler on the crissum, and 

 without any markings, except an occasional dusky shaft-streak here 

 and there. Auriculars black. 



Sexes alike in colors, but differing in size, as follows : — 



Male :—^\ing, 8.00-8.50 5 tail, 7^20-8.00; culmen, 0.55-O.CO 5 tarsus, 

 2.25-2.40 5 middle toe, 1.45-1.50. (Six specimens.) 



Female .-—Vi'iug, 9.50-10.00; tail, 8.60-8.80; culmen, 0.70-0.75; tar- 

 sus, 2.45-2.70 ; middle toe, 1.60-1.80. (Five specimens.) 



The principal variations noticed among the few adults before us are 

 quite trilling. The white of the lining of the wing and of the crissum 

 is usually much clouded by a fine, irregular mottling of plumbeous ; 

 but in Xo. 61,303, S , from Yeragua, there is none of this mottling, 

 while the shafts of the feathers are conspicuously black. In No. 16,573, 

 ^, Panama (Frijole), the usual blackish shaft-streaks of the lower parts 

 are almost obsolete. The plumbeous of the nape is also darker or 

 lighter in different individuals, producing thereby a variable abruptness 

 of contrast with the black of the pileum. The young plumage varies 

 more. Some are nearly pure white beneath, but a light ochraceous 

 shade is the more usual color of the lower parts. In a young male, 

 however (43,047), from Costa Rica, the entire lower parts and the 

 nuchal collar are deep tawny-ochraceous, almost rufous on the breast 

 and thighs. A young female from Costa Rica (Ko. 39,733) is strikingly 

 similar in all the details of coloration to the adult of Micrastur melano- 

 leucus, even to the markings of the tail. The general form and the size, 

 also, are so similar to the adult male of that bird that the generic 

 characters only are different. 



List of specimens in Untied States Xaiional Museum. 



^ 





6 



7a 













'A 





a 



■^ 



a) 



c 



s 





? 





P-" 











u 



iS 











^ 



16573 





s. 



35182' .... 



s. 



39733 



166 



M. 



43047 



17 



i\r. 



47363 





M. 



62127 3704 



s. 



66333 1 11 



s. 



67868.... 



s. 



Locality. 



When col- 

 lected. 



cT ad.| Panama Railroad | 



9 j San Jos6, Costa Kica..| Sept. 4, 18G4 



9JQV. Costa Rica | Nov. — , 1863 



d'jnv.i Costa Rica (Turrialba); July 17, 1866 



' Costa Rica. j July 30, 1866 



Chiriqua 



Lijiuiio, Costa Rica 



do 



d ad, 

 d ad. 

 cfjuv. 

 ? ad. 



From whom received. 



McL 



Carmiol 



A. von Frantzius . 



J. Cooper 



Caimiol 



O. Salviu 



W. M. Gabb 



....do 



Oilier specimens examined. — Mus. Phila. Acad., 5 ; Boston Soc, 2; G. N. Lawrence, 5; 

 American Mus., N. 1., 1. Total, 21. 



