100 



PROCEEDINGS OF THE ACADEMY OF 



but sometimes barred ; inner webs of primaries ashy, the two or 

 three outer ones more whitish, and sometimes barred with dusky. 

 In males, the middle of the breast, the tibiae and crissum, are usu- 

 ally ochraceous irregularly spotted with brownish-black. 



The darker-colored individuals in this stage are distinguishable 

 from the dark examples of the young of C. swainsoni only by the 

 very much stouter and longer tarsi. 



The adults vaiy but little. The white of the jugulum usually 

 reaches forward medially into the plumbeous of the throat, and in 

 one ($ ad. Tehuantepec, Mexico; Sumichrast) it extends inter- 

 ruptedly, however to the chin. Another male from the same 

 localit} T has the scapulars almost entirely rufous, with black shaft- 

 streaks. The white of the lower parts in the adult is of a pure- 

 ness and continuity strikingly characteristic of this species. 



A very young specimen from Paraguay has the tail more 

 brownish, more distinctly barred, and more ochraceous on the tip ; 

 the upper tail-coverts are ochraceous marked with broad crescentic 

 bars of blackish, and the upper parts generally are variegated 

 with ochraceous. 



Material examined. U. S. National Museum, 12; Museum of 

 the Academy of Natural Sciences of Philadelphia, 6 ; Museum of 

 G-. N. Lawrence, Esq., 1 ; other specimens, 1 4. Total number of 

 specimens examined, 23. 



Measurements. 



5. Buteo (Craxirex) Swainsoni. 



t ? ? Buteo cinereus, Vieill., Ois. Am. Sept. 1807. ''Buteo vulgaris,'''' 

 Swains. & Rich., F. B. A. II., 1831, 41, pi. 27 (adult). Jard. (ed. 

 Wils.), Am. Orn., II., 1838, 56. Brewer (ed. Wils.), Am. Orn., 303. 

 Synop., 1852, 684. Buteo swainsoni, Bonap., Comp. List., 1838, 3 ; 



1 These are specimens collected on the Isthmus of Tehuantepec, by Pro- 

 fessor F. Sumichrast, and not entered in the Register of the National 

 Museum. 



