331 
Paraguay , Bolivia, and Southern Brazil. 
Imm. $. Irides and cere lemon-yellow, orbits greener ; 
bill slate-coloured, darker at tip; legs and toes lemon- 
yellow. 
These birds agree with the remarks made by Mr. Chubb 
on the plumages of this Hawk, except that the adult female 
shot on Aug. 7th has five bars to the tail and an indication 
of a sixth. 
Commonly observed throughout the river expedition, 
sitting both on the trees and on the banks. 
178. ASTURINA N1TIDA. 
Asturina nitida Sharpe, Cat. B. i. p. 203. 
a. $ ad. Puerto Maria, Paraguay. Oct 24, 1909. 
Irides brown, orbits fleshy, cere and gape lemon-yellow ; 
bill black, inclining to slate-coloured at base; legs and toes 
dull lemon-coloured, nails black. 
179. Buteo swainsoni. 
Buteo ohsoletus (nec Gm.), Sharpe, Cat. B. i. p. 184. 
Buteo swainsoni Arg. Orn. ii. p. 59; Sharpe, Hand-1, i. 
p. 256. 
a. young. Luiconia, Ajo. Nov. 14, 1908. 
b. $ young. Los Ynglases, Ajo. Dec. 9, 1909. 
One of these two males is more thickly marked on the 
breast than the other. 
180. Urubitinga zonura. 
Urubitinga zonura Sharpe, Cat. B. i. p. 213. 
Urubitinga urubitinga Sharpe, Hand-1, i. p. 258. 
a. $ . Tayru, Paraguay. Aug. 5, 1909. 
b. $ . Villa Pilar, Paraguay. Aug. 6, 1909. 
181. Busarellus nigricollis. 
Busarellus nigricollis Sharpe, Cat. B. i. p. 211. 
a. $ . Riacho Ancho, N. Argentine. Aug. 1, 1909. 
b. $ . Near Villa Franca, Paraguay. Nov. 6, 1909. 
Irides brown ; bill black; orbits and gape slate-coloured ; 
legs and toes bluish white. 
The female from Riacho Ancho is obviously younger than 
the other, as it has the chest-feathers broadly centred with 
