POLYBORUS.—MILVAGO. 127 
A good account of the nesting of this species in Mexico has been given by Grayson 3! 
and in Guatemala by Robert Owen 25. 
2. Polyborus pallidus. 
Polyborus audubonii (nec Cass.), Grayson, Pr. Boston Soc. Nat. Hist. xiv. p. 268". 
Polyborus tharus, var. audubonii (pt.) (nec Cass.), Lawr. Mem. Boston Soc. Nat. Hist. ii. p. 303°. 
Polyborus cheriway pallidus, Nelson, Proc. Biol. Soc. Washington, xii. p. 8°; N. Amer. Fauna, 
no. 14, p. 38°. 
Polyborus pallidus, Sharpe, Hand-l. Birds, i. p. 243°. 
P. cheriway similis, vix minor, sed ubique pallidior (teste Nelson, J. c.). 
Hab. Mexico, Tres Marias Is. (Grayson 12, Nelson? 4). 
Grayson was the first to record the presence of a Caracara on the ‘Tres Marias 
Islands1, and the specimens he obtained were referred by Lawrence? to P. cheriway, 
the species which inhabits the adjacent mainland of Central America. Mr. Nelson, 
however, has drawn attention to the differences exhibited by the insular form, and named 
it P. cheriway pallidus. He says that the bird was abundant about the settlement on 
Maria Madre, where the log-roads and dry bottoms of the cafions were favourite resorts. 
It was also found perched on tree-tops in the midst of unbroken forest, and was 
commonly distributed over the other islands, including San Juanito. Iguanas were 
very plentiful and formed the chief food, but the Caracaras readily devoured any carrion 
obtainable +. 
MILVAGO. 
Milvago, Spix, Av. Bras. i. p. 12 (1824) ; Ridgw. Bull. U. S. Geol. & Geogr. Surv. i. p. 466 
(1878). 
Ibycter, partim, Sharpe, Cat. Birds Brit. Mus. i. p. 34 (1874). 
The genus Milvago is associated with Polyborus by Mr. Ridgway, its habits being 
‘chiefly terrestrial.” The tarsus is much longer than the middle toe, but the outer 
toe is decidedly longer than the inner; the posterior one does not reach the first joint 
of the middle toe; claws sharp, as in the Falcons; posterior face of the tarsus with two 
distinct rows of quadrate scales; nostril circular, in the middle of the cere, its tubercle 
exposed ; anterior outline of the cere doubly curved; tooth and notch of the tomia of 
the bill distinctly indicated ; lower jaw normally feathered. 
Two species are known: MM. chimango, inhabiting South America from Tierra del 
Fuego to Buenos Ayres, and on the west to Peru; and IM. chimachima, extending 
over Tropical America as far north as Panama. 
1. Milvago chimachima. 
Chimachima, Azara, Apunt. i. 50°. 
Polyborus chimachima, Vieill. N. Dict. d’Hist. N. v. p. 259°. 
