208 



NORTH AMERICAN BIRDS. 



short, about equal to middle toe, with a continuous frontal series of transverse scutellse ; 

 claws extremely long and sharp, but weakly curved ; inner edge of the middle claw 

 slightly pectinated. Tliird to fourth quills longest ; outer five with inner webs sinuated. 



53081,? 



53081,^ 



Rostrhamus sociahili.%. 



53081,9. 



The species of this genus are two in number, and are peculiar to the 

 tropical portions of America, one of them being confined to the Amazon 

 reoion, the other extendimr to Florida in one direction and Buenos Avres on 

 the other. Their nearest allies are the species Circus and Elanus, like 

 them inhabiting marshy localities, where their food is found, which consists, 

 in large part, of small moUusca. 



Species and Haces. 



Common Characters. Adult. Prevailing color plumbeous-black, or bluish- 

 plumbeous ; the tail and primaries black. Entirely concolored, or with white 

 tail-coverts. Cere and feet orange-red. Young. Spotted with blackish-brown 

 and ochraceous, the former prevailing above, the latter beneath. 



1. R. sociabilis. Tail-coverts, with terminal and basal zones of the tail, 

 white; that of the tail more or less shaded with grayish-brown. Adult. 

 Uniform blackish-plumbeous, darker on the head, quills, and tail. Huh. 

 South America, West Indies, and Florida. 



Plumbeous of a glaucous cast, the head dark pluml^eous, and the 

 wing-coverts lighter, inclining to grayish-brown. Wing, 13.25 - 15.50; 

 tail, 6.75-8.25; bill .85- 1.04 ; tarsus, 1.70-2.40; middle toe, 1.40- 

 1.55. (2 sp. P. A. N. S.) Hab. Florida and West Indies . var. plumbeus. 



Plumbeous of a blackish cast, the head deep black, and the wing- 

 coverts not lighter, and not inclining to brownish. Wing, 12.90 - 14.00 ; 

 tail, 7.60 - 7.80 ; bill, .90 - 1.25 ; tarsus, 1.50-1.80; middle toe, 1.45- 

 1,65. Hah. South America vkv. so ciabilis} 



1 Ilostrhamus sociabilis, var. sociabilis (Vieiix.). Herpctotheres sociabilis, Vieill. Nouv. Diet. 

 Hist. Nat. XVIII, 318, 1818 ; Eiic. Meth. Ill, 1248. Rostrhamus sociabilis, D'Orb. A''oy. Am. 

 Merid. II. 73, 1835 ; Synop. Av. Mag. Zool. 1850. Gray, List B. Brit. Mus. p. 47 ; Gen. 

 and Subgen. Brit. Mus. p. 6. — Kaup, Monog. Falc. Cont. Orn. 1850, 78. — Strickl. Orn. Syn. 

 I, 136, 1855. Falco rostrham.us, Max. Beitrag. III. 182, 1830. Cijmindis Uucomigus, Si'ix, 

 Av. Bras. I, 7, pi. ii, 1824. lios/rhamus niger. Less. Tr. Orn. p. 56, 1831. 



Hab. South and Middle America, from Buenos Ayres to Eastern Mexico (Mirador). 



Localities : Guatemala (ScL. Ibis, I, 220) ; Ecuador (Sclater, 1860, 289) ; Panama (Law- 



