156 
Gen. LXXV. ROSTRHAMUS Less. (1830). , 
Type by monotypy R. niger Less. =Herpetotheres sociabilis Vieill. 
Head not crested ; bill long and slender, the upper 
mandible hooked, the cutting edges not festooned ; 
nostrils narrow ovals, horizontal; tail about half 
as long as wing, nearly even. Size moderate. 
251. Rostrhamus sociabilis sociabilis (Vieill.), S. America from 
N.D., xviii., p. 318 (1817). [S. America: Argentina and 
Corrientes et Rio de la Plata.] Peru to 
Southern Everglade Kite. Colombia. 
[ =R. leucopygus (Spix.)]. 
Wing ad. 325-345 mm.; entirely slaty 
black, with a brownish shade on wings ; 
base of tail and upper and under coverts 
white ; rest of tail black, with subterminal 
and subbasal brown borders, the tips 
white ; bill black; cere and feet yellow. 
725la. Rostrhamus sociabilis plumbeus Ridgway,in Florida, Cuba, 
Baird, Brewer & Ridgway, Hist. N. Amer. E. Mexico 
Birds, iii, p. 209 (1874). [Everglades, Central 
Florida. | America. 
Northern Everglade Kite. 
Larger; wing ad. 348-368 mm.; above 
paler ; head and throat more plumbeous ; 
vent paler, more brownish. 
Gen. LXXVI. HELICOLESTES Bangs & Penard (Bull. M.C.Z., 
Ixii., p. 38, 1918). 
Type by orig. desig. Falco hamatus Illig. 
Bill longer and more slender; upper mandible 
hooked almost to a sickle shape. 
252. Helicolestes hamatus (Iliger) in Temm., Pl. N. Brazil, 
Col., i., livr. 2, pl. 61, 231 (June, 1821). Colombia, 
(Brazil, type in Leyden Mus.] Dutch Guiana. 
Slender-billed Kite. 
[R. teniurus Cab. =juv.] 
