"Adult.--Above black, with an occipital crest 60 mm. in length; ear-coverts somewhat mixed with whitish; cheeks, throat, and breast pure white, with a few narrow black shaft-lines on the side of the latter; rest of under surface, including under wing- and tail-coverts, tawny rufous, streaked with black shaft-stripes, rather broader on the flanks, where they are more merged; wings black, some of the feathers externally brownish, the inner lining of quills whitish ashy, with a few blackish bars on the inner web of the primaries, the secondaries narrowly tipped with white; tail black, very slightly tipped with whity brown, and with indications of brown cross-bands under certain lights, the lower surface of the tail ashy white, with a subterminal brown bar. Cere yellow; bill leaden blue; feet yellow, claws black; iris brown. Length, 533; culmen, 38; wing, 358; tail, 211; tarsus, 74." (Sharpe.) Immature male.--Upper parts earthy brown, lighter on crown, the feathers tipped with white; forehead all white; long crest-feathers blackish brown; a black patch in front of and over eye; wing-coverts like the back; primaries and secondaries blackish brown, tipped with white; tail blackish brown, tipped with white and crossed by about nine lighter bars; entire under parts, except a brown patch on each flank, pure white. Wing, 370; tail, 225; culmen from base, 35; tarsus, 69; middle toe with claw, 72. The sexes are similar in color. A male from Sibuyan measures: Wing, 340; tail, 190; culmen from base, 34; tarsus, 72. A female from northern Mindanao measures: Wing, 360; tail, 210; culmen from base, 35; tarsus, 66. Genus SPIZAËTUS Vieillot, 1816. Bill compressed; culmen rapidly curved from base to tip; edge of upper mandible sinuate; nostril large and oval; occipital crest short and slightly pointed; wings moderate, fourth or fifth quill longest; secondaries long, falling short of primaries by about length of middle toe without claw; tarsus covered to the toes with short thick-set feathers; top of toes covered with small irregular scales. Species. a1. Under parts white with bold brown markings on breast; thighs brown with fine white cross-bars. ... philippensis (p. 224) a2. Under and upper parts uniform blackish brown. ... limnæëtus (p. 225) 183. SPIZAËTUS PHILIPPENSIS Gurney. PHILIPPINE HAWK EAGLE. Spizaetus philippensis Gurney, in Gould's Birds Asia (1863), pt. 15. Spizaetus philippinensis Sharpe, Cat. Birds Brit. Mus. (1874), 1, 261 (footnote). Limnaëtus philippensis Walden, Trans. Zool. Soc. (1875), 9, pt. 2, 141, pl. 24. Spizaëtus philippinensis Sharpe, Hand-List (1899), 1, 264; McGregor and Worcester, Hand-List (1906), 42. Basilan (Steere Exp., Bourns & Worcester); Luzon (Gevers, Heriot, Whitehead); Masbate (Steere Exp.); Mindoro (Porter); Negros (Everett, Steere Exp.); Palawan (Platen); Siquijor (Bourns & Worcester).