"Adult.--Upper surface of body, wings, and tail, glossy brown, the feathers mesially shaded with a darker tint, many of the feathers of the interscapular region, back, scapulars, and shoulders margined with white; primaries blackish brown, black at the tip past the notch, the inner web becoming white on the margin toward the base, some showing remains of brown bars; a few of the inner primaries, some of the adjacent secondaries and wing-coverts, narrowly margined with buffy white; under surface of the wings white, the outer series of the under coverts blotched with brown; feathers along the outer margin of the wing from elbow to base of primaries, dark brown margined with white, under surface of the secondaries and of the primaries past the notch ashy brown, the basal marginal portion of the inner webs white, barred down the center portion with brown; head, throat, and back of the neck white, a few feathers on the nape having a streak of blackish brown down the center; lores blackish lead-color; ear-coverts blackish brown, which color extends on to the sides of the neck, where the feathers are brown margined with white; chest, breast, and lower part of hind neck white, much mottled with brown on the tips of the feathers, and occasionally centered with a blackish stripe; the remainder of the under surface, thighs, and tail-coverts white; tail above brown, feathers narrowly margined at the tips with white, the inner webs of a lighter brown, all except the two center quills broadly margined and toothed with white toward the base; under surface of tail ashy white, tips of the feathers ashy margined with white. Bill black; legs and feet lead-blue; iris yellow. Length, 760; wing, 508; tail, 228; tarsus, 63; bill, 43; [27] from nostril, 30; culmen, 49. "Observation.--In some specimens, apparently fully adult, the whole of breast, chest, and sides of the neck are strongly mottled with brown, and the feathers centered with a blackish stripe; the under wing-coverts are barred with brown; the scapulars, upper wing-coverts, and quills scarcely if at all margined with white; in others the whole of the head and neck, except the ear-coverts and sides of the neck immediately behind them, is white, without any brown markings, and the dull brown of the chest takes no definite form, but is for the most part darkest on the center of the feathers." (North.) Genus POLIOAËTUS Kaup, 1847. Bill decidedly compressed, width of upper mandible at nostril less than its depth; primaries obliquely and slightly cut on inner web and exceeding secondaries by less than tarsus; back of tarsus smooth with plate divisions obsolete. 205. POLIOAËTUS ICHTHYÆTUS (Horsfield). GRAY-HEADED FISH EAGLE.