POLIO AETUS ICHTHYAETFS. 
73 
ancl bluish fleshy at gape ; cere above leaden, at lower edge bluish ; legs and feet fleshy white, with a bluish tinge ; 
claws black. 
Entire head, upper part of hind neck, and throat cinereous ashy, the crown and nape shaded with brown ; back, rump, 
scapulars, and wings dark wood-brown, passing on the interscapular region into a paler shade, which blends above 
into the grey of the neck; in old birds the latter part is especially pale, and sometimes has the feathers edged 
light : primaries dull black; secondaries blackish brown, the inner webs somewhat cinereous; chest, breast, and 
upper flanks light wood-brown, blending into the grey of the throat ; abdomen, lower flanks, thighs, under tail- 
coverts, and tail white, terminal portion (from 1 j to 2J inches) of tail black; lesser under wing-coverts umber- 
brown. When freshly acquired, the hues of the ripper surface are much darker than when the bird is in old- 
feather, in which state the breast fades considerably, becoming a light chocolate-brown. The chin is wdiitish in 
some birds, probably those which have for the first tune acquired the adult plumage. 
Young. In the bird of the year the iris is hazel-brown ; bill and legs much as in the adult. 
The nestling is covered with white down. 
On becoming fully plumaged at about four months’ old, the upper part of the forehead, crown, hind neck, and inter- 
scapular region are light chocolate-brown, deepening slightly on the scapulars, back, and wing-coverts ; edge of 
forehead, throat, face, and above the eye, together with the tips and centres of the head and hind-neck feathers, 
and the tips only of those of the lower part of the neck, buffy white ; tips of the back, scapulars, and wing-covert 
feathers fulvous-grey, passing with a tawny hue into the brown ; quills blackish brown, all but the longer primaries 
and the secondaries tipped with the fulvous hue ; the primaries, secondaries, and greater wing-coverts crossed on their 
inner webs with light bars, paling into whitish at the inner edges ; tail brown, tipped with fulvous, paling beneath 
the coverts into whitish, and mottled, except on the bars, with fulvous ; a broad, blackish, terminal band, preceded 
by a narrow undefined bar of the same, on the central feathers only. 
Lower part of fore neck, chest, flanks, and breast more or less pale tan-brown, with shaft-stripes and tips of fulvous 
grey, which are usually broadest on the chest ; bases of the chest-feathers dark brown ; abdomen and thigh-covert 
feathers white, mottled at the tips and terminal margins with the pale hue of the lower breast; under tail-coverts 
faintly washed with the same ; under surface of tail at its base white, mottled towards the terminal band with grey : 
lesser under wing-coverts light tawny fulvous; greater series white, barred with black; axillaries pale tawny, 
marked across the centres of the feathers with brown and white. 
At the end of the first year the plumage fades, sometimes to an extraordinary degree, the chest and bream, becoming 
whitish, merely w ashed about the margins of the feathers with very pale tawny grey ; on lifting up he feathers 
of the chest the brown bases are found in their original state ; the upper surface does not undergo such a change, 
except that the light tippings, by reason of abrasion, are less conspicuous ; the tail, however, becomes considei nly 
paler than in the freshly- plumaged yearling. The adult plumage, as far as I can ascertain, is not put on i.nti- 
after the second moult. 
Obs. In my notes on “ Ceylonese Ornithology and Oology ” (loc. cit.) I pointed out that Ceylon examples of this Eish- 
Eagle were, as a constant rule, smaller than those from other places. An examination of specimens in the 
National collection from the Malay region, and a perusal of the dimensions given of late in various articles in 
‘ Stray Leathers, ’ confirms the opinion that our bird constitutes a small race of P. ichthyaetus of Java. This lattei 
is not invariably a larger bird than the Ceylonese, as I have examined a specimen from Sumatra with a wing ol 
17-7 inches, and that of another collected by Mr. Armstrong in the Eangoon district measures only 18-2 ; on the 
other hand the type specimen from Java in the British Museum measures 20 - 0, and an immature b' rd, presumably 
a female, so young that it could not he sexed, shot by Mr. Oates in Burmah, had the wing as large as 19 - 0, both 
of which latter dimensions I have never known attained to in the Ceylon bird. The Javan bird has a less cinereous 
brown hue, both above and beneath, than several that I have examined from other places ; but this s a worthless 
character, as the brown tints are variable in the Ceylon bird, depending entirely on the age of the fe her. 
As regards the position of this Eagle among its congeners, I have not placed it with the Ospreys, as Mr. Sharpe ha, 
done in his ‘ Catalogue,’ but kept it in its hitherto accepted position among the Sea-Eagles. It differs structurally 
from the Osprey in having two foramina in the sternum, the posterior edge of which is devoid of the tolerably 
deep notches existing in that of Pandion, and in not having the keel, which is also much shallower, prolonged 
to the edge ; the sternum is likewise weak, narrow', and more angulated than in the Osprey ; the feathers do not 
want the accessory plumule, and the bony protection or brow above the eye, which does not exist in the Osprey, 
is present in this genus as in all other Eaptors. In the structure of the foot, the outer toe of which is partially 
reversible, and also in the rounded claws, Polioaetus has some affinities with Pandion ■ but it differs again in its 
much shorter wings and the habits consequent on this structure. 
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