THALASSOAETUS. 243 
3.65, middle toe 2.95-3.50. West on cliffs near sea-shore. Eggs 2-3, 3.07 
X 2.32, plain dead white. Hab. Northern portions of eastern hemi- 
sphere, and southeastern Greenland. 
351. H. albicilla (Linn.). Gray Sea Eagle. 
a’, Adult with head and neck pure white, in abrupt contrast with color of body; 
tail-coverts also white. Young with plumage blackish, grayish brown, and 
white, without cinnamon-brown or isabella-color. Adult: Head, neck, tail- 
coverts, and tail entirely white; rest of plumage dusky grayish brown, varying 
to brownish black (the margins of the feathers usually paler). Immature (sec- 
ond or third year) : Head and neck blackish, the lanceolate feathers of hind- 
neck tipped with pale brownish, all the feathers pure white beneath surface ; 
upper parts mixed grayish brown and blackish, usually with more or less 
admixture of whitish ; tail blackish, the inner webs of feathers more or less 
blotched or “spattered” with whitish ; lower parts mixed white and dusky, 
either color predominating, according to the individual. Young, first year : 
Whole plumage nearly uniform black, the feathers of lower parts, however, 
with their bases white, this more or less concealed in places, producing a 
somewhat spotted or blotched appearance. Downy young: Uniform sooty 
gray. Nest on tall trees, usually near lakes or rivers, sometimes on cliffs. 
Male: Length 30.00-35.00, extent about 7 feet, wing 20.00-25.90, tail 11.00- 
15.25, culmen 1,85-2.25, tarsus 2.65-3.40, middle toe 2.35-2.90, hind claw 
1.68-1.90. Female: Length 34.00-43.00, extent about 7 to 8 feet, wing 
23.50-28.00, tail 12.50-16.00, culmen 1.90-2.35, tarsus 3.25-3.70, middle toe 
2.55-3.10, hind claw 1.60-2.00. West usually on large trees. Eggs 2-3, 2.90 
> 2.27, plain white. Hab. Whole of North America, and across Aleutian 
chain to Commander Islands, Kamtschatka. 
352. H. leucocephalus (Linn.). Bald Eagle. 
Genus THALASSOAETUS Kaur. (Page 223, pl. LXXI., fig. 2.) 
Species. 
Adult: General color dark grayish brown, the forehead, lesser and middle wing- 
coverts, thighs, rump, tail-coverts, and tail, pure white ; lanceolate feathers of hind- 
neck pale grayish brown, with lighter edges; bill, cere, and feet intense yellow in 
life; iris pale yellow. Young: Entirely dusky brownish, or with more or less ad- 
mixture of white, according to age, on those portions which are white in adult; 
bill more or less obscured with dusky. Male: Length 37.60-38.00, extent 87.50, 
wing 23.25, tail 13.60 (graduated for 4.10), culmen 2.45. Female: Length about 
41.00, extent 93.00, wing 24.00-26.00, tail 14.25, culmen 2.60-2.75, hind claw 1.95. 
Downy young: Uniform smoky brownish gray. Hab. Sea-coasts and larger rivers 
of Kamtschatka and borders of Okhotsk Sea, south, in winter, to Japan; occasional 
24 in Aleutian Islands? 
eraccidental in > T. pelagicus (PaLu.). Kamtschatkan Sea Eagle.’ 
1 Thalassoaétus Kavp, Class. Siug. Vig. 1844, 123. Type, Aquila pelagica PALL. 
2 Aquila pelagica PauL., Zoog. Rosso-As. i. 1826, 343, ph. 1. Thalassoadtue pelagicus Kaur, Mus. Senck, 
iii, 1846, 261. 
