THALASSOAETUS. 243 



3.C5, middle too 2.95-3.50. Nest on cliffs near sea-shore. Eggs 2-3, 3.07 

 X 2.32, jilain dead white. Ilab. Northern portions of eastern hemi- 

 sphere, and southeastern Greenland. 



351. H. albicilla (Linn.). Gray Sea Eagle. 

 a*. Adult with head and neck jiiiro white, in abrupt contrast with color of body; 

 tail-coverts also white. Young with plumage blackish, graj'ish brown, and 

 white, without ciniiainon-brown or isabella-color. Adult: Head, neck, tail- 

 coverts, and tail entirely white ; rest of plumage dusky grayish brown, varj-ing 

 to brownish black (the margins of the feathers usually jjaler). 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 

 admi.xture 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 soot}"- 

 gray. Kest on tall trees, usuallj- near lakes or rivers, sometimes on cliffs. 

 Jlale: 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 

 1.6S-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. Nest usually on large trees. Eggs 2-3, 2.90 

 X 2.27, plain white. Hab. AVhole of North America, and across Aleutian 

 chain to Commander Islands, Kamtschutka. 



352. H. leucocephalus (Linn.). Bald Eagle. 



Genus THALASSOAETUS Kaup.' (Page 223, pi. LXXL, fig. 2.) 

 Species. 

 Adult : General color dark grayish brown, the forehead, lesser antl 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, himl claw 1.95. 

 Downy young : Uniform smokj- brownish gray. Hah. Sea-coasts and larger rivers 

 of Kamtschatka and borders of Okhotsk Sea, south, in winter, to Japan ; occasional 



or accidental in Aleutian Islands? 



T. pelagicus (Pali..). Kamtschatkan Sea Eagle.' 



> Tkalmtoaltut Kacp, CIms. Sang. Vog. 1S44, 12.S. Type, A^iny,, ,,.h.j!rn Pai.i.. 



' AqnUn ptlagtca Pall., Zoog. Rosso-As. i. 1826, 34.S, pi. 1. ThaUttsoaltat pdayicui Kacp, Mus. Scnck. 

 iii. 1S46, 261. 



