320 NORTH AMERICAN BIRDS. 



{Centrocercus urophasianus), chasing her on the wing until the fugitive 

 dropped down to the ground from exhaustion, when she was picked up by 

 the foremost of the Eagles, who then flew off together to the summit of the 

 mountain range (the East Humboldt) near by, where they probably had 

 their nest. 



An egg of this bird, taken by Mr. K. MacDonald among the mountains 

 west of the Lower Mackenzie Eiver, measures 2.60 inches in length by 2.18 

 in breadth. The ground-color is of a rich pinkish cream-color, boldly dashed 

 with large blotches of three or four varying shades of umber-brown, inter- 

 mingled with a few finer markings of a lighter shade of brown, and a few 

 clouded markings of a purplish-slate. These markings are grouped and 

 confluent about the smaller end. Other specimens vary to whitish, with 

 faint obsolete blotches. 



Genus HALIAETUS, Savigny. 



HaliaefAis, Savig. 1809. (Type, Falco cdhicilla, Linn.) 



Thalassoaettis, Kaup, 1844. (Type, Fcdco pelagicus, Pallas.) ' ■ 



Cuncuma, Hodgson, 1837. (Type, Falco macei, Temm.) 



Pontoaetus, Kaup, 1844. (Same type.) 



Ptlagrus, Blas. 1849. (Same type.) 



Polioaetus, Kaup, 1847. (Type, Falco icthyaetus, Horsf. ) 



Icthyiaetus, Lafr. 1839 (nee Kaup, 1829). (Same tjrpe. ) 



Gen. Char. Form robust, and organization powerful, as in Aquila ; size large. Bill 

 very large, usually somewhat inflated, the chord of the arch of the culmen more than 

 twice the length of the cere on top ; commissure with a more or less distinct festoon and 

 sinuation behind it. Nostril oval, obliquely vertical. Feet robust and strong, the tarsus 

 less than one and a half times the middle toe ; tarsus feathered in front and on the sides 

 for about one half its length; front of the tarsus and top of the toes with an imperfectly 

 continuous series of transverse scutellae, entirely interrupted in the region of the digito- 

 tarsal joint; the other portions covered with roundish, somewhat granular, scales, these 

 larger on the posterior face. Claws large, strongly curved, and more obtuse, and less 

 graduated in size, than in Aquila. No trace of a web between outer and middle toes. 

 Wing very large, the primaries well developed and strong ; third to fifth quill longest ; 

 first longer than the ninth ; outer five to six with inner webs deeply emarginated. Tail 

 variable in length and shape, usually short and rounded, cuneate and with fourteen 

 feathers in H. pelagicus, and nearly even, and with twelve feathers, in H. macei, the rest 

 all having twelve feathers, varying in form with the .species. Feathers of the neck, all 

 round, lanceolate. 



The species of this very strongly marked genus vary between great ex- 

 tremes in the details of their external structure ; but these variations I con- 

 sider to be mainly specific, though two well-defined subgeneric divisions 

 should be made, one to include the Old World H. leucogaster, H. vocifer, 

 and H. icthymtus, which have five, instead of six, outer quills, with their 

 inner webs cut, and the tarsus with the frontal and posterior rows of broad 

 transverse scutellse nearly as well developed and continuous as in Buteo. 

 The last of these species has the claws nearly uniform in size, and contracted 



