320 NORTH AMERICAN BIRDS. 



{Ccntroccrcus urophasianm), cliasing her on the wing nntil the fugitive 

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

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

 mountain range (the East JrlumlKjldt) near by, where tiiey probably had 

 their nest. 



An egg of tliis Ijird, taken by Mr. li. ilacDonald among the mountains 

 west of the Lower ^Mackenzie Kiver, 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. 



Genu.s HALIAiJTUS, S.wigxy. 



Haliaetus, Savio. 1809. (Type, Falcu albkilla, Lixs.) 



Thalassoaetus, K.\rp, 1844. (Type, Falco pelagicits, Pallas.) 



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



Pontoaetus, K.wp, 1844. (Same type. ) 



Blagrus, Blas. 1849. (Same type.) 



Polioaetus, Kaup, 1847. (Type, Falco icthyaehin, Hop.sf. ) 



Icthi/iaetus, Lafr. 1839 (nee Kaup, 1829). (.Sume type.) 



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

 very large, usually somewhat inflated, the chord of the arch of the culraen 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 le.ss 

 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 si.x 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 //. 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 Jl. kvcogastcr, H. vocifer, 

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

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

 transverse scutellas nearly as well developed and continuous as in Butio. 

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



