FALCONID^ — THE FALCONS. 



321 



and rounded underneath almost as much as in Pandion ; but the other spe- 

 cies are less so, eacli differing in this respect, so that I consider this as only 

 indicating the greatest perfection in the specialization of the piscatorial type 

 of modified structure. In the possession of fourteen tail-feathers, its very 

 large bill, naked lores, and general aspect, the H. pelagicics shows an ap- 

 proach to the Old World Vultures.' 



About nine species are known, of which only two belong to North Amer- 

 ica, one of them (^R. leucocephalus) being peculiar to that continent. Tropical 



52509:9128. Haliaitus leucocephalus. 



28100. H. pelagicus. 



America is without a single representation of the genus. The majority of 

 the species belong to the Indian region, only the If. alhicilla and H. pelagicus 

 belonging to the Palsearctic Realm, the former representing the western, and 

 the latter peculiar to the eastern, district of that zoogeographical division ; it 

 is the former which straggles into the Nearctic fauna. The habits of the 

 Sea Eagles differ considerably from those of the true Eagles {Aquila) in very 

 important respects ; they frequent the shores of the sea, lakes, or large rivers, 

 instead of mountainous portions, and feed chiefly — some of the species 

 entirely — on fish. Those of the subgenus Polioaetus are almost precisely 

 like Pandion in their habits. 



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VOL. III. 



