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 scutellæ, 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 extremes in the details of their external structure; but these variations I consider 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. icthyætus, 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 scutellæ nearly as well developed and continuous as in Buteo. The last of these species has the claws nearly uniform in size, and contracted and rounded underneath almost as much as in Pandion; but the other species are less so, each 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. pelagicus shows an approach to the Old World Vultures.
About nine species are known, of which only two belong to North America, one of them (H. leucocephalus) being peculiar to that continent. Tropical America is without a single representation of the genus. The majority of the species belong to the Indian region, only the H. albicilla and H. pelagicus belonging to the Palæarctic Realm, the former representing the western, and the latter peculiar to the eastern, district of that zoögeographical 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 Polioaëtus are almost precisely like Pandion in their habits.
52509,♀ ? ¼
9128,♀. ¼
9128,♀. ¼
