240 On the Ornithology of Wits. 
and both are equally fierce, sullen, unsociable and solitary in their 
habits, possessed of great strength, and often of considerable 
courage: as there are herbivorous quadrupeds, so there are grani- 
yorous birds, and both of these are gentle and gregarious in their 
habits, a mild and tractable race, and easily domesticated. There 
are also birds as well as beasts of an amphibious nature, having 
organs suited to their habits, and these live chiefly in the water, and 
feed on aquatic productions: and there are many similar re- 
semblances. Like the quadrupeds too, they are warm-blooded and 
vertebrate; but unlike them, they are oviparous; and instead of 
fur, are usually clothed almost entirely with feathers ; while instead 
of fore-feet, they are furnished with wings: and we shall presently 
see that there are many other striking points of difference in struc- 
ture between them. Unlike the heavy bodies of the Mammalia, 
which are formed to live on the surface of the earth, the bodies of 
the birds are light and buoyant. They each possess externally head, 
neck, body, tail, legs and feet; but instead of the large head, the 
heavy neck, the deep chest, the wide shoulder, and the sinewy legs 
of the quadrupeds, the observant Bewick bids us note “the pointed 
beak, the long and pliant neck, the gently swelling shoulder, the 
expansive wings, the tapering tail, the light and bony feet of birds:” 
every one of these seem formed to combine, as far as possible, the 
least weight with the greatest strength: there is no superfluous 
bulk in the structure of a bird: compared with its dimensions, and 
the width of its expanded wings, how trifling and insignificant a 
proportion does the body seem to occupy: how every part seems to 
conduce towards lightness and buoyancy. The plumage too with 
which they are clothed is soft and delicate, and yet so close and 
thick as to form an admirable protection against the intense cold of 
the atmosphere through which they wing their way, and to which 
their swift movements must necessarily expose them: the feathers 
which compose it are attached to the skin, somewhat after the 
manner of hair, and are periodically moulted or changed, and 
nothing can exceed the beauty, and often brilliancy of their colouring, 
as nothing can be conceived more adapted to combine the two objects 
of extreme warmth and excessive lightness. With such an airy 
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