Title: The animal kingdom, arranged after its organization, forming a natural history of animals, and an introduction to comparative anatomy
Identifier: animalkingdom00cuvi (find matches)
Year: 1854 (1850s)
Authors: Cuvier, Georges, baron, 1769-1832; Blyth, Edward, 1810-1873; Mudie, Robert, 1777-1842; Johnston, George, 1797-1855; Westwood, J. O. (John Obadiah), 1805-1893; Carpenter, William Benjamin, 1813-1885
Subjects: Zoology
Publisher: London, W. S. Orr and co.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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154 AVES. Many of the cold-blooded Ovipara do not bring forth their young until they are developed and extricated from their shell, or other membranes which separated them from their parent. These are called false Ovipara. THE SECOND CLASS OF VERTEBRATED ANIMALS. THE BIRDS (AVES),— Are oviparous vertebrates with double circulation and respiration, (mostly) organized for flight. Their lungs, undivided and attached to the ribs, are enveloped by a membrane pierced with large holes, and which allows the air to pass into many cavities of the chest, the abdominal region, arm-pits, and even of the interior of the bones* ; so that the ambient fluid not only bathes the surface of the pulmonary vessels, but also that of an infinitude of vessels traversing the rest of the body. Thus Birds respire, in certain respects, by the ramifications of their aorta, as well as by those of their pulmonary artery, and the energy of their irritability is in proportion to their amount of respiration.f Their total conformation is arranged to participate in this energy. Their anterior extremities, destined to sustain them in flight, could neither serve them for standing, nor for clutching : they are bipeds, then, and pick up objects from the earth with their mouth ; their body, consequently, is balanced upon the legs ; the thighs are directed forward, and the toes are lengthened to form a sufficient base for standing. The pelvis is longitudi- nally much extended, to furnish attachment to the muscles which support the trunk upon the thighs : there is even a suite of muscles proceeding from the pelvis to the toes ; and passing over the knee and heel, so that the simple weight of the bird flexes the toes : it is thus that they are enabled to sleep perched on one foot. The ischia, and especially the ossa pubis, are lengthened out behind, and widened in their span, to allow the necessary space for the developement of the eggs. The neck and the beak are elongated to reach the ground; but the former has also the requisite flexibility for doubling backward when at rest. It has therefore numerous vertebra?, (varying from twelve to twenty-three, which latter number is attained only in the genus Cy gnus'). The trunk, on the contrary, which serves as a fulcrum to the wings, has but little mobility; the sternum especially, to which Fig. er.-sueicton of Jcr Falcon. are attached the muscles which effect the propulsive stroke in flying, is of great extent, its surface (except in the Ostrich and allied genera, which do not fly,) being further augmented by a projecting ridge along its middle. It is (mostly)
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* In the Hornbills, even the phalanges of the toes are hollow, and communicate with the lungs. The opposite extreme occurs in the Apteryx, which has no accessory air-cavities.—Ed. t Two Sparrows consume as much air as a Guinea-pig-..—Lavoi- sieb, Memuires de Chimie, i. 110.

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