File:Key to North American birds. Containing a concise account of every species of living and fossil bird at present known from the continent north of the Mexican and United States boundary, inclusive of (14728240396).jpg

Identifier: keytonorthameric00coue (find matches)
Title: Key to North American birds. Containing a concise account of every species of living and fossil bird at present known from the continent north of the Mexican and United States boundary, inclusive of Greenland and lower California, with which are incorporated General ornithology: an outline of the structure and classification of birds; and Field ornithology, a manual of collecting, preparing, and preserving birds
Year: 1890 (1890s)
Authors: Coues, Elliott, 1842-1899
Subjects: Birds -- North America Birds -- Collection and preservation
Publisher: Boston, Estes and Lauriat
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: Biodiversity Heritage Library

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. Drawn by Dr. R. W. Shufeldt, U. S. A.,after Owen. The Axial Skeleton (figs. 54, 55, 56) of a bird or any vertebrated anhnal, that is, onehaving a back-bone, exhibits in cross-section two rings or hoops, one above and the otherbelow a central point, like the upper and lower loops of a figure 8- The upper ring is theneural arch (Gr. vevpov, neuron, a nerve), so called because such a cylinder encloses a sectionof the cerebro-spinal axis, or principal nervous system of a vertebrate (brain and spinal conl, 136 GENERAL ORNITHOLOGY. whence arise all the nerves of the body, excepting those of the sympathetic nervous system).The lower ring is the hcemal arch (Gr. ai/ia, liaima, blood), which similarly contains a sectionof the principal blood-vessels and viscera. Fig. 55 shows siidi a section, made across thethoracic or chest-region of the trunk. Here the upper ring (neural) is contracted, only sur-rounding the slender spinal cord, while the lower ring is expanded to enclose tlie licart and ^
Text Appearing After Image:
■s S o. t lungs. Such a section, made in the region of the skull, would show the reverse; the upperring greatly inflated to contain the brain, the lower contracted and otherwise greatly modifiedinto bones of the jaws. Thus the trunk of a vertebrate is a double-barrelled tube ; one tubeabove for the nervous system, the other below for the viscera at large ; the partition betweenthe two being a jointed chain of solid bones from one end of the body to the other. Thesesolid bones are the centrums or bodies of vertebrae, in the trunk; and in the head certain THE ANATOMY OF BIIWS. — OSTEOLOGY. 137 boues which in some respects correspmid with the centrums of vertebrae. The entire chain orseries of vertebrae composes the back-bone or spinal column; with its connections (thorax andpelvis) and anterior continuation (skull) it is the axial skeleton. The skull is considered bysome competent anatomists to consist of modified vertebrje. The skull-bones have certainlythe position and relations o

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