. 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. Birds; Birds. THE ANATOMY OF BIBDS. —OSTEOLOGY. 135 The skeleton of birds is noted for the number and extent of its anchyloses, a great ten- dency to coossification and condensation
. 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. Birds; Birds. THE ANATOMY OF BIBDS. —OSTEOLOGY. 135 The skeleton of birds is noted for the number and extent of its anchyloses, a great ten- dency to coossification and condensation of bone-tissue resulting from the energy of the vital activities in this hot-blooded, quick-breathing class of creatures. Birds' bones are remarkably hard and compact. When growing, they are solid and marrowy, but in after life more or fewer of them become hollow and are fiUed with air. This pneumaticity (Gr. Trvev/MnKos, pneumatikos, windy) is highly characteristic of the avian skeleton. Air penetrates the skuU-bones from the nose and ear-passages, and may permeate all of them. It gains access to the bones of the trunk and limbs by means of air-tubes and air-sacs which connect with the air-passages in the lungs; such sacs, sometimes of great extent, are also found in many places in the interior of the body, beneath the skin, etc.; sometimes the whole subcutaneous tissue is pneumatic. The extent to which the skeleton is aerated is very variable. In many birds only the skull, in a few the entire skeleton, is in such condition; ordinarily the greater part of the skull,' and the lesser part of the trunk and limbs, is pneumatized. The passage of air in some cases is so free, as into the arm-bone for example, that a bird with the windpipe stopped can breathe. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Cou
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbirds, bookyear1894
