. 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 . finite areas. Not only are the pterijla and apteria thus definite,but their size, form, and arrangement mark whole families and even orders of birds; so thatpterylosis becomes avai
. 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 . finite areas. Not only are the pterijla and apteria thus definite,but their size, form, and arrangement mark whole families and even orders of birds; so thatpterylosis becomes available, and is indeed found to be important, for purposes of , or the description of this matter, has been made a special study by the cele-brated Nitzsch, who has laid down the general plan of pterylosis which obtains in the greatmajority of birds, as follows : 1. The spinal or dorsal tract (pteryla spinalis; fig. 24, 1),running along the middle of the bird above from the nape of tlie neck to the tail; subject togreat variation in width, to dilation and contraction, to forking, to sending out branches, tointerruption, etc. 2. The humeral tracts {pt. hiiiiierales ; Lat. humerus, the shoulder, or upperarm-bone: lig. 24, 2), always present, t)ne on each wing; they are narrow bands, running fromthe shoulder obliquely backward upon the upper arm-bone, parallel with the
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbirds, bookyear1896
