. 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 . corre- islandica), inlated and economized. This latter mechanism is further illustrated in fig. 28,where re and mc show respectively the size, shape and position of the radial con-
. 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 . corre- islandica), inlated and economized. This latter mechanism is further illustrated in fig. 28,where re and mc show respectively the size, shape and position of the radial con-dyle and ulnar condyle of the humerus. It is evident that in the flexed state ofthe elbow, as shown in the middle figure, the radius, rd, is so pushed upon thatits end projects beyond ul, the ulna; while in the opposite condition of extension,shown in the lower figure, rd is pulled back to a corresponding extent,which alone forms the first segment of the wing. In the closed wing, the humerus lies nearlyin the position of the same bone in man when the elbow is against the body; in extensionof the wing, the elbow is borne away from the body, as when we raise the arm, but carry itneither forward nor backward. A peculiarity of the birds humerus is, that it is rotated on its which thereare eleven. The upper arm-bone,h, reaching from shoulder Ato elbow B, is the humerus, EXTERNAL PARTS OF BIRDS. —THE WINGS. 113. axis through about the quadrant of a circle, so that what is the front of the human bone is the outer aspect in a bird. The humerus is a cylindric bone, straightish or somewhat italic /-shaped, with a globular head to fit the socket of the shoulder, a strong pectoral ridge for insertion of breast muscles, and at the lower end two condyles (fig. 28, re, uc), or surfaces for articulation with a pair of succeeding bones. The second segment is the fore-arm, ciihit or antibra- chium, extending from elbow to wrist, B to C, fig. 27; this has two parallel bones of about equal lengt
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Keywords: ., bo, bookcentury1800, bookdecade1890, booksubjectbirdsnorthamerica
