. 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 . g out the forearm at the is another essential feature in a birds wing. In the figure, 6, abcrepresents a deep angle formed by the bones, but none such is seen ujjouthe outside of the wing. This is because this triangular space is filled upby a fold of skin stretched over a cord that passes straight from near a to A and c approach or recede as the wing is folded or unfolded, and asimple cord
. 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 . g out the forearm at the is another essential feature in a birds wing. In the figure, 6, abcrepresents a deep angle formed by the bones, but none such is seen ujjouthe outside of the wing. This is because this triangular space is filled upby a fold of skin stretched over a cord that passes straight from near a to A and c approach or recede as the wing is folded or unfolded, and asimple cord long enough to reach the full distance a — c would be slack inthe folded wing; so the cord is made elastic, like an india rubber band ; itstretches when the wing is unfolded, and contracts when the wing is shut;it is thus always hauled taut. The cord makes the always straightish andsmooth anterior border of the wing. The carpus c, or the always promi-nent point of the anterior border, is a highly important landmark in de-scriptions, and should be thoroughly understood; it is also called the bendof the wing. (See under Directions for Measurement; see also explana-tion of fig. 6.). Fig. 6, taken from a young chicken (right wing, upper surface), shows the compositionana mechanism of a birds wing, a, shoulder; n, elbow; c, wrist or carpus; d, tip of prin- 32 MECHANISM OF THE WING. cipal (the third) finger; ab, arin ; bc, forearm; cd, piuion, or haud, composed of c, carpus,thence to e, metacarpus or hand proper, except the bone i, tliis, and kd, being diyits or fin-gers, a, shaft of humerus; h, ulna; c, radius; d, scapholunar bone; e, cuneiform bono;these last two composing wrist or carpus proper. Now the figure (1) marks two linesthat run to the two euds of the humerus, designating a sort of cap ou either end of that bone;tliis cap is an epiphysis;* both ends of ulna and radius show similar epiphyses, connectedin the figure, as in case of the humerus, with the shaft by u-nved li
Size: 2087px × 1197px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, bookpublishere, booksubjectbirds
