File:The bird, its form and function (1906) (14755260092).jpg

Identifier: birditsformfunct07beeb (find matches)
Title: The bird, its form and function
Year: 1906 (1900s)
Authors: Beebe, William, 1877-1962
Subjects: Birds Birds
Publisher: New York : Henry Holt
Contributing Library: Internet Archive
Digitizing Sponsor: Internet Archive

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e lower back-boned animalswe realize that a shoulder-girdle of bones is of no usewithout a limb. Therefore we find the first hint of theshoulder-girdle in sharks, in which we also find the firstlimbs, or fins. In these fishes it is nothing but a singlebar of soft cartilage. In the girdle supporting the pec-toral fin of such a fish as the trout or other bony fish,we find the adumbration of some of our birds bones.When we remember how very wing-like is the movementof a fin in the water, we will not be surprised to learnthat the girdle is almost all epiclavicle; these bonesbeing the forerunners of clavicles, and giving place, inthe higher forms, to the real wish-bones which steadilyincrease in size and importance. We would hardly The Framework of the Bird 87 recognize in these primitive types the wish-bone of ourChristmas turkey. In terrestrial quadrupeds and birds we usually findthe front limbs near the front part of the body and thehind limbs much farther back, but it is interesting to
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Fig. 61.—Girdle of a bony fish. notice that in the fish, Fig. 61, all four limbs or fins arevery far forward, almost or quite in the head regionitself. This is a result of the function of balance whichthese structures almost wholly perform, the fin of thetail furnishing the locomotive power. It is very interesting to notice how many bones havekept to their respective places in the evolution of animals, 88 The Bird no matter how much change has occurred in theirshape and size. Take, for instance, the shoulder-blades.When a tiger crouches they are very conspicuous, andwhether we take a frog, a turtle, a lizard, an armadillo,a mouse, or a horse, we may always be sure of finding ascapula in the region where we have observed it in thebird. This is an important fact, and one which makesthe identification of many bones an easy matter. Thigh-girdle The shoulder-girdle which we have just examinedwas not joined to the back-bone, but only saddled onthe ribs, the scapula extending backward, jus

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