. Elementary biology, animal and human. Biology. BIRDS 65 alone would seem to necessitate many and varied instru- ments : yet all this is made possible, and chiefly executed, by one small portion of the bird — its bill or ; ^ While the size and shape of the bill varies greatly in differ- ent kinds of birds, it always consists of two parts (mandibles) (Fig. 46), which correspond in position to the upper and lower jaws of man. When the bill is opened, a careful ex- amination shows that a bird has no teeth. Some of the birds that lived ages ago, however, had well-developed teeth in thei
. Elementary biology, animal and human. Biology. BIRDS 65 alone would seem to necessitate many and varied instru- ments : yet all this is made possible, and chiefly executed, by one small portion of the bird — its bill or ; ^ While the size and shape of the bill varies greatly in differ- ent kinds of birds, it always consists of two parts (mandibles) (Fig. 46), which correspond in position to the upper and lower jaws of man. When the bill is opened, a careful ex- amination shows that a bird has no teeth. Some of the birds that lived ages ago, however, had well-developed teeth in their jaws, as is well shown in (Fig. 47) which is a picture of a bird skeleton re- stored from bones found in the rocks of western Kansas. Near the base of the bill on either side, one can usually see an opening; these open- ings are the nostrils. On the sides of the head are the two eyes, and since they bulge out somewhat, the bird is afforded a wide range of vision. If the feathers below and behind the eye are pushed aside, an opening into the ear may be seen; this may be made out easily in the head of a chicken. 51. Wings. — In Figure 48 are shown the bones that com- pose the wing of an ostrich and the arm of a man, and on com- paring the two one sees a striking resemblance. In both, the upper arm has a single bone, while in the forearm there. Fig. 47. — Skeleton of a fossil bird. 'Beebe, "The 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 Peabody, James Edward, b. 1869; Hunt, Arthur Ellsworth, joint author. New York, The Macmillan company
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbiology, bookyear1912
