SKELETON OF THE BIED. 



and humming-birds ; and in others flat, spoon-like, soft, and sensitive, as in the ducks 

 The movement of a bird's j-aw is not precisely similar to that of a mammal, owing to the 

 manner in which a certain little bone, termed from its squared shape the quadrate bone, 

 is articulated to the bones of the skull. On reference to the accompanying illustration, 

 this bone will be seen just at the junction of the lower jaw with the skull. 



Passing from the head to the neck, we find a marked distinction from the mammals. 

 In them, the vertebra of the neck are never more than seven in number ; the long neck 

 of the giraffe and the short one of the elephant being obtained by the prolongation of the 

 seven vertebroe in the former and their compression in the latter. In the birds, however, 

 there are never loss than nine vertebrae in the neck, and in some cases the number is 

 considerably greater ; the swan, for example, possessing no less than twenty-three of these 

 bones. The neck is also much longer in the birds, being in many instances longer than 

 the remainder of the body. The vertebrae of the neck are extremely flexible, as is needful 



for the peculiar habits of birds ; but those of the 

 back are immovably connected with each other, 

 and in many cases are even fused together. The 

 seven or eight short vertebroe which form the tail 

 are movable, and are generally terminated by a 

 single bone of greater length than any of the 

 others. 



We now proceed to the breast and body. The 

 ribs are chiefly remarkable for a flat appendage, 

 which starts from the lower portion of the bone, 

 and is directed backwards, so that it overlaps each 

 succeeding rib. The breast bone is placed lower 

 tliau might be supposed from the external aspect 

 of a bird, and is of very great size. Its substance 

 is much flattened, and it possesses a strong ridge 

 or keel of bone, which varies in its depth according 

 to the powers of flight possessed by the particular 

 species to which it belongs. As the eagle is a 

 strong-winged bird, the keel is very prominent, 

 but in such non-flying birds as the ostrich and 

 the apteryx, there is no keel at all. Between the 

 breast bone and the neck lie four clavicles, or 

 collar bones, differmg much in size and shape in 

 the various species of birds. One set of them, technically called the os fiirculare, from its 

 forked shape, is sometimes absent, its place being supplied by a ligament ; but the others, 

 termed the daviculce coracoidce, are invariably present. These two sets of bones are 

 familiar to all who have carved a fowl, imder the terms of "merry-thought" and 

 "neck bones." 



The limbs now come before our notice, and we cannot but be struck with the cvirious 

 fact, that in the birds the bipedal mode of walking again makes its appearance, having 

 disappeared through all the mammalia, with the exception of man. There is, however, 

 this analogy between the lower mammals and the birds, namely, that in both instances the 

 anterior limbs are intended for progression, although in the one case these formations belong 

 to earth, and in the other to the air. The bones of the wing present a considerable 

 resemblance to those of a man's arm, as may be seen by comparing the skeleton of the 

 eagle with that of the man in Volume I. The upper arm bone is of various lengths in the 

 different birds, being of wonderful proportions in such long-winged birds as the albatross, 

 but very short in the penguins, the cassowary, and many other birds. The two bones of 

 the fore-arm, technically called the ulna and radius, are also long in the long-winged 

 birds, and serve to carry a large expanse of feathers. Of these two, the ulna is the larger 

 and more cylindrical. To the end of the ulna and radius are jointed the two little boues 

 of tlie wrist, which bear a quasi hand, composed of a thumb and two fingers. The thumb 

 IS very small, consisting of either one or two bones ; and the fingers, which are only 



SKELETON OF EAGLE. 



