SEC. in EXTERIOR PARTS OF BIRDS 13^ 



swimming birds. But many swimmers, as swans and cormorants, 

 have extremely long necks ; and some waders, as plovers, have 

 very short ones. A long neck is a rarity among the higher birds 

 (above the GalUnce), in most of which the head seems to nestle upon 

 the shoulders. The longer the neck, the more sinuous and flexible 

 is it likely to be. Anatomically, the neck ends in front at the 

 articulation of the atlas (first cervical vertebra) with the skull, and 

 behind at the first vertebra which bears free jointed ribs reaching 

 the sternum. (See also § 4, Anatomy.) The shape of the 



Body proper, or Trunk, is obviously referable to that of the 

 egg ; it is ovate (Lat. ovum, an egg ; whence oval, the plane figure 

 represented by the middle lengthwise section of an egg ; ovate or 

 . ovoid, the solid figure). The swelling of the breast represents the 

 greatest diameter of the egg, usually near the larger end. But the 

 ovoid is never perfectly expressed, and departures from the figure 

 are numberless. In general, the higher perching birds have the 

 body nearly of the ovate shape ; among waders, the figure is usually 

 compressed, or flattened vertically, as is well seen in the herons, and 

 still better in the rails, where the lateral narrowing is at an extreme ; 

 among swimmers, the body is always more or less depressed, or 

 flattened horizontally, and especially underneath, that the birds 

 may rest on the water with more stability, as well shown by a duck 

 or diver. Anatomically the body begins with the foremost dorsal 

 or thoracic vertehrce, or those that bear true ribs ; laterally, it ceases 

 quite definitely at the shoulder-joints, the whole of the fore limb 

 being outside the general content of the trunk; behind, in the 

 middle line, it includes everything, only the t&il-feathers themselves 

 being beyond it ; behind and laterally, it includes more or less of 

 the legs, for these are generally buried in the common integument 

 of the body to the knee-joint, nearly or quite so, and sometimes to 

 the heel-joint ; though in anatomical strictness the trunk should be 

 limited by the hip-joint. The rib-bearing part of the back-bone, 

 the ribs themselves, and the greatly enlarged breast-bone (Lat. 

 sternum) compose the walls of the chest (Lat. thorax). Upon this 

 bony box, which contains the heart and lungs and some other 

 viscera, are saddled on each side the bones of the shoulder-girdle or 

 scapular arch, namely, the shoulder-blades (Lat. scapulce), the coracoids, 

 and the collar-bones (Lat. claviculce), all three of which, on each side, 

 come together at the shoulder-joint (Figs. 1, 2). The thoracic cavity is 

 not separated by any partition or diaphragm from that of the belly 

 (Lat. abdomen), which with the pelvis, or basin, contains the digestive, 

 urinary, and genital organs. The pelvis is composed, in dorsal 

 mid-line, of so many of the vertebrse (dorso-lumbar, sacral proper, and 

 urosacral), as become immovably joined to one another, and later- 

 ally of the confluent haunch - bones. The numerous anchylosed 



