EXTEBNAL FARTS OF BIRDS. — TOFOGBAPHY. 93 



turn) enveloped in muscle, along which in front lie the gullet (Lat. amophagus) and windpipe 

 (Lat. trachea), with associate blood-vessels, nerves, etc. Its length is very varialilo, as is the 

 number of its bones, the latter ranging from 8 to about 26. Bearing as it does the head, witli 

 the hill, which is the true hand of a bird, the neck is extremely flexible, to permit th(; neces- 

 sarily varied movements of this liaudy member. Its least length may be said to be tliat which 

 allows the point of a bird's beak to reach the (jil-gland on the rump ; its greatest length some- 

 times exceeds that of the body and taU together, as in the case of a swan, crane, or heron. The 

 length is usually in direct proportion to that of the legs, in obvious design of allowing the beak 

 to touch the ground easily to pick up food. The neck is habitually carried iu a double curve, 

 like an open S or italic /, the lo^-er belly of tlie curve, convex forward, fitting in between the 

 forks of the merry-thiiught (Lat. furculiim), the upper curve holding the head horizontal at the 

 same time. This " sigmoid flexure" (sigma, Greek S), highly characteristic of the bird's neck, 

 is produced by the saddle-shaping of the articular surfaces of the several bones. The mechan- 

 ical arrangement is such, that the sigma may be easily bent till the upper end (headj rests (ju 

 the lower convexity, or as easUy straightened to a right line ; but little if any further deviation 

 in opposite curvature is permitted. As a generalization, the neck may be called relatively 

 longest in wading birds, as herons, cranes, ibises, etc. ; shortest in perching birds, as the great 

 majority of small Insessores ; intermediate in swimming birds. But many swimmers, as 

 swans and cormorants, have extremely lung 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 before at the articulation of the 

 atlas (first cer^'ical vertebra) with the skuU, and behind at the first vertebra wliich bears fi-ee 

 jointed ribs reacMng the sternum. (See also p. 133, 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 arc numberless. In general, the higher perching birds have the 

 liody 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 narrow- 

 ing 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 vertebrte, 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, (uily the tuil-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 liody to the knee-joint, nearly or quite so, and sometimes to the 

 heel-joint ; thfiugh more strictly 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 cavity of the chest (Lat. thorax). Upon tliis bony l)0x, which contains the 

 heart and lungs and some other viscera, are saddled on each side the bones of the shotdder-girdle 

 (jr scapular-arcli, namely, the shoulder-blades (Lat. scapiida) ,t\ie coracoids, and the collar-bones 

 (Lat. clavicula), all three of which come together at the shoulder-joint. The thoracic cavity 

 is not separated by any partition or diaphragm from that of the belly (Lat. cthdomen), wldch 

 ivith the pelvis, or basin, contains the digestive, urinary, and genital organs. The pelvis is 

 composed, in dorsal mid-line, of so many of the veilebrie {dorso-liimhar, sacral proper, and 

 urosacral, as become immovably joined to one another, and laterally of the confluent haunch- 



