AYES, birds, the name of the second class of animals, according to the Linnman system. They have been described as animals, having a body covered with fea thers and down ; jaws protracted and naked ; two wings, formed for flight; and two feet. They are aerial, vocal, swift, and light, and destitute of external ears, lips, teeth, scrotum, womb, bladder, epi glottis, corpus callosum and its arch, and diaphragm. The feathers are disposed over each other in the form of a quincunx, intermixed with down, distinct from the quill and tail feathers, convex above, con cave beneath, narrower on the outside, lax at the fore-end, hollow and horny at the base, with a central pith, and furnish ed on each side the elongated shaft with parallel, approximate, distinct, and flat lamina, composing the vane ; they vary in colour, according to age, sex, season, or climate, except the quill and tail lea thers, which are more constant, and chief. ly characteristic. The eggs are various in number, size, and colour, but always covered with calcareous shell, deposited in an artificial nest, and hatched by the genial warmth of the parent. The body is oval, terminated by a heart•shaped rump, and furnished all over with aerial receptacle s,communicati ng with the lungs or throat, necessary for flight song, and which may be filled or emptied at pleasure ; the rump has two glands, se creting an unctuous fluid, which is press ed out by the bill, to anoint the discom posed parts of the feathers ; the bill is horny, extending from the head, either hooked at the end for tearing the prey, or slender for searching in the mire, or flat and broad for gobbling; and is used for building nests, feeding the young, climbing, or as an instrument of offence and defence ; eyes lateral, furnished with orbits, and nictitant membrane; ears trun cate, without auricles; wings compressed, consisting of moveable joints, and cover ed with quills and feathers; legs placed usually near the centre of gravity, with toes and claws of various shapes : tail serving as the rudder or director of the body ; they are mostly monogamous, or live in single pairs, and migrate into mild er climates, upon defect of food 01? warmth, and a few become torpid in win ter. The generic characters are taken
from the bill, tongue, nostrils, eerie, carun des, and other naked parts. See Plate I. Ayes Fig. 1. a. Spurious or bastard wings: b. lesser coverts of the wings, which are small feathers that lie in several rows on the bones of the wings ; c. greater wing coverts or feathers, that lie immediately over the quill feathers; d. scapulars, which take their rise from the shoulders, and cover the sides of the back ; e. • pri mary quill-feathers, that rise from the first bone ; f secondary quill-feathers, or those that rise from the second bone ; g. tertials, which likewise take their rise from the second bone, forming a con tinuation of the secondaries, and seem to do the same with the scapulars that lie over them ; these feathers are so long in some of the scolopax and tringa genera, that, when the bird is flying, they give it the appearance of having four wings ; h. rump ; i. tail-coverts, k. tail-feathers ; 1. shoulders; el. crown ; n. front ; o. hind. head; p. nape: g. chin ; r. throat ; a. scrag or neck above ; t. interscapular re gion; u. vent.
Fig. 2. a. Upper-mandible ; b. lower mandible ; c. a tooth-like process ; d. frontlet; e. front; f. crown ; g. hind head ; h. nape ; i. lores ; k. temples ; 1. cheeks ; m. chin ; st. bristles at the base of the bill.
s Fig. 3. a. A bill with the tipper man dible hooked at the point, and furnished with a tooth-like process ; S. the sere or naked skin which covers the base of the bill, and in which are placed the nostrils ; c. orbits, or skin, which surrounds the eye : it is generally bare, but particularly in the parrot and heron.
Fig. 4. A flat bill, pectinate at the edges, and furnished at the tip with a claw or nail.