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Show 222 AVES. h Phagus • a membranous stomach, in the thickness of t e eso ' h . . h whose parietes are a multitude of glands w os~ JUICes umect th liment • and :finally, the gizzard, armed With two power· fi 1e ma uscles ' united by two radiated tendons, an d 1m" ed m. ter. n~lly with~ cartilaginous kind ~f velvet. The food is the more easily ground there, as birds constantly swallow small stones in order to increase its triturative power. In ~he greater part of the species which feed exclusively on flesh or fish the muscles and villous coat of the gizzard are greatly atte' nuated; and it seems to make but a sm. g l e sac with the membranous stomach. The dilatation of the crop is also sometimes wanting. The liver pours its bile into the intestine by tw~ ducts, which alternate with the two or three through wh1ch the pancreatic fluid passes. The panc~eas of ~irds. is large,_ but their spleen is small ; the epiploon IS w~~tmg; Its fu~ct1on~, however, are partly fulfilled by the partitions of th~ ~1r caVl· ties; two blind appendages are situated near the origm of the rectum, and at a short distance from the anus; they are longer or shorter, according to the regimen of the genus. In the Herons it is short; in other genera, that of the Woodpeckers for instance, it is totally deficient. The cloaca is a pouch, in which the rectum, ureters, spe~· matic ducts, and in the female, the oviduct, terminate; It opens externally, by the anus. Strictly spea~ing, ~irds do not urinate as that excretion mingles with the1r sohd excre· ment. In' the Ostriches alone, is the cloaca sufficiently dilated to allow of an accumulation of the urine. In most genera, coition is effected by the simple juxt~· position of the anus; the Ostriches, and several of the Palmi· pedes, however, have a penis furrowed with a groove, through which the semen passes. The testes are situated· internally, and near the lungs ; only one oviduct is developed; the other is reduced to a small sac. The egg, detached from the ovary, where it consists mere 1Y of yolk, imbibes that external fluid, called the w?ite! in t~I~ upper part of the oviduct, and becomes invested With 1ts ~~at the bottom of the same canal. The chick contained Wit 1n AVES. 223 it is developed by incubation, unless the heat of the climate suffices for that purpose, as is the case with the egg of the Ostrich. The young Bird has a little horny point at the extremity of the beak, with which it splits open the shell, and which fails off a few days after it is hatched. The industry and skill ~xhibited by Birds in their variously con~tructed nests, and their tenderness and care in protecting ~eir eggs and y~u~g, ~re known ~o every one; it is the princ~ pal part of_ their mstm~t. Their rapid transitions through different regwns of the a1r, and the vivid and continual action of t~at element upon them, enable them to anticipate atmospheriC changes, to an extent of which we can form no idea and caused the ancients, in their superstition, to attribute t~ t~em the po';er of prescience or divination. It is unquestionably on this faculty, that depends the instinct which acts upon the Birds of passage, prompting them to seek the south on the approach of winter, and the north on the return of spring. They have memory, and even imagination-for they dre~m. T~ey are easily tamed, may be taught to render vanous serviCes, and retain the air and words of songs. Division of the Class of Birds into Orders. Of all classes of animals, that of Birds is the most strongly characterized, that in which the species have the greatest mutual resemblance, and which is separated from all others _by the greatest interval ; circumstances which, at the same time, render its subdivision the more difficult. Their distribution is founded, like that of the Mammalia on the o. r gans of manducation or the beak, and on those of p' re-hension, that is, on the beak, and particularly on the feet. The first that arrest our attention are the palrnated ~'eet or those · h" h J c ' . . m. w Ic the toes are connected by membranes, which dist~ngmsh all Swimming Birds. The position of these feet b~hmd ; the length of the sternum; the neck, often longer t an the legs to enable it to reach below; the dense, polished |