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Fishes and Birds

LINNÆUS distinguishes BIRDS into six orders, Accipitres, angular projecting beaks; Pica, compressed beaks, with climbing feet; Ansares, beaks with skin, and broad at end; Gralla, with three or four toes; Gallina, convex bill, and arched upper mandible; Paperes, conic, and pointed bills. In birds the vertebræ of the neck vary from 9 in the sparrow, to 23 in the swan. Of the back, from 6 in the bullfinch, to II in the swan and cassowary. Those in the tail, from o in the sparrow, to 9 in the ostrich. They have no lumber vertebræ. The pectoral muscle is fixed in birds, and they have three muscles to assist in flying, equal in bulk to all the other muscles. They have also peculiar muscles for perching. Birds exceed mammiferous quadrupeds in the quantity of their respiration, for they have not only a double circulation, and an ærial respiration, but they respire also through other cavities besides the lungs, the air penetrating through the whole body, and bathing the branches of the aorta or great artery of the body, as well as those of the pulmonary artery. The song of birds is a movement in succession, equal to a bar of 4 adagio crotchets, performed in 4 seconds. Of singing-birds, the nightingale unites the highest perfection of qualities, the linnet next, then the tit-lark, the sky-lark, and the wood-lark; the gold-finch and the robin excel in lively notes. Birds have two larynxes at each extremity of the windpipe. That next the lungs is the organ of singing. In some there are windings in the windpipe. The voluntary act of emptying the stomach is possessed by some birds, as the pigeon, which has an organ for secreting milk, and it softens the food for its young by previously swallowing it; and afterwards, putting its bill into theirs, returns it into their mouths.

Fishes. Air is as necessary to fishes as to animals, and they respire in sleep twenty-five times in a minute. The air is abstracted from the water by an apparatus called branchial, small, but extensive when spread out. They die in water deprived of its air under ice, or on having their gills tied up. The gills of fishes are composed of four plates on each side, and communicating with the throat by a single opening for each gill. They receive the water by these holes, and discharge cover.