A pike has been known to live in a pond 90 years; and Gesner relates that in 1497 an enormous pike was caught in a lake near Heilbronn, in Swabia, with a brass ring attached to it, recording that it was put into the lake in 1230. The pike must have lived, therefore, at least 2G7 years. The ring is still preserved at Mannheim. The age of the whale is known by the size and number of lamina) of certain organs in the mouth, formed of a horny substance, commonly called whalebone. These laminae increase yearly, and if the mode of computation be correct, they indicate in certain cases that the animal attains to an age of 400 years. Little is known of the age attained by animals of the lower types, such as articulata, mollusca, and radiata. That of insects has received some attention, and it has been remarked that though the first period of life, passed in the grub or caterpillar state, extends to several months or even years, the great majority live but a few days or weeks after the metamorphosis by which they attain to a more perfect form.

The ephemera, when it leaves its grub-life in the water, and assumes a higher form and an aerial existence, lives but a few hours, and dies the very day on which it was born into its new life; whence its name, ephemera, passing in a day. - The age of the horse in his ascending phase of life is known chiefly by the growth and appearance of the teeth, and more especially of the incisors, commonly called nippers. In each jaw of the horse there are six of these nippers, broad, thin, and trenchant in the foal; while in the adult animal the crowns become flat, and marked in the centre with a hollow disk. The foal or milk teeth appear about 15 days after birth. At 2 1/2 years of age the middle pair drop, and are replaced by the corresponding pair of permanent teeth. At 3 1/2 years the two next, one on each side, are likewise replaced. At 4 1/2 years the two external nippers or excisors drop and make room for the corresponding pair of permanent teeth. All these permanent nippers are flattened on the crown or upper surface, and marked in the centre with a circular hollow pit; this pit is gradually effaced, as the tooth wears slowly down to a level with the bottom.

By the degree of this detrition, or wearing of the teeth, the age of the animal is determined up to the 8th year, when the marks are generally quite effaced. The external pair of nippers, however, appearing a year or two after the intermediate pair, preserve their original form proportionately later. The age of a horse may still be determined for a few years, after the 8th year, by the appearance and comparative length, of the canine teeth, or tushes; these, however, are sometimes wanting, particularly in the lower jaw, and in mares they are rarely developed at all. The tushes of the under jaw appear at the age of 3 1/2 years, those of the upper jaw at 4. They are sharp-pointed until the age of 6, and at 10 become blunt and long, because the gums begin about that time to recede from the roots of the teeth, leaving them naked and exposed. After this period there are no certain means of determining the age of a horse, but some conjecture may be made from the comparative size, bluntness, and discolored appearance of the tushes. - The age of horned cattle is more readily determined by the growth of the horns than by the growth, succession, and detrition of the teeth.

But the horns of oxen, sheep, goats, and antelopes, being hollow and permanent, differ widely in form, structure, and manner of growth from those of the deer tribe. The deer kind shed their horns annually, and, with the single exception of the reindeer, the males alone have horns. At first they have them in the form of simple prickets, without any branches or antlers; but each succeeding year adds one or more branches, according to the species, up to a certain fixed period, beyond which the age of the animal can only be conjectured from the size of the i horns and the thickness of the burr or knob at ! their roots, which burr connects them with the skull. The prickets or first horns of the common stag fall during the 2d year of the animal's life, each one being replaced by one with a single antler, and thence called the fork. This falls during the 3d year, and is replaced by the | 3d kind, which has commonly 3 or 4, and sometimes 5 branches. The 4th and following pair have a like number of branches, and the number of antlers goes on increasing in the same manner till the 8th year of the animal's life; after which they follow no fixed rule, but continue to increase in number, particularly near the summit of the horn, where they are sometimes grouped in the form of a coronet, and thence called "royal antlers." The fallow deer, the roebuck, and other species of this genus, present similar examples of development; the number of the antlers increasing in a fixed ratio up to a certain time, beyond which the age, as in the stag, can only be determined by the comparative size of the burr and that part of the shaft or horn from which the antlers grow.

In the fallow deer, the prickets of the 2d year are replaced by horns bearing two antlers already indicating the palmated form which afterward distinguishes them from the antlers of other deer. This palm increases in breadth, and assumes an indented form on the superior and posterior borders, and the 4th pair of horns, shed in the 5th year of the animal's life, are replaced by others in which the palm is cloven or subdivided irregularly into distinct parts, assuming in old animals a great diversity and singularity of form. Finally, the horns begin to shrink in size, and are said to end in becoming simple prickets as in the 1st year. The horns of oxen, sheep, goats, and antelopes are hollow and permanent. They consist of a sheath of horn covering a bony core or process of the skull, and growing from the root, where an additional knob or ring is formed each year; and thus the number of these rings is a sure indication of the animal's age. The growth of the horns is not uniform throughout the year, but varies with the seasons. The increase takes place in the spring, and there is no further addition until the following year.