. Animate creation : popular edition of "Our living world" : a natural history. Zoology; Zoology. RODENTIA; OR GNAWING ANIMALS. HE Rodents, or gnawing animals, derive their name from the peculiar structure of their teeth, which are specially fitted for gnawing their way through hard sub- stances. The jaws of the Rodents are heavily made, and very large in propor- tion to the head, their size being not only needful for the support of the gnawing teeth, but for their continual development. There are no canines, but a wide gap exists between the incisors and the molars, which are nearly
. Animate creation : popular edition of "Our living world" : a natural history. Zoology; Zoology. RODENTIA; OR GNAWING ANIMALS. HE Rodents, or gnawing animals, derive their name from the peculiar structure of their teeth, which are specially fitted for gnawing their way through hard sub- stances. The jaws of the Rodents are heavily made, and very large in propor- tion to the head, their size being not only needful for the support of the gnawing teeth, but for their continual development. There are no canines, but a wide gap exists between the incisors and the molars, which are nearly tiat on their surfaces, and are well suited for grinding the soft substances on which these animals feed. The structure of the chisel-edged incisor teeth is very wonderful, and may be easily under- stood by inspecting the teeth of a rat, mouse, hare, or rabbit. As their teeth are continually worn out by the severe friction which they undergo, there must needs be some provision for renewing their substance, or the creature woidd soon die of starvation. In order to obviate this calamity, the base of the incisor teeth pass deeply into the jaw-bone, where they are continually nourished by a kind of pulpy substance from which the tooth is formed, and which adds fresh material in proportion to the daily waste. Some- times it happens that one of the incisor teeth is broken or injured by some accident, so that it offers no resistance to its corresponding tooth in the opposite jaw. The result of such an accident is very sad to the sufferer, and is not unfrequently fatal in its termination. For the unopposed tooth, being continually increased by fresh substance from behind, is gradually pushed forward until it attains an enormous length, having sometimes been known to form a complete circle. Examples of these malformed teeth are of tolerably frequent occurrence, and specimens may be seen in almost every museum of comparative anatomy. Something more is needed for the well-being of the an
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Keywords: ., bookauthorbr, bookcentury1800, bookdecade1890, booksubjectzoology
