File:Comparative zoology, structural and systematic - for use in schools and colleges (1883) (20661542372).jpg

Title: Comparative zoology, structural and systematic : for use in schools and colleges
Identifier: comparativezool00orto (find matches)
Year: 1883 (1880s)
Authors: Orton, James, 1830-1877; Birge, E. A. (Edward Asahel), 1851-1950
Subjects: Zoology; Anatomy, Comparative; Physiology, Comparative
Publisher: New York : Harper & Bros.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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Text Appearing Before Image:
HOW ANIMALS EAT. 67
Text Appearing After Image:
Fig. 32.—Jaws and Pavement-teeth of a Ray (Myliohates). fish (Myxine) has a single tooth on the roof of the mouth, and two serrated plates on the tongue; while the mouth of the Pike is crowded with teeth. In some we find teeth short and blunt, in the shape of cubes, or prisms, arranged like mosaic work. Such pavement-teeth (seen in some Rays) are fitted for grinding sea-weed and crush- ing shell-fish. But the cone is the most common form: sometimes so slender and close as to resemble plush, as in the Perch; or of large size, and flattened like a spear - head writh serrated edges, as in the Shark; but more often like the canines of Mammals, curved inward to fit them for grappling. In the Shark, the teeth are confined to the fore-part of the mouth; in the Carp, they are all situated on the bones of the throat; in the Parrot-fish, they occupy both back and front; but in most Fishes the teeth are developed also on the roof, or palate, and, in fact, on nearly every bone in the mouth. They seldom appear (as in the Salmon) on the upper max- illary. As to mode of attachment, the teeth are generally anchylosed (fastened by bony matter) to the bones which support them, or simply bound by ligaments, as in the Shark. In a few Fishes, the teeth consist of flexible car- tilage ; but almost invariably they are composed of some kind of dentine, enamel and cement being absent. Of Amphibians and Reptiles, Toads, Turtles, and Tor- toises are toothless; Frogs have teeth in the upper jaw only; Snakes have a more complete set, but Saurians pos- sess the most perfect dentition. The number is not fixed even in the same species: in the Alligator it varies from 72 to 88. The teeth are limited to the jawbones in the higher forms (Saurians); but in others, as the Serpents,

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