. Comparative zoology, structural and systematic. For use in schools and colleges. Zoology. HOW ANIMALS EAT. G9 jv correspond with the structure and habits of the animal, so that a single tooth is sufficent to indicate the mode of life and to identify the species.^' In the Ruminants, Ro- dents, Horses, and Elephants, the summits of the molars are flat, like mill-stones, with transverse or curving ridges of enamel. In the Cats and Dogs, they are narrow and sharp, passing by each other like the blades of scissors, and therefore cutting, rather than grinding, the food. The more purely carnivorous
. Comparative zoology, structural and systematic. For use in schools and colleges. Zoology. HOW ANIMALS EAT. G9 jv correspond with the structure and habits of the animal, so that a single tooth is sufficent to indicate the mode of life and to identify the species.^' In the Ruminants, Ro- dents, Horses, and Elephants, the summits of the molars are flat, like mill-stones, with transverse or curving ridges of enamel. In the Cats and Dogs, they are narrow and sharp, passing by each other like the blades of scissors, and therefore cutting, rather than grinding, the food. The more purely carnivorous the species, and the more it feeds upon living prey, the fewer the molars. In ani- mals living on mixed diet, as the Hog and Man, the crowns have blunt tubercles. Premolars, or bicuspids, are those which were preceded by milk-teeth; the true, or back, molars had no predecessors. The dentition of Mammals is expressed by a formula, which is a combination of initial letters and figures in. Fig. 33.—Teetli of the right lower jaw of adult male Chimpanzee {Troglodytes niger), natural size. Tlie molar series does uot form a cuive, as iu Mau. fractional form, to show the number and kind of teeth on each side of both jaws. Thus, the formula for Man is:i,|5|; o,Jfi;i>,H; m, t| = 32. The teeth of Mammals are always restricted to the mar- gins of the jaws, and form a single row in each. But they never form an unbroken series in any living species, ex-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Orton, James, 1830-1877. New York, Harper and brothers
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