. Comparative dental anatomy. Teeth; Dentistry. 120 COMPAEATIVE DENTAL ANATOMY horny structures which take the place of teeth. The Ornithorynchus is a mammal living in Aus- tralia with a bill like a duck, and like the duck's bill transversely ridged to strain food from the water. Each jaw is provided with four horny teeth, of which the two front ones have long ridges and the back ones are tubercular and cal- careous, somewhat like true grinding teeth. Their structure is a fibrous, horny substance, like hoofs or nails, with only three per cent, of earthy matter. The other member of the order, t
. Comparative dental anatomy. Teeth; Dentistry. 120 COMPAEATIVE DENTAL ANATOMY horny structures which take the place of teeth. The Ornithorynchus is a mammal living in Aus- tralia with a bill like a duck, and like the duck's bill transversely ridged to strain food from the water. Each jaw is provided with four horny teeth, of which the two front ones have long ridges and the back ones are tubercular and cal- careous, somewhat like true grinding teeth. Their structure is a fibrous, horny substance, like hoofs or nails, with only three per cent, of earthy matter. The other member of the order, the. FlG. 38.—-Duck-billed Platypus (Ornithorynchus anatinus). Echidna, has an edentulous bill, but has the tongue and roof of the mouth covered with horny spines to crush the ants caught by its viscous tongue. The next highest order of mammals is that of the Bruta, which comprises the Sloths, Armadil- los, Ant-eaters, etc., which are of very low or- ganization. They were first called Edentata,— without teeth,—and later were described as be- ing without incisor teeth, as median incisors are absent in all the members of the order. The teeth are also destitute of enamel, the dentin alone. 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 Thompson, Alton Howard, 1849-1914; Dewey, Martin, 1881-. St. Louis, C. V. Mosby
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