. The comparative anatomy of the domesticated animals. Veterinary anatomy. 422 THE DIGESTIVE APPARATUS IN MAMMALIA. tooth which has been worn, an external covering of enamel, and two circles, or rather two irregular polygons, of central enamel circumscribing the two cavities. In the superior molars, these bands of enamel represent a Gothic B, having a small appendage on the loop nearest the entrance to the mouth. This hgure is modified in the teeth of the lower jaw, the enamel of the infundibuli being con- tinuous, on the inner side, with the external enamel. The cement is extremely- abundant,
. The comparative anatomy of the domesticated animals. Veterinary anatomy. 422 THE DIGESTIVE APPARATUS IN MAMMALIA. tooth which has been worn, an external covering of enamel, and two circles, or rather two irregular polygons, of central enamel circumscribing the two cavities. In the superior molars, these bands of enamel represent a Gothic B, having a small appendage on the loop nearest the entrance to the mouth. This hgure is modified in the teeth of the lower jaw, the enamel of the infundibuli being con- tinuous, on the inner side, with the external enamel. The cement is extremely- abundant, and in the upper molars its total quantity nearly equals that of the dentine ; it accumulates in the cuh-de-sac and on the external covering of enamel, where it partially fills up the flutings on the faces of the crown. Prolonged steeping of a molar tooth in hydrochloric acid, easily permits the isolation of these elements. Owing to the arrangement above described, the section of an adult molar tooth, naturally represented by the surface of friction (Fig. 234), exhibits, out- wardly, a layer of cement; next, the external enamel; between this and the central enamel, the dentine, always yellower, and sometimes even black in the middle ; lastly, the enamel bands of the infundibuli, and the crusta petrosa filling them. As these enamel bands are much harder than the other substances, they are worn more slowly, and stand out in relief on them. The table of the tooth has also, for this reason, the appearance of a veritable mill-stone, and is admirably disposed for the trituration of those fibrous substances on which the animal usually feeds. The follicle which develops these three elements of _ i> ** the molar tooth, has at the bottom an enormous papilla TRANSvKRsii SECTION OF A divided iuto SBVcral lobes, which lie too-ether for their horse's upper molar ,11 ^, 1 J J • xi • X 1 J X 1 TOOTH. whole length ; lodged m the mternal dental cavity, it A, External cement; B, ex- gradu
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