575. Standing next to the lateral incisor is the cuspid, canine, or eye-tooth (figs. CLV., CLVI., and CLVII.). It is the longest of all the teeth. Its office is to tear such parts of the food as are too hard to be readily divided by the incisors. 576. Next the cuspid are the bicuspid, two on each side (fig. CLV., CLVII.), so named from their being provided with two distinct prominences or points. Their office is to tear tough substances preparatory to their trituration by the next set. [Illustration: Fig. CLVI. Front or external view of the upper teeth. 1. The central incisor. 2. The lateral incisor. 3. The cuspid. 4. The first bicuspid. 5. The second bicuspid. 6. The first molar. 7. The second molar. 8. The third molar, or dens sapientiæ.] 577. The molars, or the grinders, three on each side (fig. CLVI. and CLVII.), provided with four or five prominences on the grinding surface, with corresponding depressions, which are so arranged that the elevations of those of the upper are adapted to the concavities of those of the lower jaw, and the contrary. [Illustration: Fig. CLVII. Front view of the lower teeth. 1. The central incisor. 2. The lateral incisor. 3. The cuspid. 4. The first bicuspid. 5. The second bicuspid. 6. The first molar. 7. The second molar. 8. The third molar, or dens sapientiæ.] 578. From the incisor to the molar teeth there is a regular gradation in size, form, and use, the cuspid holding a middle place between the incisor and the bicuspid, and the bicuspid being in every respect intermediate between the cuspid and the molar. Thus the incisor are adapted only for cutting, the cuspid for tearing, the bicuspid partly for tearing and partly for grinding, and the molar solely for grinding. The incisor has only a single root, which is nearly round, and quite simple (fig. CLVII. 1, 2); the cuspid has only a single root, but this is flattened and partially grooved (fig. CLVII. 3); even the bicuspid has only a single root, but this is commonly divided at its extremity, and is always so much grooved as to have the appearance of two fangs partially united, the body having two points instead of one, thus approaching it to the form of the molar (fig. CLVII. 4, 5); and these last have always two, sometimes three, occasionally four roots, and their body is greatly increased in size, and has a complete grinding surface (fig. CLVII. 6, 7, 8).