The =inferior= or =alveolar border= (Processus alveolaris) is thick, and presents six large cavities, the =alveoli=, for the cheek teeth. The alveoli are separated by transverse =interalveolar septa=. There is often a small alveolus for the first premolar (“wolf tooth”) close to the first large one. Further forward the border is narrow and forms part of the =interdental= or =interalveolar space= (Margo interalveolaris). Behind the last alveolus is a rough area, the =alveolar tuberosity=. The =anterior extremity= is pointed. It joins the premaxilla, and forms with it the alveolus for the canine tooth. The =posterior extremity= forms a rounded prominence, the =maxillary tuberosity= (Tuber maxillare). Internal to the tuberosity is a deep cavity, the maxillary hiatus, in which are three foramina. The upper one, the =maxillary foramen=, leads into the infraorbital canal. The lower one, the =posterior palatine foramen=, is the entrance to the palatine canal. The =sphenopalatine foramen= perforates the inner wall of the hiatus and opens into the nasal cavity. The =zygomatic= or =temporal process= (Processus temporalis) projects backward above and external to the tuberosity; it is overlapped by the corresponding part of the malar and also articulates with the zygomatic process of the temporal. A small curved plate extends inward from it and joins the frontal and palate bones, forming part of the floor of the orbit. The =palatine process= (Processus palatinus) is a plate which projects horizontally inward from the lower part of the inner surface of the body. It forms the greater part of the basis of the hard palate. Its =superior= or =nasal surface= is smooth and concave transversely; on its anterior part, close to the inner border, is a shallow groove in which the organ of Jacobson is situated. The inferior or =palatine surface= is slightly concave from side to side, and presents along its outer part the =palatine groove= (Sulcus palatinus). The groove is a continuation of the palatine canal, and contains the palatine artery and nerve. The =internal border= unites with its fellow to form the median palatine suture; its nasal aspect bears the nasal crest, which forms, with that of the opposite process, a groove for the vomer. The =posterior border= unites with the horizontal part of the palate bone at the transverse palatine suture. [Illustration: FIG. 31.—UPPER JAW OF HORSE ABOUT FOUR AND A HALF YEARS OLD, VENTRAL VIEW. 1, 1, Posterior nares; 2, vomer; 3, horizontal part of palate bone; 4, anterior palatine foramen; 5, palatine groove; 6, transverse palatine suture; 7, median palatine suture; 8, palate process of maxilla; 9, palate process of premaxilla; 10, foramen incisivum; 11, malar bone; 12, maxilla; 13, anterior end of facial crest; 14, interalveolar space; I. 1–3, incisor teeth; _C_, canine tooth; _P1_, first premolar or “wolf” tooth. ]