The =palatine region= comprises a little more than half of the entire length of the base of the skull (Fig. 31). The =hard palate= (Palatum durum) is concave from side to side, and in its length also in the anterior part. It is formed by the palatine processes of the premaxillæ and maxillæ, and the horizontal parts of the palate bones. It is circumscribed in front and laterally by the =superior alveolar arch=, in which the upper teeth are implanted. The =interalveolar space= (Margo interalveolaris) is that part of the arch in which alveoli are not present. Behind the last alveolus is the =alveolar tuberosity=, and internal to this is a =groove= for the palatine vein. In the middle line is the =median palatine suture= (Sutura palatina mediana). In the line of the suture, a little behind the central incisors, is the =foramen incisivum=, through which the palato-labial artery passes. On either side, parallel with the alveolar part of the maxilla, is the =palatine groove= (Sulcus palatinus), which contains the palatine vessels and nerve. It is continuous at the anterior palatine foramen with the palatine canal, which is situated between the maxilla and the palate bone. The =palatine cleft= (Fissura palatina) is the narrow interval along the outer margin of the palatine process of the premaxilla; it is closed in the fresh state by cartilage. Scattered along each side of the palate are several vascular foramina. The =transverse palatine suture= (Sutura palatina transversa) is about half an inch from the posterior border. The latter is in a plane through the last molar teeth, and is concave and free. [Illustration: FIG. 34.—CRANIAL CAVITY OF HORSE AS SEEN ON SAGITTAL SECTION OF SKULL. _O_, Frontal sinus; _r_, sphenoidal sinus; _t_, cerebral compartment of cranium; 1–3, ridges (juga) corresponding to fissures of lateral surface of cerebrum; 4, groove for middle cerebral artery; 5, entrance to for. lacerum orbitale; 6, entrance to optic foramen; 7, 8, grooves on sphenoid bone; 9, incisura spinosa; 9′, groove for middle meningeal artery; 10, fossa for pyriform lobe of cerebrum; 11, incisura ovalis; 12, incisura carotica; 13, internal auditory meatus; 14, foramen lacerum basis cranii; 15, hypoglossal foramen; 16, petrous temporal; 17, orifice of aquæductus vestibuli; 18, orifice of aquæductus cochleæ; 19, foramen magnum; 20, petrosal crest; 21, two plates of frontal bone; 22, supraoccipital; 23, basioccipital; 24, tentorium osseum; 25, body of sphenoid. (After Ellenberger-Baum, Top. Anat. d. Pferdes.) ]