The =interparietal bone= fuses with the occipital before birth. It forms the high posterior part of the sagittal crest, and is wedged in between the two parietal bones. The tentorium osseum is thin and curved, concave ventrally. Its base concurs with the occipital and parietal bones in the formation of a transverse canal which is continuous with the parieto-temporal canals. [Illustration: FIG. 123.—SKULL OF DOG, DORSAL VIEW. _I_, Occipital; _II_, parietal; _III_, frontal; _IV_, lacrimal; _V_, malar; _VI_, squamous temporal; _VII_, nasal; _VIII_, maxilla; _IX_, premaxilla; _1_, supraoccipital; _2_, interparietal; _3_, parieto-occipital suture; _4_, occipital crest; _5_, sagittal crest; _6_, parieto-frontal suture; _7_, squamous suture; _8_, parietal eminence; _9_, antero-external angle of parietal bone; _10_, frontal crest; _11_, _14_, orbital margin; _12_, supraorbital process; _13_, frontal fossa; _15_, temporal part of frontal bone; _16_, nasal process of frontal bone; _17_, frontal suture; _18_, lacrimal foramen; _19_, maxillary process of frontal bone; _20_, lacrimo-maxillary suture; _21_, frontal process of malar bone; _22_, lacrimal process of malar; _23_, zygomatic process of malar; _24_, zygomatic process of squamous temporal; _24′_, posterior end of nasal bone; _25_, nasal suture; _26_, anterior end of nasal bone; _27_, infraorbital foramen; _28_, canine tooth; _29_, cheek tooth; _30_, frontal process of maxilla; _31_, body, _32_, nasal process, _33_, palatine process of premaxilla; _34_, palatine fissure; _35_, incisor teeth. (Ellenberger-Baum, Anat. d. Hundes.) ] The =parietal bone= is rhomboid in outline and is strongly curved. It is extensive and forms the greater part of the roof of the cranial cavity. At the junction of the right and left bones there is a prominent sagittal crest which is continued upon the frontal bones. The lower border articulates with the temporal wing of the sphenoid by its anterior part and with the squamous temporal in the remainder of its extent. The external surface enters into the formation of the temporal fossa. The internal surface is marked by digital impressions, and by grooves for the middle meningeal artery and its branches. The external surface of the =frontal bone= is crossed by a frontal crest, which extends in a curve from the sagittal crest to the supraorbital process, and separates the frontal and temporal parts. The frontal parts of the two bones form a central depression and slope downward and forward. The supraorbital process is very short, so that the orbital margin is incomplete as in the pig. The supraorbital foramen is absent. In front there is a narrow pointed nasal part which fits in between the nasal bone and the maxilla. The orbital and temporal parts are relatively extensive. Two ethmoidal foramina are commonly present. The frontal sinus is confined to the frontal bone.