THE SKULL AS A WHOLE 173 



Above this prominence is a pair of foramina. The alveolar border presents six 

 alveoli for the incisor teeth, and a little further back two large cavities for the 

 canine teeth. There are two pairs of mental foramina of considerable size and a 

 variable number of smaller ones. The rami cUverge more than in the horse or ox, 

 and the upper part is somewhat incurved. The horizontal part is very thick and 

 strong. Its lateral surface is stronglj^ convex from above downwai'd. The medial 

 surface is prominent over the roots of the molar teeth and overhangs the concave 

 lower part. The alveolar border is thin in front and widens behind; it does not 

 follow the axis of the ramus, but runs nearly straight and produces the marked over- 

 hang noted above. There are seven alveoli for the lower cheek teeth, which in- 

 crease in size from before backward. The first is small, not alwa>'s present in the 

 adult, and is separated by short spaces from the second and the canine alveolus. 

 The vertical part is relatively wide above. The condyle is convex in both direc- 

 tions, wide in front, narrow and declivitous behind. The very small and thin- 

 edged coronoid process is not quite so high as the condyle, from which it is separated 

 by a very wide notch. The mandibular foramen is large. The two halves of the 

 bone unite soon after birth in the improved breeds. 



The body of the hyoid bone is broad from before backward, short transversel}', 

 and bears on its ventral aspect a very short pointed lingual process. The thyroid 

 cornua are wide and curved, concave and grooved dorsally; their ends are attached 

 to the thyroid cartilage of the larynx bj;- rather long bars of cartilage. The small 

 cornua are short, 'wide, and flattened dorso-ventrally ; they are attached to short 

 bars which project from the junction of the body and thyroid cornua. The middle 

 cornu is a little longer than the small cornu, but is relatively slender; it is largely 

 cartilaginous in the young subject and does not ossify at either end. The great 

 cornu is a very slender rod, slightly enlarged at either end; the dorsal extremity is 

 attached to the hyoid process of the temporal by a rather long and wide bar of 

 cartilage. 



THE SKULL AS A WHOLE 



The length and the profile vary greatly in cUfferent subjects. Primitively 

 the skull is long — especially in its facial part — and the frontal profile is almost 

 straight. The condition is very pronounced in wild or semi-feral pigs, and exists 

 also — though in less degree — in the improved breeds during extreme youth. Most 

 of the latter are decidedly brachyccphalic when fully developed; the face is 

 "dished" in a pronounced fashion. The frontal region slopes sharply upward, 

 and the nasal region is shortened, and in some specimens even distinctly concave 

 in profile. The supraorbital foramina are about midway between the orbital mar- 

 gin and the frontal suture. The supraorbital grooves extend forward from the 

 foramina to the nasal region and turn ventro-laterally toward the infraorbital 

 foramina over the ridges which separate the nasal and lateral regions. 



The lateral surface is triangular when the mandible is included. The tem- 

 poral fossa is entirely lateral and its long axis is almost vertical. It is bounded 

 above by the nuchal crest, behind by the temporal crest, in front by the parietal 

 crest, and is marked off from the orbital cavity by the supraorbital process and a 

 curved crest which extends from it to the root of the pterygoid process. The 

 zygomatic arch is strong, high, and flattened from side to side. Its root is notched 

 dorsally and bears a projection ventrally. It curves sharply upward behind and 

 forms a pointed recurved projection above and in front of the external acoustic 

 meatus. The orbit is small. Its margin is deficient behind in the dry skull, thick 

 and rounded in front and below. The cavity is limited below by a ridge on the 

 frontal and lacrimal bones, and is separated by a crest from the temporal fossa. 

 The medial wall is perforated above by the orbital opening of the supraorbital 

 canal, and below by the optic and ethmoidal foramina; on its antero-inferior part 



