Indeed, let us suppose that to a clay model of a human head we wish to give the aspect of the head of a quadruped. We should elevate the occiput; and then, taking hold of the lower part of the face, we should lengthen it, not in a direction precisely antero-posterior, but downwards and forwards. It is obviously this latter procedure which, on the other hand, is carried out when a person wishes to give to his own face some resemblance to the muzzle of a quadruped.
It is true that, in the position we have adopted, the face is directed obliquely downwards and forwards, and that there may result a certain confusion in describing the position of its different parts. On this account, with the object of not making complications, we purpose, for the present, to substitute, for example, for the term ‘antero-superior’—which when speaking of the position of the forehead and nose would be more exact—the term ‘anterior,’ which is sufficiently comprehensible. The mouth will be, for the same reason, referred to as being situated at the inferior part of the face, and not the antero-inferior.
The Skull.—The elevation of the cranial region becomes especially appreciable when we examine the occipital bone. Before verifying this fact, it is not superfluous to recall the general arrangement which this bone presents in the human skull. A portion of the occipital bone occupies the base of the skull; but this base in man is horizontal; to this region succeeds the shell-shaped portion of the occipital bone, which, passing vertically upwards, forms with the preceding portion an angle situated at the level of the external occipital protuberance, and of the curved line which starts from it on each side. In animals a portion of the occipital bone is horizontal, it is true; but this bone being sharply bent at the level of the occipital foramen and condyles, the result is that the portion which surmounts these latter looks backwards, and is limited above by the external occipital protuberance, which forms the culminating point of the skull; this point is situated between the ears.
Fig. 58.—Skull of one of the Felidæ (Jaguar): Left Lateral Aspect.
1, Posterior surface of the occipital bone; 2, external occipital protuberance; 3, condyle of the occipital bone; 4, jugular process; 5, parietal bone; 6, frontal bone; 7, orbital process; 8, orbital cavity; 9, squamous portion of the temporal bone; 10, external auditory canal, in front of which is situated the zygomatic process; 11, tympanic bulla; 12, superior maxillary bone; 13, intermaxillary or incisor bone; 14, nasal bone; 15, anterior orifice of the nasal cavity; 16, malar bone; 17, ungual or lachrymal bone; 18, inferior maxillary bone; 19, condyle of the inferior maxillary bone; 20, coronoid process; 21, incisor teeth; 22, canine teeth; 23, molar teeth.
Fig. 59.—Skull of the Lion: Left Lateral Aspect.