This figure is intended to show that in the lion the contour of the face between the nasal bones and the cranial region is more flattened than in other felidæ, such as the tiger, jaguar, panther, and domestic cat. This difference is shown by comparison of this figure with the preceding one ([Fig. 58]). We are indebted to M. Tramond, the well-known naturalist, for the indication of this differential character which, from the artistic plastic point of view, is one of real interest.
This protuberance, prolonged on each side by the superior curved line of the occipital bone, is so much the more prominent as this bone bends sharply a second time, so as to form a third portion, which, looking forwards, forms part of the anterior aspect of the skull, and proceeds to articulate with the parietals. On this third portion is found a crest which, proceeding from the occipital protuberance, is continuous in front with the [parietal crests], to which we will again refer in speaking of the parietal bones.
On the inferior surface of the human occipital bone are found, at the level of, and external to, the condyles two bony elevations which bear the name of jugular eminences. They are long in quadrupeds, and constitute what are designated by some authors the styloid processes, but they must not be confounded with the processes of the same name which in the case of man form part of the temporal bone. These processes are very highly developed in the pig, horse, ox, and sheep.
In the ox, the occipital bone is deprived of the protuberance, and is not bent on itself in the anterior portion, neither does it form the most salient part of the skull; this latter, which is situated at the level of the horns, belongs to the frontal bone. In the pig, also, the occipital bone is not bent upon itself in its anterior portion, but forms the summit of the head. The occipital protuberance, hollowed on its posterior surface, rises vertically, and rests upon the parietal bone, with which it forms an acute angle.
The parietals, two separate bones in the dog and the cat, but fused in the median line in the ox, sheep, and horse, are of special interest in regard to the two crests which, in the carnivora, and also in the pig and the horse, occupy their external surface, and, after diverging from one another, are continued by a crest which crosses the frontal bone and ends at the external orbital process of the latter bone.
These crests, known as the parietal or temporal crests, recall both in position and relations the temporal curved line of the parietal bone of man. They contribute, as in the case of the latter, to the formation of the boundaries of the temporal fossa.
Fig. 60.—Skull of the Dog: Left Lateral Aspect.
1, Posterior surface of the occipital bone; 2, external occipital protuberance; 3, occipital condyle; 4, jugular process; 5, parietal bone; 6, frontal bone; 7, orbital process; 8, orbital cavity; 9, external auditory canal, in front of which is found the zygomatic process; 10, tympanic bulla; 11, superior maxillary bone; 12, intermaxillary or incisor bone; 13, nasal bone; 14, anterior opening of the cavity of the nasal fossæ; 15, malar bone; 16, lachrymal bone; 17, inferior maxillary bone; 18, condyle of the inferior maxillary bone; 19, coronoid process; 20, incisor teeth; 21, canine teeth; 22, molar teeth.