196 



SKELETON OF THE DOG 



marked depression at the fronto-nasal junction, producing what is termed by fan- 

 ciers the "stop" of the face. 



On the lateral surface the great extent of the temporal fossa is seen. The 

 orbit communicates freely with the fossa, the posterior part of the orbital margin 

 being absent in the dry skull. The axis of the orbital cavity forms a much smaller 

 angle with the median plane than in the horse and ox. A distinct crest marks the 

 limit between the orbital cavity and the extensive pterygo-palatine fossa. The 

 preorbital region is somewhat triangular, concave in its length, and convex dorso- 

 ventrally; the infraorbital foramen is on its lower part above the third cheek tooth. 

 In extreme brachy.cephalic breeds the orbit is relatively very large and the preor- 

 bital region extremely short but high. In the bulldog the lower jaw protrudes be- 

 yond the upper — a condition known as prog- 

 nathism. The opposite condition, brachygna- 

 thism, is seen in the dachshund. 



Striking features on the basal surface of 

 the cranium are the width and flatness of the 

 basilar part of the occipital bone, the small size 

 of the paramastoid processes, the large size and 



Fig. 214. — Ski-ll of Dolichocephalic Dog; 

 Dorsal View, 



Fig. 21.5. — Skull of Brachycephalic Dog; Dorsal View. 



rounded shape of the bulla ossea, and the grooved form of the articular surfaces 

 for the mandible. The posterior nares are long and narrow and are not divided 

 by the vomer. The hard palate is usually about half the length of the skull. It 

 is commonly marked bj"^ a median crest or rough line, and on each side are the 

 anterior and accessory palatine foramina and the palatine grooves. The width 

 is greatest between the fourth pair of cheek teeth, and here there is in most skulls 

 a pronounced depression on either side. The length, width, and contour vary 

 greatly in different breeds. 



The angle of divergence of the rami of the mandible varies from 25 to 30 de- 

 grees; it is smallest in the greyhound, largest in extreme brachycephalic types, 

 e. g., bulldog, pug. 



The nuchal surface is somewhat triangular, with the base ventral. The sum- 

 mit is formed by the nuchal crest, which projects very stronglj^ backward in the 

 large breeds. Below it there are two verj' distinct rough imprints for muscular 

 attachment. In some skulls there is a thin median occipital crest, in others a 

 rounded elevation. Laterally are the temporal crests and the mastoid processes. 



