160 



SKELETON OF THE DOG 



depression at the fronto-nasal junction, producing what is termed Ijy fanciers 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 pro])er and the extensive pterygo-palatine fossa. The 

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

 above downward. The infraorbital foramen is on its lower part above the third 

 cheek tootli In extreme brachycephalic breeds the orbit is relatively very large 



and the preorl)ital region 

 extremely short but high. 

 In the Ijulldog the lower 

 jaw protrudes beyond the 

 upper — a condition known 

 as prognathism. The op- 

 posite condition, brachy- 

 gnathism, is seen in the 

 dachshund. 



Striking features on 

 the basal surface of the 

 cranium are the width and 

 flatness of the basioccipi- 

 tal, the small size of the 

 paramastoid processes, the 

 large size and rounded 

 shape of the bulla ossea, 

 and the grooved form of 

 the articular surfaces for 

 the mandible. The pos- 

 terior 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 by 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 

 degrees; it is smallest in the greyhound, largest in extreme brachycephalic tyi^es, 

 e. g., bulldog, pug. 



The posterior or nuchal surface is somewhat triangular, with the base below. 

 The summit is formed by the occipital crest, which projects very strongly backward 

 in the large breeds. Below it there are two very distinct rough imprints for 

 muscular attachment. In somp skulls there is a thin median crest, in others a 

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



Fig. 126. — Skull of Brachycephalic Dog, Dorsal View without 

 Mandible. 



