194 



SKELETON OF THE DOG 



of the lateral boundaries of the posterior nares. The lower and posterior borders 

 are free and at their angle of junction there is a variable hamulus. 



The nasal bones are (in most breeds) long and wider in front than behind. 

 The facial surface is variably concave in its length and is inclined toward the 

 median suture so as to form a central groove. The medial borders turn downward 

 and form an internal nasal crest which becomes very prominent behind. The pos- 

 terior parts fit into a notch formed by the frontal bones. The anterior ends form 

 an almost semicircular nasal notch. 



The lacrimal bone is very small. The facial part extends very little or not 

 at all beyond the orbital margin. The orbital surface is small and triangular, 

 and presents the entrance to the lacrimal canal. 



The large zygomatic process constitutes the bulk of the malar bone. It is 

 very long and is strongly curved. The dorsal border is convex, free in front, where 

 it forms part of the orbital margin, beveled behind for articulation with the similar 

 process of the temporal bone. Between these it bears an eminence, the processus 

 frontalis, to which the orbital ligament is attached. The body of the bone may be 

 considered to consist of a lacrimal process directed dorsally and fitting in between 



Incisor Canine Premolar 

 teeth tooth teeth 



Symphyseal 

 surface' 



Mandibular 

 foramefi 



Coronoid 

 process 

 Mandibu- 

 lar notch 

 Condyle 



Angular 

 process 



Fig. 213. — Right Half of Mandible of Dog; Medial View. 



the lacrimal and maxilla, and a maxillary process directed ventrally. The facial 

 surface is convex. 



The dorsal turbinate bone is in its anterior part a simple plate, attached by 

 one edge to the nasal bone; it curves ventro-medially, and its free border is thick- 

 ened and everted. The posterior part is wider and resembles the ethmoturbinates, 

 with which it is connected. 



The ventral txirbinate bone is short and very complex. It is attached to the 

 nasal surface of the maxilla by a basal lamina, which divides into two secondary 

 lamellae. The latter detach numerous tertiary lamellae, which are coiled and have 

 thick free edges. 



The vomer is not in contact with the posterior part of the floor of the nasal 

 cavity, and does not divide the posterior nares. The posterior end is narrow and 

 deeply notched. Near the posterior nares the two plates curve outward and join 

 the palatine bones and assist in forming the lamina transversalis. 



The two halves of the mandible do not fuse completely even in old age, so that 

 there is a permanent symphysis mandibulse. The body presents six alveoli for the 

 incisor teeth and two for the canines. The incisor alveoli increase in size from first 

 to third. The canine alveoli extend deeply downward and backward. The rami 

 diverge less than in the pig. The ventral border of the horizontal part is convex 

 in its length and is thick and rounded. The alveolar border is slightly concave in 



