172 SKELETON OF THE PIG 
maxilla. In the adult the frontal sinus extends into the posterior part of 
the bone. 
The lacrimal bone is very sharply bent. Its facial surface presents a deep 
depression, surmounted by a ridge or tubercle. On or close to the orbital margin 
are two lacrimal foramina which lead to the lacrimal canals. The orbital surface 
presents a fossa in which the inferior oblique muscle of the eyeball arises, and its 
lower part bears a crest, which is crossed obliquely by a vascular furrow. The 
dorsal border articulates with the frontal only. The bone concurs in the formation 
of the maxillary sinus. 
The malar bone is strongly compressed from side to side. Its facial surface 
is small and presents a fossa which is con- 
tinuous with the depressions of the maxilla 
and lacrimal. The orbital surface is still 
smaller and is smooth and deeply grooved. 
The zygomatic process is very extensive, 
especially in the vertical direction. Its 
lateral surface is convex and free, and 
bears a rough eminence in its middle. Its 
medial surface is concave; it is over- 
lapped in front by the maxilla, and in the 
remainder of its extent is free and smooth. 
The dorsal border is thick and rounded in 
front, where it forms the lower part of the 
orbital margin; behind this it forms an 
extensive notch which receives the zygo- 
matic process of the temporal. (It might 
be regarded as dividing into frontal and 
temporal branches.) The ventral border 
is convex and becomes thinner behind. 
The turbinate bones resemble those 
of the ox. The dorsal turbinate is, how- 
ever, relatively longer, less fragile, and 
more firmly attached to the nasal bone. 
There is no middle turbinate. 
The vomer is very long. The anter- 
ior extremity reaches to the body of the 
premaxilla or very close to it. The ven- 
tral border is received into a groove 
formed by the nasal crest of the maxillee 
and palatine bones and in front by the 
palatine processes of the premaxillee. The 
ramus; C, condyle; ‘D, coronoid process; 1, 2, 3,in- Posterior border is concave, thin, ame 
cisor teeth; 4, canine tooth; 5, 6, 7, premolar teeth sharp. 
SOUS LEO) SIDE cM re SAI The os rostri (or prenasal bone) is 
situated in the snout between the nostrils. 
It has the form of a short, three-sided prism. The dorsal surface is convex and is 
notched at each end. The lateral surfaces are concave, smooth, and converge 
below, forming a grooved ventral border. The posterior surface is triangular, 
notched centrally, and rough laterally. The anterior surface is deeply pitted and 
is surrounded by an irregular sharp border. 
The mandible is very strong, and differs very much from that of the horse or 
ox. The body narrows decidedly in front; the lingual surface is deeply concave; 
the mental surface is strongly convex, slopes downward and backward, and forms 
a distinct prominence (Tuber mentale) at the point of divergence of the rami. 
Fig. 181.—Manp1BLe or Pia; Dorsat VIEW. 
A, Body; B, B’, horizontal and vertical parts of 
