17 



three coccygeal vertebrae. These ca\'ities conininiiicate with the 

 brain by narrow passages, through one of which the optic nerve 

 passes. 



On each side, below the eye, are two closed cavities known as 

 the superior and inferior maxillary sinuses: in the lower third of 

 the skill are found the nasal chambers extending from the nos- 

 trils backward to the pharynx, and separated by a thin partition 

 of bane and cartilage, the floor of these cavities forming the 

 roof of the mouth. From the orbital fossae the skull gradually 

 becomes narrower and terminates a short distance below the 

 nostrils in the premaxilla, which contains the six upper incisor 

 teeth, which, vrith the corresponding teeth in the lower jaw. 

 form the anterior boundary of the mouth, which extends back- 

 ward to the iDharynx, On the posterior upper portion of this 

 ca^i-ty are found six molar teeth on each side, and that portion 

 of the jaw between them and the incisors is called the interdental 

 space. Situated on each side near to the incisor teeth in this 

 space are found, in the male, the tushes or canine teeth. 



The inferior maxilla, or lower jaw, a bone whose two segments 

 are firmly united anteriorly, diverges backward somewhat in 

 the form of a letter V, each branch terminating superiorly in an 

 articulated surface which unites it to the skull proper. The 

 diverging branches of the jaw, include a space appropriately 

 called the maxillary space. Found in the united or front part of 

 this bone are the inferior incisors, and in the male the canine 

 teeth, and in the branches the inferior molars or grinders, which 

 correspond with those of the upper jaw. 



The space between the molars and incisors is the same as that 

 in the upper jaw. 



The front leg is composed of the following-named bones and 

 joints, given in order from above downward: Scapula and 

 humerus, forming the shoulder joint: humerus, radius, and 

 ulna, forming the elbow joint: radius, carpus (seven or eight 

 S-uall bones), and metacarpus, forming the knee joint; metacar- 

 pal, OS suffraginis, and two sesamoids, forming the fetlock joint; 

 03 suffraginis and os coronse, forming the pastern joint; os 

 coronae. os pedis, and os na^-icularis, forming the navicular or 

 coifin joint. ' 



The hind leg is composed of the follo^-ing bones: The pehus, 

 situated underneath the sacrum and part of the coccygeal 



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