112 THE STRUCTURE OF THE HORSE. 



ends, which support the well-developed external nos- 

 trils. The palate, which forms the floor of all this 

 part of the skull, is remarkable for its great length 

 and comparative narrowness. The front end of the 

 upper jaw consists of the united " premaxillary 

 bones," which expand and curve down to form the 

 semicircular border supporting the large incisor 

 teeth. In the middle line, in front, between the pre- 

 maxillae below and the nasals above, is the large, ir- 

 regular opening of the " anterior nares," leading into 

 a great chamber or passage, divided into two by a 

 vertical median wall or septum. Through this cham- 

 ber the air passes in respiration to the "posterior 

 nares," a smaller opening at the base of the skull 

 behind the palate, and in the upper part of it is 

 placed the sponge-like mass of bones which support 

 the terminations of the olfactory nerves, constituting 

 the organ of smell. Before leaving the cranium, the 

 " glenoid " cavities, or, rather, surfaces (#), to which 

 the two branches of the mandible are articulated, 

 must be mentioned. They are placed just below the 

 hinder end of the zygomatic arch. They are wide 

 transversely, concave from side to side, convex from 

 before backwards in front and hollow behind, and 

 bounded posteriorly at the inner part by a promi- 

 nent " post-glenoid n process, which effectually pre- 

 vents the jaw from being dislocated backwards. 



