104 



THE STRUCTURE OF THE HORSE 



do not possess it. In man it has attained its most 

 complete development, for not only is there a bridge, 

 but also a wall extending inwards from it, cutting off 

 almost completely the two cavities from one another. 



In front of the orbit a great, flat expanse, the 

 1 cheek,' extends quite to the fore-part of the face, 

 giving room for the long row of upper molar teeth, and 

 within, for the lodgment of the highly-developed organ 

 of smell. This is roofed over above by 'nasal bones' f n) 

 of great size, terminating in front by freely-projecting, 

 pointed, and somewhat decurved ends, which support 

 the well-developed external nostrils. The palate, which 

 forms the floor of all this part of the skull, is remark- 

 able for its great length and comparative narrowness. 

 The front end of the upper jaw consists of the united 

 c 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 

 premaxillee below and the nasals above, is the large, 

 irregular opening of the c anterior nares,' leading into a 

 great chamber or passage, divided into two by a vertical 

 median wall or septum. Through this chamber the air 

 passes in respiration to the c 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 



