CLASS MAMMALIA. 75 



The cranium of the mammalia is divided into three 

 compartments. The anterior is formed of the two 

 frontal bones and the ethmoid ; the intermediate by 

 the parietal bones and the sphenoid; and the pos- 

 terior by the occipital. Between the occipital bones, 

 the parietals, and the sphenoid, are inserted the 

 temporal bones, a part of which properly belong to 

 the face. 



In the foetus the occipital bone is divided into four 

 parts ; the body of the sphenoid into two, and three 

 of its pairs of alee are also separated. The temporal 

 bone is divided into three, one of which serves to 

 complete the cranium, another to close the labj^rinth 

 of the ear, and the third to form the sides of its 

 cavity. These parts, of the bones of the cranium 

 unite more or less quickly in the different species, 

 and end by perfect union in the adult subject. 



The face is formed^ by two maxillary bones, be- 

 tween which the nasal canal passes ; they have the 

 two intermaxillary bones in front, and the two pala- 

 tines behind ; between them descends the single 

 lamina of the ethmoid bone denominated the vomer. 

 At the entrance of the nasal canal are the bones 

 proper to the nose; to the external sides of this 

 canal their inferior horns adhere; their superior ex- 

 tremities or horns which occupy its upper and pos- 

 terior part belong to the ethmoid. The jugal, or 

 cheek bone, of each side unites the maxillary bone 

 to the temporal, and often to the frontal bones. 

 Lastly, the lachrymal occupies the internal angle of 

 the orbit, and sometimes a part of the cheek. 



