200 



SKETCH OF THE HISTORY OF MAMMALIA. 



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136. — Skull and Lower Jaw of Walrus. 



The immense development of the alveoli of these canines 

 gives a swollen appearance to the face, which is increased 

 by the tumid character of the lips, covered with thick 

 wiry moustaches. The dentition is as follows : — Upper 

 jaw : incisors four, of which the two middle are deciduary, 

 falling out at an early period ; the two lateral have the 

 character of molars. Of the enormous canines we have 

 already spoken. Molars on each side four, cylindrical, 

 short, and obliquely truncate. Lower jaw : incisors want- 

 ing; canines wanting; molars as in the upper jaw. The 

 lower jaw is not only small in proportion to the general 

 volume of the skull, but is compressed as it proceeds, in 

 order to fit in between the huge canines of the upper 



