212 



MAMMALIA, 



Trichechus (Linn.). Walrus. Lower jaw without 

 cutting or canine teeth ; canines of the upper jaw 

 arching downwards, in the form of projecting 

 tusks ; muzzle greatly enlarged. 



T. rosmarus. Fig. 337 ; ^ n. s. 



337 



Halichcerus (Nilsson). Four cutting- teeth to 

 each jaw; molars simple, the lower ones with a 

 minute knob before and behind ; head fiat ; muzzle 

 deep, obliquely truncate. 



H. gryphus. Fig. 338 ; Jg- n. s. 



