48 VERTEBRATA. MAMMALIA. 



and partly from their weakness, those of the present 

 group possess with the sanguinary appetite for flesh, 

 the force necessary to obtain it. They have four 

 large and sharp canines, usually called tusks, and 

 six incisors in each jaw ; the molars must be de- 

 scribed more particularly. The molars next to the 

 canines are the most trenchant, and are named false 

 molars ; next comes a molar larger than the rest, 

 called a lacerator, usually furnished with a tuber- 

 culous heel ; and behind it, one or two small teeth 

 that are quite flat, called tuberculous teeth. As the 

 power of eating flesh is dependent on the trenchant 

 character of the teeth, the nature of their diet may 

 be readily seen by observing the proportion which 

 the tubercled surface bears to that portion which 

 has a cutting power. Those genera which have the 

 fewest false molars, and the shortest jaws, are the 

 most exclusively carnivorous. 



There is also a great difference in the manner of 

 walking. Some genera, like all those we have yet 

 considered, place the whole sole of the foot to the 

 ground, from the heel to the toes. But the greater 

 number, raising the heel, walk only on the toes, and 

 in these the greater part of the sole is covered with 

 hair. These are swifter than the former ; and it is 

 a curious circumstance that when man runs swiftly, 

 he does not put his heel to the ground at all. To 

 the former of these divisions has been applied the 

 term Plantigrade, to the latter Digitigrade.* 



* Planta, the sole and gradior^ to step; (liyiius^o. finger or toe. 



