MAMMALIA 1517 



sary. It is from the mammae that this class derives 

 its name, and being a character peculiar to it, they 

 distinguish it better than any other that is external. 



The variable characters which form essential dif- 

 ferences among the mammalia are taken from the 

 organs of touch, on which depends their degree of 

 ability or address, and from the organs of mandu- 

 cation, which determine the nature of their ailment, 

 and are all closely connected, not only with every- 

 thing relative to the function of digestion, but also 

 with a multitude of other differences relating to 

 their intelligence. 



The degree of perfection of the organs of touch 

 is estimated by the number and the pliability of the 

 fingers, and from the greater or less extent to which 

 their extremities are enveloped by the nail or the 

 hoof. 



A hoof which completely envelops the end of the 

 toe blunts its sensibility, and renders the foot in- 

 capable of seizing. 



The opposite extreme is when a nail, formed of 

 one single lamina, covers only one of the faces of 

 the extremity of the finger, leaving the other pos- 

 sessed of all its delicacy. 



The nature of the food is known by the grinders, 

 to the form of which the articulation of the jaws 

 universally corresponds. 



To cut flesh, grinders are required as trenchant 

 as a saw and jaws fitted like scissors, having no other 

 motion than a vertical one. 



For bruising roots or grains flat-crowned grinders 

 are necessary, and jaws that have a lateral motion; 



