Zootoka, or air-breathing vivipara, arc divided according to 

 the nature of their limbs into three sections:- -1st, Dipoda; 

 2nd, Tetrapoda ; 3rd, Apoda. The first comprised the biped 

 human race, the second the hairy quadrupeds, the third the 

 whale-tribe, in which the limbs answering to the legs of man 

 are wanting. 



The second of these divisions, which includes the great 

 majority of mammals, and is commonly regarded as the class 

 itself, Aristotle subdivides into two great groups, according to 

 the modification of the extremities. In the first group the 

 foot is multifid, and a part of the digit finger or toe is left 

 free for the exercise of the faculty of touch, the hard nail or 

 claw being placed upon one side only ; in the second group 

 the digits are inclosed in hoofs : these groups are recognised 

 in modern Zoology as the UNGUICULATA and UNGULATA. 



Aristotle, in the generalised expressions of his observations 

 on the various conditions of the teeth, has indicated subdi- 

 visions of the UNGUICULATA according to characters of the 

 dental system. One subdivision includes those quadrupeds 

 which have the front teeth trenchant, and the back teeth 

 flattened, viz. the Pitlieco'ida or Ape-tribe. Another subdi- 

 vision includes the quadrupeds with diversified acuminated 

 front teeth and interlocking serrated back teeth, viz. the Kar- 

 charodonta, or Carnivora ; whilst the animals now known as 

 ' Rodents ' are indicated by a negative dental character. 



With respect to the hoofed or Ungulate quadrupeds Aris- 

 totle in his generalisations on the organs of progressive motion 

 divides them into Dischidce, or bisulcate quadrupeds, and 

 Aschidce, or solidungulates, e. g. the horse and ass. 



The term Anepallacta, by which Aristotle signified the 

 animals in which the upper and lower teeth do not interlock, 

 is applicable to the herbivorous quadrupeds generally ; in 

 which the Amphodonta, or those with teeth in both jaws, 

 e. g. the horse, are distinguished by him from those in 

 which the front teeth are wanting in the upper jaw, e. g. 

 the ox. 



