CLASSIFICATION OF MAMMALIA. 1 77 



subdivides into two great natural groups, according to the 

 modifications of the organs of touch. In the first of these 

 groups, a part of the digits, or last divisions of the members, 

 is left free for the exercise* of that faculty, the nail or claw 

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

 digits are inclosed in hoofs. 



For the convenience of treating of the different forms of the 

 unguiculate quadrupeds, Aristotle employs for their further 

 subdivision another system of organs ; viz. the teeth. His 

 first group or family is composed of those which have the 

 front teeth trenchant, or terminating in an edge, and the back 

 teeth terminated by a flattened surface, as the apes (Pithe- 

 coida), and the bats (Dermaptera) : his second family in- 

 cludes the quadrupeds with acuminated, trenchant, or carni- 

 vorous teeth, the Karcharodonta ; whilst the Rodent quadru- 

 peds, or Glires of Linnaeus, are also indicated by a negative 

 dental character. 



With respect to the hoofed or ungulate quadrupeds, Aristotle 

 continues to employ the organs for progressive motion for the 

 subordinate characters, and divides them into, 1st, the Po/y- 

 schidce, or multungulate quadrupeds, as the elephant, &c. ; 

 2nd, the Dischidce, or bisulcate quadrupeds, including, with 

 the ruminants, the hog ; 3rd, the Aschidce, or solidungulate 

 quadrupeds, as the horse and ass. 



The apodal vivipara, which form the third of Aristotle's 

 more comprehensive groups, has undergone no further divi- 

 sion by him. It embraces the Cetacea (Ketoda), and affords, 

 by its position in his system, one of the most striking exam- 

 ples of his sagacity and penetrating genius. 



It is to be observed, however, that although Aristotle has 

 arranged animals in groups which, in their relative value and 

 comprehensiveness, agree with the modern Classes, Orders, 

 Genera, Species, and Varieties, yet he applies to each of them 

 the same denomination ; viz. genos, or genus. 



From the time of Aristotle to the period of our great coun- 

 tryman Ray, we find no improvement or modification of any 

 consequence in this arrangement. The honour of having pro- 

 posed the second original scheme for the classification of 

 quadrupeds is due to him. This classification is given in a 

 tabular form in his 'Synopsis Methodica Animalium Qua- 

 drupedum,' and is as follows : — 



Zool. Mag. No. 6. 



