194 INTRODUCTION. 



Accordingly, the names of the orders, as instituted by Cuvier, refer 

 sometimes to the characters of the extremities, sometimes to those of the 

 dentition, and sometimes to other organic peculiarities ; but, it is clear 

 that no one structural modification ought to be considered in an isolated 

 point of view, nor can the definition of a group rest solely upon a single 

 character. In some groups, the organs of locomotion form the most pro- 

 minent and tangible grounds of distinction, and suggest the appellation as 

 Quadrumana, and Cheiroptera ; in others, the condition of the dental 

 system gives rise to the appellation as Carnivora, Insectivora, Rodentia, 

 Edentata. The teeth, indeed, as connected with the form of the skull, the 

 state of the digestive apparatus, and the nature of the diet, and, conse- 

 quently, as involving the arrangement of the whole animal machine, 

 cannot be regarded as taking a second-rate place among the great cha- 

 racters by which we are to be guided in the classification of the Mam- 

 malia ; nevertheless, they ought not to claim exclusive attention. 



It is not, then, from one point of structure that the laws are to be 

 deduced on which the orders and families of Mammalia are to be founded ; 

 but from a careful estimate of the totality of organization, and the harmony 

 of the parts with each other, proclaiming the direction of instincts, as 

 to habits, manners, and food, and indicating, also, the ratio of intelligence ; 

 while the subordinate division into genera is decided by characters of 

 minor importance, such as the number of toes or of teeth, the relative 

 proportions of the limbs, the quality of the external clothing, &c. 



