MAMMALIA. 331 



in this branch of science has materially enlarged our know- 

 ledge of the structure, the functions, and the physical his- 

 tory of man: subjects with which our welfare has obviously 

 the closest and most intimate relation. 



The principle of analogy which prevails so generally in 

 the inferior departments of the animal creation, may be also 

 traced in the class mammalia; for we always fmd its influ- 

 ence more conspicuous in proportion as the objects compre- 

 hended in the natural series of beings are more numerous 

 and more diversified. Scarcely any of the great natural as- 

 semblages of animals exhibit more variety in their habits 

 and modes of existence, than the one we are now examining. 

 Each race has. its peculiar destination with regard to the 

 kind of food by which it is nourished, and the means by 

 which that food is obtained. The carnivorous tribes wase 

 war with the larger animals, whom they either spring upon 

 unawares, or openly pursue and overpower, displaying the 

 savage energies of their nature, in practising all the arts of 

 ferocious and sanguinary destruction. Others, intent on 

 meaner prey, resort to divers stratagems for its possession; 

 some are designed to feed chiefly on the mollusca, and others 

 swallow insects only. The numerous tribes which are 

 formed to subsist on vegetable food exhibit, in like manner, 

 a great diversity of constructions, adapted to the particular 

 nature of that subsistence, whether it be herbage, or the 

 leaves of trees, or fruits, or seeds, or the coarse fibres of the 

 wood and bark. While all are gifted with powers to ob- 

 tain the nourishment they require, those that have not been 

 armed with weapons of attack, are still provided with in- 

 struments of defence, or with means of flight. Each has its 

 respective sphere of operation; and to each has its appropri- 

 ate soil, habitation, climate, and element been assigned. 



It is easy to conceive that all these various circumstances 

 must lead to great diversities in the apparatus for mastica- 

 tion and for digestion, in the organization of the senses, in 

 the construction of the instruments of locomotion and of pre- 

 hension, and in the general form of the body to which these 



