96 CLASS AVES. 



located in their exclusive domains. Thus it has been allotted 

 to the quadruped to live on the earth, to the fish to cleave the 

 depths of ocean, to the bird to wing the wide regions of the air, 

 and it is not a little remarkable that each of these beings bear, 

 in their respective natures, no small analogy to the element 

 which destiny has prescribed for their abode. 



The fish, continually immersed in a cold and relaxing fluid, 

 possesses a softer texture of conformation, a moist temperament, 

 and a great flexibility of organs, in accordance with the natural 

 inconstancy of the waters by which he is surrounded. The qua- 

 druped, situated on a terrestrial and stony soil, has contracted 

 a solidity of organization, and a weight of limbs, which retain 

 him attached to the earth ; while the bird, continually travers- 

 ing the subtler atmospheric medium, inhaling in expansive 

 lungs, and through their appendages and prolongations, a con- 

 siderable quantity of air, which penetrates his entire system, 

 even to his bones and feathers, must, of necessity, acquire the 

 peculiar hghtness, buoyancy, and activity which distinguish 

 him. 



We may observe, indeed, this adaptation of which we are 

 speaking in various proportions in animals, according to the 

 nature of their more usual habitat. Do we not find that water- 

 fowl, retaining in their bodies a great quantity of the humid 

 principle, are much more gross and heavy, than the agile and 

 exclusive tenants of the air? Have not the gallinae, such as 

 the turkey, partridge, hen, &c., constantly living on the earth, 

 contracted a weight of body, to which the races habituated to 

 live in the high atmospheric regions are strangers ? It is thus 

 we find the aquatic mammifera, such as the hippopotamus, the 

 lamantin, and the seal, much more stupid and heavy than those 

 which live on dry ground. Even among these last, how much 

 more lively and delicate are the gazelle, the chamois, the wild 

 goat, and other natives of the mountains, than the quadrupeds 

 of the valley and the plain ? Even in the fish, which prefer 

 light and limpid streams with sandy bottom, we find a texture 



