Birds Mammals. 8^ 



ral adaptation by which the bird occupies a distinct 

 place in the animal kingdom, there are numberless 

 special adaptations apparent here, by which every 

 is fitted for its peculiar condition of life. 

 The form of the bird is as perfect for the air as that 

 of the fish is for the water. 



Its bones are hollow, to give it lightness. Its 

 lung capacity is increased to meet the great draft 

 made upon its powers in living. To give it strength 

 of flight, the musck-s are thickened and strengthen- 

 ed, absolutely piled up, around the base of the 

 wing. Need I speak of the line adjustment of 

 every feather, the eagle's eye, and the varied form 

 of foot and bill to meet the different instincts and 

 conditions of life ? 



Among the mammals, we find the highest forms 

 approaching man in perfection, and therefore pre- 

 senting those general adaptations which we have 

 already considered when treating of him. But 

 there are curious forms and varied conditions of 

 life which demand relations entirely distinct from 

 those found in man. The mole is made to pierce 

 the earth, the whale to sport jn the waters, the 

 elephant for the jungles of the torrid zone, the white 

 bear for the icebergs of the polar seas ; each one 

 is fitted by instinct, power of endurance, and struc- 

 ture, for the place he is to occupy. 



The otter is fitted for both land and water, and 

 has a coat that the water never penetrates. The 

 seal has no protection against the water from his 

 fur ; but he and the -whale are both clothed with a 



