THE OAT AS A TYPE OF THE MAMMALS. 227 



form and in their adaptation to different niodes of life. 

 Confined to the earth, they are subjected to far greatei 

 perils than birds, and hence, though birds and mammala 

 appear at the same epoch in geological history, the mam- 

 mals have never perhaps got on so well as regards numbers 

 as the birds, since only 3100 species are known, and in the 

 United States there are abdut three species of birds to one 

 of mammals, there being only 310 species of the lattei 

 group. But with mammals it is quality and not quantity. 



They have had to depend more on their intelligence than 

 other animals for their success in life; they have had to 

 adopt, so to speak, many different professions to keep life 

 in their bodies. Hence there are moles, which burrow out of 

 sight after worms and insects; rats, mice, and squirrels, 

 which live by gnawing; bats, which fly in the air out of 

 harm's way; the whales and seals, which have taken to the 

 sea; the elephant, whose dependence is his trunk, tusks, 

 and colossal size; the horse and deer, which rely on their 

 legs to carry them out of danger; and the carnivorous 

 kinds, which live by stealthiness, cunning, boldness, and 

 agility; while the monkeys and apes lead an arboreal life. 

 The founders of the different orders have all, in the 

 course of time, by striking out into different paths in life, 

 won success each in its way, until we have, as the crowning 

 results, man, a being of mind and reason, his fore-limbs 

 converted into arms ministering to his thoughts. Man 

 also has a spiritual nature, which, in the best examples of 

 his race, dominates the animal nature he has in common 

 with the cred.tures below him. 



While the cat protects itself from its enemies by its 

 agility, its sharp teeth and claws, many mammals, espe- 

 cially those that chew the cud, as the deer, ox, rhinoceros, 

 etc., are armed with horns. There are two kinds of horns 

 — ^those with a bony core surrounded with a horny case of 

 skin, as in the deer; while in others, as the antelopes, sheep, 

 goats, and oxen, the horns are hollow. In most horned 

 mammals the horns are not shed; in the deer they drop off 



