OUTLINES OF ZOOLOGY. 



CHAPTER I. 



GENERAL SURVEY OF THE ANIMAL 

 KINGDOM. 



In beginning the study of Zoology, it seems useful to take 

 a general survey of the " Animal Kingdom." Without some 

 such bird's-eye view — necessarily superficial — one is apt to 

 lose sight of the plan in studying the details. But the 

 survey can be of little service unless the student has the 

 actual animals before him, or in his mind's eye. 



Vertebrates, or Backboned Animals. 



Mammals. — We naturally begin a survey with the animals 

 which are anatomically most like man — the monkeys. But 

 neither we nor the monkeys are separated by any structural 

 gulf from the other four-limbed, hair-bearing animals, to 

 which Lamarck gave the name of Mammals. For although 

 there are many different types of Mammals — such as 

 monkeys and men ; horses, cattle, and other hoofed quad- 

 rupeds ; cats, dogs, and bears ; rats, mice, and other rodents ; 

 hedgehogs, shrews, and moles, and so on — the common 

 possession of certain characters unites them all in one 

 class, readily distinguishable from Birds and Reptiles. 



These distinctive characters include the milk-giving of 

 the mother mammals, the growth of hair on the skin, the 



