OUTLINES OF ZOOLOGY 



CHAPTER I 



GENERAL SURVEY OF THE ANIMAL 



KINGDOM 



In beginning the study of Zoology, it is natural and useful 

 to try to get a bird's-eye view of the " Animal Kingdom." 

 Without this, one is apt to miss the plan in studying the 

 details. But the survey can be of little service unless the 

 student has the actual animals in his mind's eye. 



Vertebrates, or Backboned Animals 



Mammals. — We begin our 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 

 general presence of convolutions on the front part of the 

 brain, the occurrence of a muscular partition or diaphragm 

 between the chest and the abdomen, and so on, as we shall 



