XX INTRODUCTION 



This diagram illustrates the relations which the grand divisions 

 of Natural History bear toward each other: 



Natural History 



KINGDOMS (in a broad sense) bciences 



f Anthropology 



Animal j Zoology 



[ Paleontology 



^r i Botany 



Vegetable { „ i tI ±. 



\ raleobotany 



Mineral S°^°^T 



[ Mineralogy 



In its broadest sense. Natural History includes Chemistry and 

 Physics; but as that term is now commonly used, it is intended to 

 refer only to the life histories of living creatures. 



An Animal is a living creature belonging to the animal king- 

 dom; but this word is commonly, though incorrectly, used to 

 designate mammals alone. 



The animals of the world are so vast in number, and so varied 

 in form, that these lessons will treat only of the higher forms of life, 

 known as Vertebrates. 



A Vertebrate is an animal having (usually) a bony skeleton 

 and a spinal column or backbone, composed of a series of bones 

 called vertebrae. This division of life is called a Branch. 



The Branch Vertebrata is divided into seven grand divisions, 

 called Classes; which are known as Mammals, Birds, Reptiles, 

 Amphibians, Fishes, Myzonts, and Lancelets.^ 



A Mammal is a warm-blooded creature that brings forth its 

 young alive, and nourishes it with milk from its own body. All 

 land mammals, save a few species, are covered with hair; and all 

 sustain life by breathing air with the aid of lungs. Except man, 

 the mammals which live upon land are also called quadrupeds. 



'Two other Classes, Enteropneusts and Tunicates, are, by some modern zoologists, re- 

 garded as Vertebrates. These low forms, however, lack a complete backbone, or notochord, 

 and are therefore omitted. 



