CLASSIFICATION OF ANIMALS. 15 



of the bones that you feel as you pass your finger up and 

 down the middle of the back. Each of these bones is 

 called a vertebra (plural vertebrae). Therefore all ani- 

 mals that have this column or chain of bones are called 

 vertebrate animals. It is varied, as you will see, in dif- 

 ferent animals to suit different circumstances, and yet it 

 is in essential points the same thing in all. 



4. This vertebral column is found in all quadrupeds, 

 as you see in this skeleton of a camel. The dark part 



Fig. 3. Skeleton of the Camel. 



of the figure shows the full size of the animal. You ob- 

 serve that the spinous processes of the vertebrae of the 

 back make a high, strong ridge. This is because to them 

 are fastened the muscles that hold up the heavy neck and 

 head. 



5. Birds have this column, as you see in Fig. 4 (p. 16), 

 the skeleton of an ostrich. Here there are very many 

 more vertebras in the neck than there are in the neck of 



