CLASSIFICATION OF ANIMAIS. E5 
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 vertebre). 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 vertebre 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 vertebra in the neck than there are in the neck of 
