CLASSIFICATION OF ANIMALS. 



17 



is another chain of bones of a slighter make along the 

 back, their spinous processes being the frame-work of the 

 fins of the back. 



7. The turtle or tortoise tribe have the body covered 

 with an upper and an under bony plate. But they have 

 connected with the under side of the upper plate a true 

 vertebral column. You see this in Fig. 6. The lower 



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Fig. 6.— Skeleton of the Turtle. ^ 



plate is removed from this skeleton of a turtle to show 

 the vertebral column in its whole length. 



8. This chain or column extends out to the end of the 

 turtle's tail. It is so with all the tails of four-footed an- 

 imals. In the necks of birds, and generally of quadru- 

 peds, and in the tails of the latter there is quite a free 



