362 METAMOKPHOSES OF ANIMALS. 



would be found in a similar state of preservation. As the 

 apophyses are the only bony portions of their vertebral column, 

 they alone would be preserved. Indeed, fossil sturgeons are 

 known, which are precisely in this condition. 



577. From the fact above stated, we may conclude that 

 the oldest fossil fishes did not pass through all the metamor- 

 phoses which our osseous fishes undergo, and consequently 

 that they were inferior to analogous species of the present 

 epoch, which have bony vertebrae. Similar considerations 

 apply to the fossil Crustacea and to the fossil echinoderms, 

 when compared with their living types ; and it will probably be 

 true of all classes of the animal kingdom, when they are fully 

 studied as to their geological succession. 



