140 THE HARMONIES OF NATURE. 



The larval zooids are formed upon a type quite different from 

 that which characterises the adults, for instead of a radial 

 symmetry they exhibit a bilateral, the two sides being precisely 

 alike, and each having a ciliated fringe along the greater part or 

 the whole of its length. Such are the changes they undergo in 

 the progress of their growth, that in the fully developed star-fish 

 and sea-urchin the only part retained is a portion of the stomach 

 and intestine, which is pinched off, so to speak, from that of the 

 larval zooid by the animal's forcible contractions. 



Many of the details of this wonderful history are still unknown, 

 and undoubtedly belong to the most interesting secrets of the 

 life of the seas. 



