118 THE OCEAN WORLD. 



quit this difficult ground, trusting to make the special study of the 

 several types we shall have to describe more interesting. The group 

 of Polyps divide themselves into many classes, namely, the Alcyonidte, 

 the Zoanthina, the Discophora, and Ctenophora. It will be our 

 task to describe in succession the habits and characters of each of these 

 classes, dwelling on such species as appear to us to offer to the reader 

 most real interest. 



