CHAPTER XIV 



ANTIIOZOA {coyTINL'ED) : ZOANTHAKIA 



Sub-Class 11. Zoantharia. 



The Zoantharia exhibit a great deal more diversity of form and 

 structure than the Alcyonaria. The sub-class is consequently 

 difficult to define in a few words, and it may be taken to include 

 all the Anthozoa which do not possess the typical Alcyonarian 

 characters. 



All the orders, with the exception of the Antipathidea and 

 Zoanthidea, contain genera of solitary zooids, and the orders 

 Edwardsiidea and Cerianthidea contain no genera that form 

 colonies. In the Madreporaria, Zoanthidea, and Antipathidea, 

 on the other hand, colonies are formed composed of a very large 

 number of individuals which frequently attain to a very great 

 size. The term " Sea-anemone " is commonly used in writing 

 about the solitary Zoantharia which do not form any skeletal 

 structures, and the term " Coral " is applied to all those Zoantharia 

 which do form a skeleton. 



In a scientific treatise, however, these popular terms can no 

 longer be satisfactorily employed. The " Sea-anemones " exhibit 

 so many important differences in anatomical structure that they 

 must be placed in at least three distinct orders that are not 

 closely related, and the organisms to which the term Coral has 

 been applied belong to so many organisms — such as Alcyonaria, 

 Hydrozoa, Polyzoa, and even Algae — that its use has become 

 indeterminate. 



Whilst these terms must disappear from the systematic part 

 of Zoology, they may still be employed, however, in the description 

 of a local fauna or coral reef to signify the soft solitary zooids on 



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