PHYLUM COELENTERATA 89 



which they occupy in life are readily recognizable. When the cups are incom- 

 plete laterally, so as to be fused into long furrows, the familiar "brain" corals 

 result. 



7. The homy corals and their relatives include the coral used in jewelry, the 

 organ-pipe coral, and other forms. The animals which secrete these skeletons 

 have eight feathery tentacles. 



8. The sea feathers, sea fans, etc. These plantlike horny skeletons are built 

 up by minute zooids, which occupy the small holes which will be found on closer 

 inspection distributed abundantly over the skeletons. 



