MADREPORARIA. 



479 



and always very solid. Massive specimens of Porites are 

 sometimes fifteen feet in diameter. In the true Madre- 

 pores (Fig. 722), the cells of the coral are deep, and these 

 corals spread and branch into the most beautiful and varied 

 forms, and the polyp at the end of a branch is always 

 larger than the others. 



In the great group of the Astrseacea the tentacles occur 



FIG. 722. 



Madrepore, Madrepora aspera, Dana. Right-Laud branches alive. 



FIG. 725. 



FIG. 723. 



FIG. 724. 



Cladocora Jlexuosa, Ehr. 

 FIG. 726. 



Pocillopora cccspi- 

 tosa, Dana. 



Porites flexunsa, Dana. 



Mitandrina gracilis, Dana. 

 Small piece of a large mass. 



