CORAL BUILDERS, 



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depositing within themselves a skeleton of coral, the 

 coral-making species are fixed (fig. 48), this deposit 

 taking place in the sides, and lower part of the polyp, 

 leaving the disk and stomach fleshy. The internal 

 septa secrete radiating plates of coral between each 

 pair of septa, so 

 that when dead, 

 and the fleshyparts 

 are dissolved away, 

 these radiating 

 plates represent the 

 radiating septa in 

 the internal cavity 

 of the anemone. 

 The calcareous, or FIG 4 g._ C ARYOPHYLLiA SMITHII. 

 persistent coral 



skeleton, which is left when all the fleshy parts are 

 gone is called the corallum, and is, in fact, the coral. 

 A few of the species in this group are simple, and the 

 coral produced is the secretion of single polyps. 

 This is the case in the Fungia family in which the 

 numerous radiating plates resemble the gills of a 

 mushroom inverted, whence their name is derived. 

 They are by no means small species, but will attain 

 to more than a foot in length, the corallum, or 

 skeleton, being a common object in museums. They 

 are found in coral-reef seas lying on the bottom, but, 

 unlike most coral-secreting species, are not fixed 



