CELENTERATA 



Madreporic Formations 



The madreporic formations which run the entire length of 

 the Red Sea coasts in various states of abundance, surround 

 the islands of volcanic origin with barriers or breakers, or 

 constitute the islands themselves, as in the case of the 

 Dahlaks. They are true masses of prevalently colonial 

 madreporaria zoantharia (they are rarely isolated), belong- 

 ing to numerous species and forming strange original shapes 

 of soft delicate colours. They have a heavy external calcareous 

 structure on which the polyps of the colony sprout from their 

 own cups. 



Of the free forms, that is, those simply resting on the sea 

 bottom, are the fungias (mushroom coral) of the typical 

 roundish shape (ciclolites, patella, etc.) or of the longish, 

 shoe shape, the Ehrenbergi. They exist among the bushy or 

 tree-like formations of the acropora, pocillopora and 

 madrepora of the most varied species, of a yellow, pink or 

 violet colour. 



Great quantities of galazaea with their clusters of little 

 tubes, cover vast areas in the channels between the islands, 

 or in other sheltered zones, in depths up to three feet or 

 little more. These are interspersed with the mussae. In the 

 open spaces on the sand, the so-called cerebral-form madre- 

 pore are found — montipora, meandrina, prionastraea, por- 

 ites, etc. 



Still in the heart of the madreporic formations, belonging 



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