74 



CORAL AND ATOLLS 



previously is true for them all, and each, though highly 

 characteristic as an inherent growth-form for a certain coral, 

 may be assumed by many other corals. 



One method of division that is important among corals 

 with zooids of equal reproductive value is the type charac- 



FiG. 12. 



Example of a Coral Colony growing as an 

 Encrusting Layer. 



teristic ot the Meandrinm. In these corals the complete 

 separation of the divided zooids is never carried out by the 

 calcareous partition-walls, and so a more or less linear series of 

 zooid mouths is formed. Tentacles fringe the margins of this 

 series, and the resulting skeleton exhibits those well-known 

 fissure-like markings that have given museum specimens the 

 name of " brain-corals." 



Now even such a highly characteristic type of division as 



