COKALS AND CORAL MAKERS. 37 



be found to liave two mouths. This is the first step in the 



ASTR.KA I'ALI.IDA, D. 



process. In others, the two mouths will be found to be partly 

 divided from one another 

 by new-formed tentacles ; 

 and finally each will have 

 its own circle complete 

 and all else in polyp per- 

 fection. 



Many of the Astr^ea 

 hemispheres of the Paci- 

 fic, grown by this method, 

 have a diameter of ten 

 to fifteen feet. 



In other Astraia-like 

 species, this spontaneous 

 fission ends in a complete 

 separation of the two 

 polyps formed ; and con- 

 sequently in a forking of 

 an old branch. The caulasth^a furcata, d. 



figure annexed, of a Caulastrsea, from the Feejees, illustrates 



