221 



walls of the coral now in course of formation (Fig. 77 C, c) 

 forming a groundwork or pedestal on which the actinula rests. 

 D represents the young polype rig. 77. 



resting on the limestone pedestal. 

 In the experience of Lacaze-Du- 



W Actinia into twelve small folds forming the bases of 

 ;| the partitions within. 



i The tentacles next arise, being the elongation of 



A the chambers between the partitions, six larger and 

 J elevated, six smaller and depressed (Fig. 77, D). 

 i The definitive form of the coral polype is now as- 

 sumed, and in the Astraeoides it becomes a compound 

 polypary. 



The singular floating young Edwardsia, originally 

 xchnactis, has been 

 Haicam a ai found ^ Mr - ^" Agsissiz to be the early swimming 

 a ""da? a stage of Edwardsia, a worm-like Actinian, which, 

 like Halcampa albida (Fig. 78 1 ), lives in the sand or mud, unat- 

 tached to any fixed object. 



Kowalevsky has lately found that the Cerianthus, a gigantic 

 Actinia which lives in a tube in the mud at great depths, has a 

 free swimming early stage like Edwardsia. 



The following is a summary of the changes undergone by the 

 polypes so far as known 



1. Egg fertilized by true spermatozoa. 

 2 ? Morula. 



