252 



C(ELENTERA TA. 



oesophagus, dividing the peripheral part of the gastral space into 

 small pockets, the radial chambers, connected below the end of 

 the oesophagus with the central part. Above, these chambers con- 

 tinue into the tentacles. The tentacles therefore are outgrowths 

 from the radial chambers and usually are equal in number to them. 

 Besides the complete or primary septa which reach the oesoph- 



FlG. 200. Stereogram of an Anthozoan (orig.). In the cut edges the ectoderm white, 

 the entoderm blocked, the supporting layer black. The septa show the septal 

 muscles, and the communication of the interseptal chambers with the oesophagus 

 is seen. 



agus, there may be others incomplete in that they do not reach 

 the oesophagus and belonging to secondary, tertiary or other series 

 (fig. 203). 



The septa support a number of important organs : the mesen* 

 terial filaments, gonads, and muscles. The mesenterial filaments 

 are thick strands of epithelium rich in glands and nettle cells, 

 fastened like a hem on the edge of the septa. Since they are 

 much longer than the peristomial-pedal length of the septa, they 

 cause these latter to wrinkle and fold, thus strikingly resembling 



