202 



ACTINOZOA. 



" Glass-plants/' whose siliceous stem may be the 

 product, not of the pol3rpe-mass, but of the sponge 

 on which it is parasitic. 



%• 35- 



ZoANTHAEiA scLEROBASiCA : — Part of a living stem of Anti- 

 pathes anguina, of the natural size. Two pol}^es are shown 

 separately, magnified. 



Of the Madrepores, or Z. Sclerodermata, want 

 of space forbids us to say much. A short sketch 

 of the several families into which the sub-order is 

 divided appears to be the best form into which 

 this part of our subject may be condensed. 



Among the Turbinolidce the corallum is usually 

 simple, never presenting a ccenenchyma. In 

 Coenocyathus continuous lateral gemmation takes 

 place, the corallites so formed remaining con- 

 nected in a close irregular tuft. In Blastotrochus 

 gemmation also occurs, but here it is discon- 

 tinuous. The septa are very perfectly developed, 

 not giving rise to either dissepiments or synap- 

 ticulse {fig. 36 a). 



In the Oculinidce there is a very abundant 

 ccenenchyma, which blends gradually with the 



