APPENDIX. 221 



PLATE V. 



COEALS AND SeA AnEMONES. 



Caeyophyll^la. Smithil ply. fig. 2. Fl YL fig. S. 



The connexion between Brainstones, Mushroom 

 Corals, and other Madrepores abounding on Poly- 

 nesian reefs, and the " Sea Anemones," which have 

 lately become so familiar to us all, can be seen by 

 comparing our comparatively insignificant C. Smithii 

 with our commonest species of Actinia and Sagartia. 

 The former is a beautiful object when the fleshy part 

 and tentacles are wholly or partially expanded. like 

 Actinia, it has a membranous covering, a simple sac- 

 like stomach, a central mouth, a disk surrounded by 

 contractile and adhesive tentacles. Unlike Actinia^ 

 it is fixed to submarine bodies, to which it is glued 

 in very early life, and cannot change its place. Un- 

 like Actinia, its body is supported by a stony skeleton 

 of calcareous plates arranged edgewise so as to ra- 

 diate from the centre. But as we find some MoUuscs 



