ACTINIA. 



Phylum - 



Class 



Sub-Class 



Order 



III.— ACTINIA. 



ccelenterata. 

 scyphozoa. 

 actinozoa. 

 Hexactinia. 



Fig. 54. — Actinia Mesembryanthemum. 



On the left is an expanded individual with viviparous young escaping from mouth. 

 On the right is a partially contracted specimen. 



Actinia mesembryanthemum is a common marine 



organism found between tide marks. It is, at least ex- 



Exte al t^rnally, axo symmetric and cylindrical in shape; 



when expanded it may be about two inches 



long. The base or aboral end is attached to 



a foreign body, such as a rock, and the oral end has a 



ring of numerous short te?itacles surrounding a flat peristome, 



in the centre of which is situated the 7nouth. The exterior 



of the body is smooth and of various shades of brown and 



green, matching its surroundings The body often has 



particles of sand and fragments of shell adhering to it, 



which assist in hiding the animal. On stimulation the 



tentacles are withdrawn into the peristome, and the whole 



animal assumes a rounded and contracted form. So far 



