140 



THE SEA SHORE 



body and the stomach, together with the wheel-like arrangement 

 of the mesenteries. At one time all animals that had a radial 

 symmetry the regular arrangement of parts round a common 

 centre were grouped together under the title of Eadiata ; but it 

 has since been recognised that the creatures of this group exhibited 

 such a great diversity of structure that they have been re-classified 

 into two main divisions, one of which constitutes the ccelenterates 

 which we are at present considering, and the other containing such 

 creatures as star fishes and sea urchins. 



FIG. 92. DIAGRAMMATIC TRANS- 

 VERSE SECTION OP AN ANEMONE 



S, stomach : 6c, body-cavity ; m', TO", m'", 

 primary, secondary, and tertiary mesen- 

 teries 



a be 



FIG. 91. STINGING CELLS OF ANE- 

 MONE, HIGHLY MAGNIFIED 



a and r, with thread protruded ; 

 fr, with cell retracted 



FIG. 93. LARVA OF ANEMONE 



On the surface of the mesenteries of the anemone may be seen the 

 ovaries or egg-producing organs. These discharge the ova into the 

 general body-cavity, after which they are ejected through the mouth. 

 The embryos are minute jelly-like creatures that have an active exis- 

 tence, swimming about freely in the ocean by means of vibrating cilia, 

 but after this period of activity they settle down and fix them- 

 selves, gradually assuming the adult form common to the species. 



The habits of sea anemones are particularly interesting, and 



