14 BRANCH CCELENTEKATA. 



Campanularian. Finally, all the saucers thus swim away 

 and, rapidly growing, become Jelly-fish.* 



CLASS ACTINOZOA (ak ti no zo'a). 



Some of the members of this class are remarkably 

 like the Hydra ; a circle of tentacles, disposed radially 

 around the mouth, being supported upon a cylindrical 

 body. 



ACTINOZOA, 'however, are exclusively salt-water ani- 

 mals ; are of comparatively large size ; and have the 

 mouth not opening directly into the body-cavity, but 

 leading through an oesophagus (e sofa gus) into a bag-like 

 stomach, which is open below and allows the nutritive 

 products of digestion to pass into the body cavity. The 

 oesophagus and stomach, moreover, are held in position 

 by a radial series of fleshy partitions, the mesenterial 

 folds, attached at their peripheries (pe rif'er iz) to the 

 body wall. This body wall, though tough, is soft and 

 flexible, and can be expanded with sea-water, which the 

 animal, on being irritated, allows to escape through lateral 

 pores and from the mouth, thus contracting itself to a 

 mere knob. Often the body wall, as in previous forms, 

 supports buds which in turn may support other buds, 

 giving rise to branching forms. In such cases, the skin 

 may be stiffened by the deposition of horny matter, or 

 of lime, making a stem either tough and flexible, or 

 hard and brittle. 



* Jelly-fish abound along the coast, and are to be seen by the thousands in 

 cairn weather during the summer months, appearing at night like specters mov- 

 ing about with their phosphorescent light. Though many are small, the size of 

 a cup, others are as large as a tub, and their long streamers, armed with lasso- 

 cells, cause no little annoyance to bathers. The bodies of Jelly-fish are loosely 

 held together, and on being removed from the water, will often slip through the 

 hand in strings. So much of the body is water, that, if allowed to remain in the 

 sun's rays, after desiccation little more than a mere scale will be left. 



