164 



SYSTEMATIC ZOOLOGY. 



tions of each other. Such a compound condition is 

 known as a colony, and the separate members of the 

 colony as hydranths or zooids. Most of the free forms 

 are known as jellyfish or medusce. As a rule a medusa 

 consists of a bell- or umbrella-shaped disc, fig. 13; from 



FIG. 13. Medusa (Melicertum campanula), enlarged. 



the lower surface (corresponding to the handle of the 

 umbrella or the tongue of the bell) projects a proboscis, 

 at the tip of which is the mouth. Around the margin 

 of the bell are the tentacles, and these, compared to the 

 snaky locks of the mythical monster, have given rise 

 to the name. The medusae swim through the water by lazy 

 motions of the umbrellas, feeding upon whatever may 

 come in their way. The medusae are the sexual stage. 

 All of the Coelenterates reproduce by means of eggs, 



