64 HYDR^, JELLVFISHES, «EA ANEMONES, CORAL POLYl'S 



an inch high (Fig. 21). After eigliteen months this form 

 begins to increase greatl}' in length and becomes marked 

 off hito many trans^•erse di\'isions by circular, trans^'erse 

 constrictions so that it resembles a pile of saucers with 





-tiG. 22. — Hydraiike stage 

 of Aurelia ; saucer forms. 

 After Agassiz. 



Fig. 23. — Saucer stage of Aurelia. 



scalloped edges (Fig. 22). Finally, each division, or saucer, 

 breaks away, swims off, and is kno\Mi as an eph3a-a (Fig. 

 23). The ephyra, witli a few changes, soon develops into 

 the adult, umbrella-shaped jellyfish. 



Sea Anemones, Coral Polyps, etc. 



Class III. — Actinozoa {raylike animals) 



The Actinozoa occur in the sea, in both deep and shallow 

 water, and are often of brilliant hues. They are of the same 

 general structure as the hytlra, but differ in that the mouth 

 opens into a short, distinct gullet, which, in turn, opens be- 

 low into the stomach, or body cavity. They also clifTer m 



