64 HYDR.E, JELLYFISIIES, SEA ANEMONES, CORAL POLYI S 



an inch high (Fig. 21). After eighteen months tiiis form 

 begins to increase greatly in length and becomes marked 

 off into many transverse divisions by circular, transverse 

 constrictions so that it resembles a pile of saucers with 



Fig. 22. — Hydralike stage 

 of Aurelia ; saucer forms. 

 After Agaa.siz. 



Fig. 23. — Saucer stage of Aurelia. 



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

 breaks away, swims off, and is known as an ephyra (Fig. 

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

 the adult, umbrella-shaped jellyfish. 



Sea Anemones, C'or.\l Polyps, etc. 



Class in. — Adinozoa (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 hydra, 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 differ in 



