COMPARISON OF C(ELENTERATES. 309 



COMPARISONS. 



Answer the following questions for sea-anemone and for 

 hydroid : 



(1) Has either a radial arrangement of parts ? 



(2) Are tentacles present ? 



(3) Is there a body-cavity apart from the digestive 

 cavity ? 



(4) How many openings to the digestive tract ? 



