THE POLYPS AND COnAL-MAKEm 



37 



rounded with one or more circles of tentacles* We thus 

 come in our ascent up the scale of animal lift! to creatures 



■mr 



with a single, definite stomach or digestive sac, opening 

 outward by a definite mouth. 



* See the works of Darwin on Coral Reefs, Dana's Corals and 

 Coral Islands, A. Agassiz's Seaside Studies in Natural History, 1871. 



