SECT. IT. ANTHOZOA ZOOPHYTES. 119 



SECTION IV. 



ANTHOZOA ZOOPHYTES. 



THE life-history of the oceanic Hydrozoa, which may be 

 regarded as one of the triumphs of microscopic science, 

 would have been incomplete had it been separated from 

 that of the Pulmograde Acalephae and the Physograde 

 groups : but the most important part of that numerous 

 race of animals are the Anthozoa zoophytes, which in- 

 clude the builders of the coral reefs and atolls of the 

 Indian and Chinese seas. The coral polypes, though 

 feeble and inconspicuous individually, when united in 

 large communities acquire a power which enables them 

 to build the most stupendous structures in the midst of 

 a tempestuous ocean. 



The Anthozoa zoophytes, or living flowers, form two 

 extensive groups the Asteroids, or Alcyonian zoophytes, 

 whose polypes have six or eight hollow prehensile ten- 

 tacles radiating round their mouth like a star or the 

 petals of a single blossom, and the Actinian or Helian- 

 thoid zoophytes, which have ten, twelve, or more hollow 

 tentacles encircling their mouth in several rows, like the 

 blossom of a double sun-flower. 



Alcyon Zoophytes. 



The Alcyon zoophytes comprise the Alcyons, Gorgons, 

 and Pennatulidse, or sea-pens. The polypes are of the 

 same form in all, and are united by a fleshy or horny 



