PHYLUM C(ELENTERATA 



141 



Subclass II. Zoantharia. — Anthozoa with usually many 

 simple hollow tentacles, arranged generally in multiples of five 

 or six; two siphonoglyphes as a rule; mesenteries vary in num- 

 ber, the retractor muscles never arranged as in the Alcyonaria; 

 skeleton absent or present; simple or colonial; dimorphism rare. 



Order 1. Edwardsiidea. — A few shallow water Zoantharia 

 with eight complete mesenteries and from fourteen to twenty 

 or more tentacles. 



Order 2. Actiniaria. — Zoantharia usually solitary ; many 

 complete mesenteries; no skeleton. Examples: Metridium 

 (Fig. 84), Halcampa, Bunodes. 



These are the sea-anemones. Some of them are parasitic; 

 Bicidium is parasitic on the jellyfish Cyanea. Many sea- 

 anemones are beautifully colored; in the large Stoichactis of the 

 Great Barrier Reef of Australia, " the spheroidal bead-like 

 tentacles occur in irregularly mixed patches of gray, white, 

 lilac, and emerald green, the disk being shaded with tints of gray, 

 while the oral orifice is bordered with bright yellow." (Kent.) 



Order 3. Madreporaria. — Zoantharia usually colonial; 

 many complete mesenteries; calcareous skeleton formed by 



Fig. go. — Oculina 

 speciosa, a branch of 

 madreporarian coral. 

 (From Sedgwick, 

 after Ed. H.) 



Fig. gi. — Meandrina, a rose-coral of the 

 order Madreporaria. (From Weyssc.) 



