196 ACTINOZOA. 



Section III. 



CLASSIFICATION OF ACTINOZOA. 



I. Classification. — 2. Order i: Zoantharia. — 3. Order 2: Alcyon- 

 aria. — 4. Order 3 : Kugosa. — 5. Order 4 : Ctenophora. 



1. C]a««<^ifieatioii. — The class Actinozoa may 

 l^e divided into the four orders here defined : 



1 . Zoantharia. — A ctinozoa, in which the tentacles 



are simple or variously modified, in general 

 numerous and, together with the mesenteries, 

 disposed in multiples of five or six. Corallum 

 absent or sclerobasic, in most sclerodermic, 

 the septa of each corallite following the 

 numerical law of the soft parts. 



2. Alcyonaria. — Actinozoa^ in which each pol}^e 



is furnished with eight pinnately fringed 

 tentacles. Mesenteries and somatic chambers 

 in number some multiple of four. Corallum 

 sclerobasic or spicular, rarely thecal, and 

 never presenting traces of septa. 

 Riigosa. — Actinozoaf presentinga sclerodermic 

 corallum, with tabulae and well developed 

 septa arranged in multiples of four. Soft 

 parts unknown. 

 4. Ctenophora. — Transparent, oceanic, delicate 

 gelatinous Actinozoa, swimming by means 

 of ctenophores, or parallel rows of cilia dis- 

 posed in comb-like plates. No corallum. 



2. Order I : Zoantharia. — The chief modi- 

 fications of the plan of structure proper to the 



o* 



