V. 



SUBKINGDOM CCELENTERATA. 



General Characteristics. — The CcBlenterates (hollow- 

 entrailed) are radiates having a distinct body-cavity, whose 

 walls consist of an outer layer {ectoderm) and an inner layer 

 (endoderm). They are all aquatic, and multiply alike by 

 budding, by eggs and by fission. They are usually armed 

 with peculiar stinging filaments. 



CCELENTERATA, 



Digestive catitt, with two openings. Ctenophora, 



Digestive cavitt, double, with radiating spaces. Anthozoa. 



DiGBSTivB CAviTr, SINGLE. Hydrozoa. 



CLASS I. CTENOPHORA. 



General Characteristics. — The Cteno- 

 phora (comb-bearers) are transparent, ge- 

 latinous bodies, with eight rows of comb- 

 like fringes and two long tentacles provided 

 with lateral filaments spirally coiled. The 

 latter can be instantly withdrawn into the 

 cavities from which they spring, and as 

 quickly shot forth again. The Ctenophora 

 have a nervous system and complex diges- 

 tive apparatus. 



Fig. m. 



PleurobracJaa jnlius, 



A Ctenophore. 



o, a. Tentaculce ; 



b. Mouth. 



CLASS II. ANTHOZOA. 



General Characteristics. — The Anthozoans (flower-like 

 animals) or Polyps (many-f. ^tc ^"^ comprii " the Ccslenterates 

 in which a distinct digestive sac opens oelow into the general 

 cavity of the body, though separated from the body-walls by 

 an intervening space. The mouth is surrounded by one or 

 more rows of hollow tentacles, which are covered with cilia 

 in constant motion, to produce currents for bringing food, 

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