OF SEA-ANEMONES. 15 



tenanted b}" a little creature of most beautiful form 

 and most active habits. All polyps are not thus clus- 

 tered, but many are, and the distinctive characters of 

 the class are the facts of their heing fixed, either soli- 

 tarily or in masses, by a stem, and their possessing 

 arms (tentacles, e. g.), with which they seize their 

 food. 



Other classes of Kadiates are — 



2. AcalejyJis, or " stinging animals," as " sea blub- 

 bers" or jelly fish, which swim freely in the waters 

 by the alternate contraction and expansion of their 

 body. 



3. Echinodenns, or "prickly- skinned" animals, as 

 "star-fish," "sea-urchins" and the like, also moving 

 freely in the waters : with these we are not concerned, 

 for our sea-anemone is a "polyp " or "true zoophj^te," 

 being an animal which is general^ fixed to the rock 

 which he chooses as a dwelling-place. 



I must inflict one more series of divisions upon 

 the student, before we can get a proper answer to 

 our question. 



These "pol3''ps" are of three kinds: — 



1. Hydraforms. Each polyp is solitary or joined 

 to a stem common to a great many individuals; and 

 the stem or " polyp-house," as it is called, is horny, 

 and hollowed like a reed. Example, Hydra, Sertu- 

 laria, &c. [hydraform means "hydra-like."] 



2. Asteroids. The polyps are united in families 

 like those of the last division, but the " polyp-house " 



c 2 



