§ 21. THE ACTINIA, OR SEA-ANEMONE. 621 



When alive in the water the Madrepores are invested 

 with a fleshy integument of various colours : and each cell 

 is occupied by a polype, as in the zoophytes previously 

 examined. The appearance of a living Madrepore (31. 

 flantaglneci) with the polypes protruded, is shown in 

 PL VI. Jig. 5, and will serve to convey a faint idea of the 

 beautiful appearance of the live corals in their native 

 element. 



21. The Actinia, or sea -anemone. — In another di- 

 vision of corals the cells are few, and of considerable 

 dimensions, the polypes being of proportionate size, and 

 bearing considerable analogy to the Actinice, or Sea-Ane- 

 mones, which are so common on the rocks, and in the shal- 

 lows on our sea shores ; a few observations on these animals 

 will therefore enable us to comprehend the nature of this 

 group of polyparia. The Actinia, or Sea-animal flower, as 

 it is popularly termed, appears, when quiescent, like a sub- 

 globular mass of tough jelly, of various tints of crimson, 

 green, blue, or brown (see PL VI. Jig. 11); when expanded 

 it presents a broad disk, surrounded by tentacula, having 

 in the centre a corrugated surface, which is contracted into 

 a marsupial or purse-like form. 



The Actiniae are affixed to the rocks by a broad base, but 

 they can detach themselves, and change their position ; on 

 the Sussex coast hundreds may be seen, at low water, in the 

 hollows of the chalk-rocks which are left bare by the reflux 

 of the tide. They are carnivorous and very voracious, 

 feeding on the small fish, Crustacea, and mollusca, that 

 come within their reach. I have kept them for months in 

 sea-water, supplying them daily with meat, which they 

 greedily seized, drew into the sac, or stomach, and after- 

 wards ejected perfectly colourless, having absorbed the 

 juices, and left the tough, muscular fibre. The body of the 

 Actinia is highly contractile and full of cells : the tentacula 

 are hollow tubes, which the animal has the powder of filling 



