ANTHOZOA. 59 



individuals as have taken up their residence on the half-submerged 

 rocks, where the daily recess of the tide exposes them to observa- 

 tion, are covered with rough warts, and blotched with dusky brown, 

 and dull orange ; and still further to insure their concealment, cover 

 themselves with fragments of shells, seaweed, and gravel, which 

 adhere to their skin so strongly as not to be washed oif ; and being 

 thus veiled, the animals are quite concealed from observation. On 

 the other hand, those species which inhabit deep water, as if aware 

 that the necessity for concealment no longer existed, use. no such 

 precaution : their skins are smooth and naked, and adorned with 

 the vivid tints which make the species so beautiful. These Actinise 

 are easily procured, and may be kept alive in sea water for a long 

 time without difficulty : in a glass vessel their beauty is displayed to 

 advantage. They are capable of very long fasts, although suffi- 

 ciently voracious when food is to be obtained. 



Although the Actiniae are usually fixed to the 

 bottom by their broadly-expanded bases, many of 

 them can detach themselves, and float through the 

 water to a new resting-place ; or they will slide along 

 slowly over the rocks, by the action of their base or 

 foot, and some are said to turn themselves over and 

 walk upon the extremities of their tentacles. There 

 is, indeed, a small group of Actiniae (Actineta) fitted 

 expressly for an ocean life, by means of an air-cavity 

 in the base containing a vesicular or spongy disk 

 made up of air-cells, which serves as a float. Thus 

 provided, the animal lies on the water with its base 

 uppermost and its mouth and tentacles below the 

 surface, and in this position it is carried about by 

 winds and currents. 



The tentacles of the Actiniae are not always 

 simple tubes: in the A. aleyonoides, represented on 

 the left hand of our engraving (Fig. 41, i), they are of 

 a very complex character, and are provided near 

 their tips and at their sides with minute suckers, 

 with which they are enabled to grasp their pr.ey. 



In common with the Hydrozoa the Actiniae are 

 furnished with an armature of oblong, transparent 

 vesicles, which have the power of shooting out a long 

 thread-like lasso of excessive tenuity. These abound 

 on the tentacles ; but there are also certain special 

 organs upon which they are crowded to an extra- 

 ordinary degree, and which seem to be simply 



