126 THE SEA-SIDE AND AQUARIUM. 



of changing their position. They elongate their 

 bodies, and remaining fixed at the base, stretch from 

 side to side as if searching for food at a distance. 

 They can even change their place by gliding upon 

 the disc which supports them; or detaching them- 

 selves entirely and swelling themselves with water, 

 they become nearly of the same specific gravity as 

 the element which they inhabit, and the least agita- 

 tion is sufficient to drive them elsewhere 



When they wish to fix themselves, they expel the 

 water from their distended body, and sinking to the 

 bottom, attach themselves again by the disc at their 

 base, which forms a powerful sucker." 



With all due deference to so respectable an autho- 

 rity, I think the assertion regarding these creatures 

 detaching themselves for the purpose of being thrown 

 or blown about into some new locality, is incorrect. 

 My doubts are due to the following causes": 



1st, That upon no occasion have I ever seen an 

 Actinia so detached, and rolling about in any rock- 

 pool. I have had opportunities, during various sea- 

 sons of the year, of viewing some thousands of these 

 animals; and had such been their usual habit, I am 

 surely justified in expecting that I should have met 

 with at least a solitary instance. 



2dly, I have watched them often, especially the 

 Mesembryanthemum, creeping along the base and upon 

 the sides of the tank, apparently enjoying a pleasant 

 ramble, the body not being at all disturbed. 



And 3dly, I have had specimens of the "Crass" 



