SOME OTHER LITTLE SEA-CREATURES. 153 



other forms of these plant-like hydroids. Some 

 you may find growing on old shells, looking like 

 little, stiff, brown grasses an inch or two in height. 

 Others are quite long and slender, like threads, 

 and they have numerous branches. 



But the test for them all 

 is the microscope, which 

 need not be more than a 

 pocket-lens. All of the 

 true hydroids have little 

 cups on their sides, look- 

 ing sometimes like fine 

 saw-teeth. And if you get 

 a live specimen and put it 

 in a dish of sea-water, you 

 may be able to see the little 

 polyps unfold their pretty 

 arms, like the opening of a 

 flower. But they are very 

 shy, and at the least fright 

 they draw back into their 

 sheltering home. 



There are very queer 

 stories told us about these 

 hydroids by men who have 

 carefully studied their life- 

 history. They seem to be Figure 84. 



