410 THE WORLD OF ANIMAL LIFE 



There is another way, too, in which the earthworm is useful; 

 for, by constantly tunnelling through the earth, it helps to bring 

 air to the roots of the plants, and also promotes the drainage. 



We may thus say that worms are useful in three ways, viz. by 

 renewing the soil, by ventilating it, and by helping to drain it. 

 So they are certainly the allies and assistants of the farmer. 



CCELENTERATA 



As we have seen, the Ccelenterates are radiate in structure like 

 the Echinoderms, but then they are of a distinctly lower organiza- 

 tion. They might be described as the " all-stomach " animals. 

 Many of these creatures are exceedingly beautiful in structure, 

 and in colouring are often magnificent. Some of them, namely, 

 the Corals, produce hard structures of most exquisite designs and 

 texture. Those, however, of which we shall speak, viz. the Jelly- 

 fishes and the Sea-anemones, deposit no such structure whatever. 



JELLY-FISH 



We may have seen upon the sea-shore, when the tide is going 

 down, a number of what seem to be lumps of white or yellow jelly 

 lying motionless upon the sand. Or, as the tide comes in or goes 

 out of some estuary, we may have seen great quantities of the same 

 curious objects floating past, sometimes in such immense numbers 

 that they almost seem to form a solid mass. These are Jelly-fish, 

 and very remarkable creatures they are. 



For their bodies are made up of hardly anything else but sea- 

 water. Yet they are beautiful and often exquisitely coloured, and 

 when the animal is floating in the water with its disc expanded, its 

 delicate tentacles hang down below, and give it the appearance of 

 a wonderful fairy-like mushroom. 



Round the edge of the disc are a number of much more slender 

 threads, which also hang down in the water, and are often so 



