RADIATES. 341 



derives its name from the lily-like form which some of its 

 species present. Most of the species are extinct, but they 

 are found in their fossil state abundantly in limestone 

 and some other rocks. The other aberrant order is that 

 in which are those animals that are called by sailors Sea 

 Cucumbers, from their resemblance in form and in sur 

 face to the cucumber of our gardens. 



594. The second class of the Radiata is that of the 

 Acalephs. These animals are called Sea Nettles and 

 Stangfishes, from the stinging sensation which nearly all 

 of them can inflict on being touched. They are also call- 

 ed Jelly-fishes, from their great softness. Most of their 

 bulk is merely water. Though one may weigh even 

 many pounds when first taken from the water, when it 

 has lost all its fluid parts it will weigh only as many 

 grains. There are many species, some being no larger 

 than the head of a pin, and some being of very consider. 

 able size. 



595. One of the most common of these animals is the 

 Medusa. This is often seen in great multitudes floating 

 along near the shore in a calm, bright day. You see the 

 shape and usual position of the animal in Fig. 268, B. 



Fig. 268. 



Its body is umbrella -shaped, with a fringe around its 

 edge. It is by a waving motion of this umbrella that it 

 moves along in the water. Its mouth is in the centre of 

 the under surface, and from around it hang down fouf 

 leaf-like tentacula, which are both feelers and graspers 



