THE FRESH WATERS 141 



where they are now ? To answer this very 

 reasonable question briefly is not possible, but 

 part of the answer may be given. Among the 

 first animals to have bodies namely, the 

 Sponges we find one family in the fresh waters, 

 and all the rest including many hundreds of 

 different kinds in the sea. That is a straw 

 which shows how the wind blew. Among the 

 Stinging Animals which come next in order 

 the sea-anemones and corals, the jelly-fishes and 

 zoophytes only about half a dozen are found 

 in the fresh waters ; all the rest thousands of 

 different kinds live in the sea. So in many 

 other cases, and the home of the great majority 

 of any great race of animals is likely to be the 

 original home of the race. 



Another step in the argument is the Natural 

 History rule that when an animal has more 

 than one habitat in the course of its life-history, 

 the one in which it starts another generation, or 

 begins its own life, is usually the original home. 



The robber-crab wanders far from the shore 

 and even climbs the hills, but it goes back to 

 the seashore every year to spawn, and there is 

 no doubt at all that it was originally a shore 

 animal. So the fresh-water eel goes to the deep 

 sea to spawn, and there is almost no doubt that 



