THE FRESH WATERS 141 



to be 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 hun- 

 dreds 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 



