96 FOUR-FOOTED AMERICANS 



"Do you remember the two great divisions of the 

 animal kingdom or tree, as we call it? " 



" Yes," shouted Rap and Nat, " trunk and branches. 

 The first animal was the trunk that separated it from 

 the vegetable world. Animals without backbones were 

 the lower branches and animals with backbones the top 

 branches." 



" And ^vhat class of animals live on the highest 

 branch ? " 



" ^I — mammals, that give m — milk," said Dodo, so 

 quickly that the others had no time to answer. 



" Because this top Mammal branch is so large, I told 

 you that I would make a tree of it all by itself. Here 

 it is : now you can see how man and his blood brothers 

 'are related." So saying, the Doctor unrolled a long 

 sheet of paper and fastened it to a door, where the 

 firelight shone brightly on it. 



" This tree has several more branches when it grows 

 in warmer countries. You can see where they belong: 

 two very low down by the trunk, and one up near the 

 top where the Monkeys live. This winter you must 

 be content to studj^ the tree as it grows north of the 

 Gulf of jMexico and the Rio Grande, up to the land of 

 snow and the northern lights. Nat, go to the wonder 

 room and bring me the map of North America that 

 hangs there. We will hang it on one side of the 

 animal tree. 



" You see that tlie Rio Grande is the river that 

 bounds the United States on the southwest, and the few 

 branches that are cut from our tree belong to the tropi- 

 cal animals that only stray north of this river by mere 

 accident. 



