232 A BOOK-LOVER S HOLIDAYS 



America by another temporary land bridge, 

 but from another continent, South America. 

 These were the ground-sloths, giant edentates, 

 which reached an extraordinary development 

 in the southern half of our hemisphere, where 

 distant and diminutive relatives - - tree-sloths, 

 ant-eaters, armadillos still live. The most 

 plentiful of these California ground-sloths, the 

 mylodon, was about the size of a rhinoceros; 

 an unwieldy, slow-moving creature, feeding on 

 plants, and in appearance utterly unlike any 

 thing now living. 



Together with these great beasts belonging 

 to stocks that in recent geologic time had im 

 migrated hither from the Old World and from 

 the southern half of the New World was an 

 other huge beast of remote native ancestry. 

 This was a giant camel, with a neck almost like 

 that of a giraffe. Camels including llamas - 

 developed in North America. Their evolu 

 tionary history certainly stretched through a 

 period of two or three million - - perhaps four 

 or five million years on this continent, reach 

 ing back to a little Eocene ancestor no bigger 

 than a jack-rabbit. Yet after living and develop 

 ing in the land through these untold ages, over 

 a period inconceivably long to our apprehension, 

 the camels completely died out on this continent 



