Photograph by Gus A. Swanson 



THEIR LIVING LIES BENEATH THE SNOW 



All nature loves kindness and trusts the gentle hand. Contrast these sheep, ready to fly 

 at the slightest noise, with those in the picture on page 396, peacefully feeding in close 

 proximity to a standing express train. Every one appreciates a good picture of a living 

 animal more than the trophy of a dead one! 



fossil mammals shows conclusively that 

 numberless species have spread from 

 their original homes across land bridges 

 to remote unoccupied regions, where thev 

 have become isolated as the bridges dis- 

 appeared beneath the waves of the sea. 



VAST NATURAL MUSEUMS OF ENTINCT 

 ANIMAL LIFE 



For ages Asia appears to have served 

 as a vast and fecund nursery for new 



mammals from which Xorth Temperate 

 and Arctic America have been supplied. 

 The last and comparatively recent land 

 bridge, across which came the ancestors 

 of our moose, elk, caribou, prong-horned 

 antelope, mountain goats, mountain sheep, 

 musk-oxen, bears, and many other mam- 

 mals, was in the far Northwest, where 

 Bering Straits now form a shallow chan- 

 nel only 28 miles wide separating Siberia 

 from Alaska. 



39S 



