I traced as they were exposed in the making of 

 large irrigation ditches. The earth which is dug 

 from these tunnels is ejected from one or more 

 holes, which are closed when the tunnel is com- 

 pleted. Around the entrance holes there is noth- 

 ing to indicate or to publish their presence ; and 

 often they are well concealed. 



These tunnels are from forty to one hundred 

 feet long, run from two to four feet beneath 

 the surface, and have two or more entrances. 

 Here and there is a niche or pocket in the side 

 of the tunnel. These niches are from a few 

 inches to a foot in diameter and in height. In 

 one or more of these the chipmunk sleeps, and 

 in others is stored his winter food-supply. He 

 uses one of these pockets for a time as a sleeping- 

 place, then changes to another. This change 

 may enable the chipmunk to hold parasites in 

 check. The fact that he has a number of sleep- 

 ing-places and also that in summer he frequently 

 changes his bedding, indicates that these efforts 

 in sanitation are essential for avoiding parasites 

 and disease. 



Commonly the bedding is grass, straw, and 

 281 



