62 DENIZENS OF THE DESERT 



— and the same may be said of the pocket rats 

 and a number of other small mammals of the 

 desert regions — is their ability to live on 

 almost indefinitely without drinking water or 

 eating moist food of any kind. They are thus 

 unusually well adapted to live in arid places. 

 This ability to subsist without water is the 

 more amazing to us when we consider the 

 large amounts necessary to sustain other higher 

 animal life in the same region. Lieutenant Gail- 

 lard, of the Mexican Boundary Survey, gives 

 the average amount of water consumed on 

 the desert during the summer by each man 

 of the Survey to be about seven quarts a day 

 and twenty gallons for the pack animals. The 

 desert animals subsisting without water must 

 elaborate all the moisture for their bodies from 

 the food they eat, much of which, especially 

 in summer, is of an extremely dry character, 

 mostly diy seeds. Most of the species of pocket 

 mice are found in the arid Southwest, and none 

 occur east of the Mississippi River. They are 

 very sensitive to cold and moisture and thrive 

 best where the rainfall is least. 

 The spiny pocket mice are so called because 



