ANIMALS— PHYSICAL ENVIRONMENT 75 



is very long, covered with short hairs, and bearing 

 at its tip a large tuft. The short fore-Umbs are 

 used for burrowing, holding food, and apparently 

 also for lifting water to the mouth (page 90) : 

 the length of the hind-limbs is correlated with the 

 habit of progressing by leaping and not by running, 

 and it is possible that they serve also to give the 

 Jerboa and the animals which resemble it an in- 



Fig. 31. Hairy-footed Jerboa {Jaculus jaculus) from Egypt. 



Notice the long hind-legs with reduced number of toes, and the long tail^with a terminal 

 tuft of hair, and the biped attitude. (Draum from life by Miss A. M. Gayton.) 



creased power of observing the approach of enemies 

 on the bare ground. The speed which a Jerboa 

 can attain by jumping, and the great irregularity 

 of its movements, undoubtedly make it extremely 

 difficult to capture, a fact which can be verified if 

 you liberate a Jerboa in the confined space of a 

 room and endeavour to catch it in a butterfly net. 

 The Jerboas (Dipus and Jaculus) belong to the 

 Dipodidse, a family of Rodentia of which all the 



