78 ANIMAL LIFE IN DESERTS 



and the assumption of the biped habit. In the 

 deserts of the southern part of North America 

 animals resembling Jerboas have been evolved 

 from yet another family of rodents, the Hetero- 

 myidae. 



The rodents which have already been mentioned 

 all belong to the section Myomorpha ; in another 

 section, the Hystricomorpha, and not closely related 

 to the forms which have been considered, is the 

 Cape Jumping Hare (Pedetes). This animal is 

 much larger than any Jerboa, but resembles that 

 animal in its long hind-legs and long tail : it feeds 

 on all fours, but when it is pursued it escapes by 

 prodigious leaps. It lives in arid and desert places 

 in Africa from Mozambique southwards. 



It is surprising to find similar " Jerboa-like " 

 animals among the totally imrelated marsupials : 

 good examples are Phascogale Hillieri and Ante- 

 chinomys. The last lives in Central Australia in 

 sandy plains among tussocks of grass in the same 

 environment as the rodents Conilurus and Mus 

 gouldi. The Antechinomys and Conilurus are Jer* 

 boa-like, progress by jumping, and show remarkable 

 general similarity in form ; the Mus, which is equally 

 common, and apparently quite as successful in the 

 business of life, is an ordinary mouse, and pro- 

 gresses by running : it is difficult to see why the 

 jumping habit has been evolved in the Conilurus 

 and Antechinomys unless, as Spencer suggests, the 

 resultant irregularity in movement tends to baffle 

 small hawks chasing them. Conilm*us is an ex- 

 tremely abundant rodent ; Antechinomys, which 



