116 ANIMAL LIFE IN DESERTS 



What it requires is blown sand which must be at 

 least a foot deep. The probable explanation is that 

 sand is the only soil in which it is able to burrow ; 

 for its incisors are weak, and its claws and feet smaU. 

 In fact, what determines the presence of this rodent 

 in a given spot is the coexistence of two physical 

 factors, loose sand for its burrows, and sufficient 

 depth of sand to accommodate it. 



Associated with the Big Desert Kangaroo Rat, 

 and largely dependent on it for food, one finds the 

 Kit Fox ( Vulpes macrotus arsipus), which is a purely 

 desert animal and apparently occupies the same 

 place in nature in the American sandy deserts as the 

 Fennec Fox in Africa. The Fennec Fox {Vulpes 

 zerda) Uves exclusively in sandy places in the Sahara 

 and Egypt ; it is a small, rather weak fox, which 

 feeds upon beetles, grasshoppers, vegetable matter, 

 and a few small rodents. 



The Marsupial Mole (Notoryctes) of Central Aus- 

 traUa is an inhabitant of sandy places. It possesses 

 the general outward form of our own Mole (Talpa), 

 and of other burrowing mammals, to none of which 

 is it in any way related. It is a cyUndrical animal, 

 with strong shovel-shaped feet, and a reduced tail, 

 and it has no eyes. It makes no definite runs, 

 because the sand collapses at once after its passage, 

 but it spends its time pushing through the sand in 

 search of insects, particularly ants. The Tuco-tuco 

 (Ctenomys), a rodent of South America, exhibits 

 many of the external characters of the mole, though 

 it is related neither to the mole nor to Notoryctes. 

 It is found in isolated colonies wherever sandy 



