THE BIGGEST BEAST 91 



through an unlimited supply of luscious food. The size 

 of terrestrial animals is also, it appears, definitely related 

 to the natural water-supply. There are very few small 

 quadrupeds in the interior of Africa. On account of 

 frequent " drought," the mammals have often to run a 

 hundred miles or more in search of water. Only animals 

 as big as the larger antelopes and the zebra can cover the 

 ground. The smaller kinds die (and have, in fact, died 

 out in past ages) in these regions of sudden drought. 



The gigantic reptile Diplodocus on land. 



