ANIMALS— PHYSICAL ENVIRONMENT 99 



malus), a vegetarian lizard of the Calif ornian deserts 

 which sits upon rocks when they are too hot for 

 the hand to touch (Camp). 



Many insects have the same power of Hving on 

 the surface of the soil at midday, even during the 

 hottest season. On June 2, 1922, I observed at 

 Jericho, Palestine, at noon that the shade tem- 

 perature was 90° F. (32-3° C), and the surface of 

 the hard clay soil 124° F. (50-8° C), and on it two 

 species of mantis larvae (Eremiaphila and Fischeria), 

 and adults of a Short-horned Grasshopper, were 

 moving about. In deserts nearer the Equator 

 much greater surface temperatures (page 21) are 

 attained, but these figures serve to show the degree 

 of heat to which the insects, etc., are exposed on 

 the bare desert. 



The case of the diurnal mammaha of the desert 

 is very different, and their survival of summer 

 midday conditions is not so remarkable. Such 

 animals as hares, gazelles, and camels are large, so 

 that in any case they would not be exposed to 

 very rapid fluctuations of internal temperature : 

 they are, moreover, warm-blooded, that is to say, 

 provided with a mechanism which maintains their 

 bodies at or near a constant temperature : there- 

 fore fluctuation of air temperature affects a gazelle 

 or camel, or even a hare, very much less than it 

 affects a Hzard or beetle; so that the power of 

 j the mammals to survive the midday heat is less 

 i remarkable than their ability to provide themselves 

 I with water, by the evaporation of some of which 

 ! they maintain their "normal temperature." 



