XII 



IGUANIDAE 



535 



the broiling sun, heating themselves well through ; and in the 

 afternoon, long before sunset, when the sand is warmed up to 

 40 C., or fever-heat, they prepare to go to bed. For this they 

 select a dry and soft spot, and within a few minutes manage to 

 dig themselves in flat, literally sinking into the sand by pushing 

 themselves forwards, and by shovelling the sand upon their 

 backs with peculiar motions of the fringed sides of their flat 

 bodies. Sometimes the spines of the head remain sticking out, 

 looking like dry thorns scattered over the sand. To prevent the 





FIG. 134. Phrynosoma coronatum ("Horned Toad"). x 1. 



latter from getting into the nostrils, these are provided with 

 closely- fitting valves. Thus they remain concealed during the 

 night, and not until the sun is well up do they leave their 

 hiding-place, first peeping out, and then raising their head and neck, 

 letting the sand roll off between the spines. Still half con- 

 cealed, the back covered with little pebbles, seeds, or bits of dry 

 leaves, they wait for a long time before they feel lively enough 

 to sally forth. Although mostly slow and deliberate in their 

 movements, stalking about with arched back, and raised upon 

 the fore-limbs, they can run fast enough for a few yards before 

 they stop again and nod in a ridiculous way. When they 

 see themselves observed, they shut their eyes and slowly sink 



