208 



ANIMAL STUDIES 



probably the same is true of the crocodiles and alligators 

 and some of the larger snakes. Their enemies are few, and 

 death usually results when the natural course is run. 



Throughout life all reptiles periodically shed their skin, 

 as birds do their feathers and mammals their fur. In the 

 snakes and some of the lizards the skin at the lips loosens, 

 and the animal gradually slips out of its old slough, bright 

 and glossy in the new one which previously developed. In 

 the others the old skin hangs on in tatters, gradually com- 

 ing away as they scamper through the grass. 



FIG. 121. Head of the lizard, or "horned toad" (Phrynosoma blanivillei), showing 

 the translucent pearly scale covering the pineal eye. From nature, by W. S. 

 ATKINSON. 



