THE DESERT HORNED LIZARD 275 



color blend with the gravel and sand that it is 

 almost impossible to see him when he is quiet. 

 Time after time when walking on the dunes I 

 have almost stepped upon horned lizards, and 

 would have crushed them under foot had they 

 not shambled off and through their motion 

 apprised me of their presence. 



A detailed examination of the body brings to 

 light several other peculiar adaptations to a life 

 on the sands. 



In many individuals the ear drum is almost 

 wholly concealed by a scaly membrane, a 

 peculiarity found only among desert species. 

 The ear is often further protected by folds in 

 the scaly skin of the short neck. Just beneath 

 the outer horny skin covering are numerous 

 pigment cells, each with its yellow pigment 

 granule or chromatophore. These highly de- 

 veloped color bodies are under the direct con- 

 trol of the nervous system and the animal is 

 able to make color adjustments with a fair 

 rapidity, so that if its wanderings carry it onto 

 darker or lighter soils it is capable of bringing 

 about a color coat suitable to its environment. 



Mr. Leonhard Stejneger, who made the report 



