62 CALIFORNIA ACADEMY OF SCIENCES. 



side crossing it and meeting its fellow on the median 

 line just behind the insertion of the fore limbs. The 

 belly is black, dotted and spotted with red. The lower 

 surfaces of the limbs are black spotted with yellowish 

 white and sparsely speckled with red. The tail is either 

 all white or white crossed by wide bands of black.* 



Length to aiu;s 180 210 



Length of tail 198 215 



Snout to orbit 14 19 



Snout to ear 36 45 



Width of head 35 44 



Fore limb 76 87 



Hind limb 102 121 



Base of fifth to end of fourth toe 32 38 



Distribution. — The Chuck-walla or Alderman Lizard 

 inhabits suitable situations throughout the Colorado and 

 Mojave Deserts. It has been taken at Fort Yuma and 

 on the eastern slope of the Julian Mountains in San 

 Diego County, and thence occurs north to the desert 

 ranges in the vicinity of Panamint and Death Valleys, 

 California. It ranges east across southern Nevada 

 (Pahrump Valley) to southwestern Utah. 



Habits. — This lizard, the largest native to California, 

 shares with several others the curious habit of defend- 

 ing itself with its tail. As this organ is very large and 

 muscular, the animal can strike very quick and well- 

 aimed blows, and does so with great vigor when teased. 

 " It was generally found on lava or other dark rocks 

 with which its coloration harmonized. It is a vegetarian, 

 feeding entirely, so far as our observations go, on the 



*There is much variation in the coloration of this lizard, especially as regards the blacli 

 bands of the tail. These may be present or absent in the same individual at different 

 times, and the change seems to be, at least to some extent, directly under the control of 

 the animal. When the specimen whose colors are described above was put in a jar with 

 chloroform, the black bands of the tail disappeared and reappeared several times before 

 the lizard's death. Dr. Stejneger has observed the same color changes and thought them 

 dependent upon the intensity of the light to which the animal is exposed. 



