12. SCELOPORUS 337 



upon the highest branches or in the nests of the wood rats 

 which are constructed of the detached branches of these 

 shrubs on the ground beneath. If the bushes are approached 

 at a good pace the chances are that no lizards will be seen, 

 for when frightened they scramble swiftly down the stems 

 and into a hole, if there is time, or if not, flatten themselves 

 out against the trunk of the shrub or among the dead 

 branches on the ground. In such cases they do not give them- 

 selves away by the teetering movement so characteristic of 

 many lizards, and their extraordinary resemblance to the 

 trunk or a lobe of an Opuntia makes them very difficult to 

 discern. Many times I have seen an individual scuttle down 

 the trunk of one of these cacti but on carefully approaching 

 the bush would be unable to distinguish it, although it would 

 be in full view. Only the great development of the scales 

 in these lizards would protect them from the needlelike 

 spines of the Opuntias, and permit of their moving about 

 upon them with such facility. 



"In regard to its food habits Dr. Merriam remarks that 

 in the Great Basin region 'Sceloporus magister is a mixed 

 feeder, both insects and flowers being found in the stomachs 

 examined. At the Great Bend of the Colorado, Nevada, 

 and St. George, Utah, stomachs were opened that contained 

 insects only.' The stomach contents of the Tucson speci- 

 mens consist almost entirely of insects. A small amount of 

 vegetable matter is present in some of them, but this is in 

 the form of small, dried fragments that were probably taken 

 up with the animal food. Ants make up the great bulk of 

 the contents of these stomachs, and every one examined 

 contained great numbers of these insects. A few beetles 

 are also present, but they make up a very small proportion 

 of the total contents. The stomach of one lizard that was 

 taken under a Crucifixon thorn bush was distended with 

 scores of winged ants. 



