THE AMERICAN NATURALIST 



[Vol. LIII 



tions. They are found more abundantly during the 

 earlier summer months, and during the autumnal rainy 

 season, when the aerial temperature does not exceed 32° 

 C. During these periods the animals move about actively 

 all day, spending the night in protected nooks under 

 vegetation, in the burrows of other animals, or buried 

 beneath the surface of the soil. As the daily maximum 

 temperature becomes greater they are to be found only 

 in the early morning and in the later afternoon when the 

 heat is less intense. During the heated part of the day 

 the lizard is at rest, almost if not quite buried under the 

 superficial layers of the soil. This position is reached in 

 a characteristic manner. The snout is directed down- 

 ward and moved rapidly from side to side, the body ex- 

 tremely flattened, while the legs take part in a rapid hori- 

 zontally clawing movement. The net result of this series 

 of movements is to cover the animal with the loose soil, 

 the depth varying according to the temperature, the char- 

 acter of the soil, and other external conditions, as well as 

 the individual. The same method of burrowing is em- 

 ployed in preparation for hibernation, when the animal 

 may bury itself under several inches of loose soil. In at- 

 tempting to escape from enemies, other lizards have been 

 observed to dig in a similar manner, and it is probable 

 that Phrynosoma also escapes in this way. 



3. Food Relations.— The food consists of various in- 

 sects with which the animals come into contact, ants being 

 more readily eaten by the smaller individuals and beetles 

 (Eleodiini) forming a considerable portion of the diet 

 of the larger ones. No food is taken unless it is living or 

 at least moving. Sand grains set in motion by a heavy 

 wind or otherwise are often snapped up, and sand grains 

 are accordingly found in the feces. 



4. Water Relations.— 'None of the species of Phryno- 

 soma have been observed by the writer to drink water, 

 and it is doul)tful if water, independent of that contained 

 in the insect food, is ever ingested. Many individuals are 

 found in situations where there is never any standing 



