unmodified air, about 30°. These temperatures varied 

 somewhat in the various experiments, as shown by the 

 records, but were fairly constant throughout a single 

 experimental period. 



The records of Experiments 34a and 346 show, for 

 Phrynosoma modestum, that the optimum air tempera- 

 ture is in the neighborhood of 35° or 36°. The graphic 

 records of Experiments 86 and 88 (PI. I) show similar 

 results. It will be noticed in the record of the former 



