No. 624] BEACTIONS OF PIIRYNOSOMA 



47 



optimum. The graphic records of Experiments 10 ar 

 28 (PI. I) show similar results. 



EACTiONS OF Phrynoso 



IE OF THE SUBSTEATUM 



mployed in Table I. 



ndicated by the ( 



umerals burrowed in the space 



The individuals of Plirynosoma douglassii gave prac- 

 tically the same figures for the optimum substratum 

 temperature. The graphic records of Experiments 101 

 and 26 indicate the behavior of this animal in the gradient. 

 Statistical records of the behavior of Phrynosoma doug- 

 lassii and Plirynosoma cornutum in this gradient were 

 not made, because of the size of the animals, Avhich pre- 

 vented the introduction of any number into the cage at 

 the same time. 



Phnjnosoma cormitum, as illustrated by the records 

 of Experiments 45 and 66 (PI. I), chose a higher sub- 

 stratum temperature than either of the other species, 

 averaging nearly five degrees above that shown by the 

 other curves. 



