ADAPTATIONS TO TROPICS AND ALTITUDES 



Figure 19. Distortion of the daily cycle of the use of fixed time points (03, 07 

 11, 15, 19 and 23 hr.). 



40 



HOUR OF DAY 



Figure 20. Comparison of daily temperature cycles in new world monkeys; 1, 

 Cebus ; 2, Ateles ; 3, Aotus ; 4 , Callithrix ; 5 , Cebuella . Broken curve for the nocturnal 

 Aotus has been shifted twelve hours to allow comparison to diurnal forms. 



407 



