14 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



about avoiding very hot conditions than in seeking warm ones when 

 it was cool. 



Anolis lineatopus may remain active at body temperatures ap- 

 preciably below its preferred body temperatiu^e range. Most lizards 

 studied (Bogert, 1959; Fitch, 1956; Milstead, 1957) become inactive 

 at low temperatures but A. lineatopus do not do so, and I have seen 

 them on cloudy days and around lights at night feeding, fighting, and 

 copulating at environmental temperatures below 25° C when their 

 body temperatures must have been circa ambient. 



In contrast to these observations of activity at low temperatures 

 are those made during the very early morning. Anolis lineatopus left 

 their exposed sleeping sites shortly after dawn but well before sunrise 

 and moved into spots where they were concealed. They moved up 

 onto their usual perches only after sunrise, when they began to bask. 



Studies on other lizards have shown that the preferred body tem- 

 peratm'e is usually not far from the upper lethal temperature and 

 this is probably true in A. lineatopus. On analogy with other lizards 

 one would expect a thermal death point somewhere in the vicinity 

 of 40° C Obviously A. lineatopus cannot occur in places where its 

 temperature would be forced above the thermal death point; it should 

 be noted that on the sunny aqueduct mentioned above (table 3) 

 one of the stones of the aqueduct had a temperature of 41° C. 



The effects of temperatures below the preferred body temperature 

 are almost completely unknown not only in this species but also 

 in most lizards. At very low temperatures, A. lineatopus becomes 

 sluggish and torpid, as the following illustrates. One male cooled 

 in a refrigerator was sluggish when cooled to a body temperature of 

 13° C though still active at 19° C. 



Presumably deleterious effects of moderately low temperature are 

 associated with the slowing of temperature-dependent physiological 

 processes such as heart rate, oxygen consumption, rate of enzymatic 

 action (Bartholomew and Tucker, 1963, 1964; Bartholomew, Tucker, 

 and Lee, 1965; Licht, 1961). 



Hardy (1962) has reported that in Cnemidophorus sexlineatus, at 

 lower temperatures, defecation is delayed and individuals are less 

 eflScient at detecting prey, particularly motionless prey, and take 

 several times longer to dig tunnels. No similar changes were seen 

 in A. lineatopus, but it was noted that A. lineatopus are shyer at 

 lower temperatures and it was suggested that this might be a be- 

 havioral compensation for the slowing of muscle or nerve reaction at 

 lower temperatures (Rand, 1964b). 



Preferred body temperature range may be an important ecologically 

 limiting factor, for this subspecies is absent from dark forest where 



