44 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



two of the courtships; in these, just before the male seized her neck, 

 the female moved her head from side to side. 



There may be an inviting or receptive display on the part of the 

 female but I was unable to recognize it. Certainly the females do not 

 bob to indicate their receptivity as Evans has recorded for female A. 

 carolinensis. 



Copulations were observed from August 24 to May 30. They seem 

 to occur throughout the year. 



The above description of a copulation mentions that the male 

 copulated with a female that was resident in his area even though 

 there was an adult female closer to him and tethered so that she could 

 not escape. On another occasion, a different male approached about 

 10 feet, apparently in response to my placing a female stake-out in 

 his home range. When he reached the vicmity of the stake-out and 

 had inspected her, he mated with a free female that was nearby and 

 with which I had seen him before. I tried tethering females within 

 the home ranges of males on several other occasions and in no case 

 did a male attempt to mate with them. 



These observations suggest the possibility that the males recognize 

 the females that live within their home ranges as individuals. The 

 observations can also be explained by saying that a female tied up is 

 not a suitable mate or that the tethered females were not receptive 

 while the free-living ones were and that the male could detect this. 



There are two other data relevant here. One is that adult male 

 and adult female home ranges overlap intersexually more frequently 

 than one would expect on chance (p. 33). Apparently adults of one 

 sex or the other, and perhaps both, prefer to live in a home range 

 which overlaps that of an adult of the other sex. 



The final piece of evidence is the very simple and almost casual 

 way in which copulation occurs and the small amount of display that 

 immediately precedes it. A great deal of display is given by the 

 males in the presence of the females to which the females do not react 

 overtly. If it has any effect on them at all, it must be a cumulative 

 effect over a period of time. This is possible since all of the copula- 

 tions that I observed involving marked lizards took place within the 

 normal home ranges of the lizards mvolved. The cumulative effect 

 of the display may result in keeping the female aware of the male's 

 presence, in bringing her into sexual receptivity (as in many birds), 

 or in reducing her fear of or aggression toward him. The studies 

 of Hunsacker (1962), showing that there are two displays in Scelop- 

 orus, one which attracts the females to stay near the male and another 

 which is precopulatory, suggest that the cumulative effect of display 

 postulated for A. lineatopus may occur widely in iguanids. 



