Comparative investigations are being conducted in this Laboratory of the evolutionary and neural roots of species-typical, communicative behavior. It is the working hypothesis that an ancient part of the forebrain known as the paleostriatum plays a basic role in such behavior. In connection with work on reptiles, a behavioral inventory (ethogram) of the lizard Anolis carolinensis has been made for evaluating changes in behavior in experiments involving the paleostriatum and other parts of the forebrain. Special attention has been given to characterizing different features of the so-called (1) signature, (2) aggressive, and (3) courtship displays. The analysis has uncovered 26 discrete behavior patterns that may be associated with these displays.