314 CALIFORNIA ACADEMY OF SCIENCES [Pkoc. 4th See, 



It is evident that in distending the fan, the folds flatten out 

 and the closely approximating scales become more or less 

 separated, showing the pink or vermilion epidermis between 

 them. 



The fan is distended frequently and during various emo- 

 tional states. It is a common observation to see one of the 

 lizards sitting on a branch or fence rail, suddenly rise up on 

 its front legs, distend the fan and accompany this by a quick 

 succession of up-and-down motions produced by flexing and 

 extending the front legs. No purpose for the act is apparent 

 since the animal is undisturbed by outside influences. 



A male Anolis will, upon spying a female, bob up and down 

 and distend his fan with great frequency as if he were dis- 

 playing himself to his greatest advantage. 



Two males in combat will keep their fans distended, rise up 

 on their toes, flatten out their bodies from side to side, and 

 erect a fold of skin along the midline of the back of the neck. 

 The usual appearance of the animal is thus markedly changed, 

 even the prominent eyes, with their visible yellow irises, 

 recede and appear as black beads. With grotesque, lateral 

 swaying motions the combatants slowly encircle one another, 

 each awaiting an opportunity to make a final rush and end 

 the struggle victoriously. When one of these lizards is cap- 

 tured and held in the hand it will attempt to bite in a most 

 vicious manner and distend the fan at the same time. 



II 



The underlying mechanism in the production of the fan is 

 the hyoid apparatus, as has been stated by Ditmars, Gadow, 

 Chemin, Bronn and others. None of these authors except 

 Chemin has, as far as I have been able to ascertain, described 

 the mechanism and the forces employed. 



For the purposes of description the hyoid apparatus of 

 Anolis may be divided into a basi-hyal ; anterior extension or 

 processus entoglossus; third horn of Chemin, posterior horn 

 of Huxley or the processus retrobasalis ; anterior horns, lesser 

 horns or cerato-hyals and the posterior horns, middle horns 

 of Huxley, greater horns, cerato-branchials or thyro-hyals. 

 (Fig. 1 A.) 



