Vol. IX] VON GELDERN— FLORIDA CHAMELEON 327 



the throat-fan in Anolis is independent of the swallowing of 

 air, or any great ventral excursion of the basi-hyal. The 

 hyoid apparatus in Anolis forms a lever of the first class while 

 in Colotes, although not so stated by Chemin, it forms a lever 

 of the second class. What Chemin calls the fulcrum, namely 

 the basi-hyal, is not a fulcrum since this is the point where 

 force is employed. The true fulcrum lies somewhere along 

 the processus entoglossus. 



CONCLUSIONS 



1. The throat- fan of the Anolis carolinensis is distended 

 when the animal is apparently undisturbed. It is also dis- 

 tended during various emotional states interpreted as anger, 

 fear or sex impulses. 



2. The throat-fan is produced by the hyoid apparatus. It 

 is accomplished by the tapering processus retrobasalis, which 

 'swings vertrad and cephalad carrying a fold of skin before it. 

 Since the distal portion of the retrobasalis is more flexible 

 than the proximal portion, the semi-circular outline of the fan 

 is produced. The thinness of the fan is due to the cohesion 

 of the moist opposing surfaces of the fold of skin and to 

 atmospheric pressure. 



3. The hyoid apparatus may be compared to a lever in 

 which the first part of the anterior horn acts as the power 

 arm, the basi-hyal as the fulcrum and the processus retro- 

 basalis as the long arm. The anterior and posterior horns act 

 as lateral supports and when acted upon by the muscles, fix 

 the fulcrum. 



4. The power is produced by the cerato-hyoids, which exert 

 force in a caudal direction and draws the short arm of the 

 lever dorsad and caudad, which in turn causes the weight arm 

 to move cephalad and ventrad. The fulcrum is fixed by the 

 antagonistic action of the supra- and infra-hyoid group of 

 muscles. 



BIBLIOGRAPHY 



Bronn, H. G. Klassen und Ordnungen des Thier-Reichs. II. 

 Eidechsen und Wasserechsen. 



