(56 A.\OLIUS. 



The genus Anolius exhibits another curious arrangement in its loose skin under 

 the throat, generally folded, but capable of great distention at will, when it forms 

 a dewlap of brilliant colours. 



Most naturalists have supposed that this dilatation was produced by inflation, or 

 the passage of air into the sac or fold, and hence has this been given generally as 

 one of the generic characters. 



Mr. Bell, a celebrated herpetologist of London, was the first, I believe, who 

 observed the real cause of this distention of the skin at times under the throat, 

 and demonstrated that it was not by inflation or filling the fold of skin with air, 

 as there is no communication with the dewlap and the trachea, fauces or mouth, 

 by which air could enter. The fold of skin is drawn do^^'n by a peculiar arrange- 

 ment of the lingual bone, and a singular elastic cartilage fixed to it and attached 

 to the skin. These parts are moved by delicate muscles, so that when the carti- 

 lage is drawn do-rni, the skin of course is distended, and follows it in "the same 

 way that the silk is stretched over the whalebone of an umbrella."* 



In fact, the skin, when distended in life by the animal, docs not resemble the 

 inflated vocal sacs of the toad or frog, which are round, but looks like a fold of 

 the skin, pinched and drawn down, the two portions being in contact, like a true 

 dewlap.t 



* Zool. Jour., vol. ii. p. 11. f Vide anatomical portion of this work. 



