TONGUES OF REPTILES. 129 



The tongue of the frog is of great length ; its 

 root is attached close to the fore part of the 

 lower jaw, while its point, which is cloven, is 

 turned backwards, extending into the throat, and 

 acting like a valve in closing the air passage 

 into the lungs. If, when this animal has ap- 

 proached within a certain distance of the insect 

 it is about to seize, we watch it with attention, 

 we are surprised to observe the insect suddenly 

 disappear, without our being able to perceive 

 what has become of it. This arises from the 

 frog having darted out its tongue upon its victim 

 with such extreme quickness, and withdrawn it, 

 with the insect adhering to it, so rapidly, that it 

 is scarcely possible for the eye to follow it in its 

 motion. The Chameleo7i also has a very long and 

 slender tongue, the extremity of which is dilated 

 into a kind of club, or spoon, and covered with a 

 glutinous matter : with this instrument the animal 

 catches insects at a considerable distance, by a 

 similar manoeuvre to that practised by the frog. * 



As Serpents swallow their prey entire, so the 

 bones of their jaws and face are formed to admit 

 of great expansion, and freedom of motion upon 

 one another. Serpents and Lizards have gene- 

 rally curved or conical teeth, calculated rather 



* Mr. Houston has given a descriptipn of the structure of this 

 organ, and of the muscles by which it is moved, in a paper con-^ 

 tained in the Transactions of the Royal Irish Academy, vol. xv. 

 p. 177. ; . . i ;-/ '. 



VOL. II. . K 



