KEPTILES. 



197 



Monkeys use theirs (§ 53). Its movements are slow. 

 No part of it moves quickly but its tongue. This is a 

 singular instrument. It is a long hollow tube with a 

 swollen fleshy extremity, which is always covered with a 

 glutinous substance. In catching insects it is darted out 

 and returned into the mouth with a velocity which al- 

 most eludes the eye, the glutinous secretion making the 

 insect to adhere to the tongue. The eyes of the Chame- 

 leon can be moved independently of each other, which 

 gives the animal a strange aspect, one eye, perhaps, be- 

 ing du-ected forward, while the other is directed back- 

 ward. The skin is covered with horny granulations. 

 The changeableness of the color of the skin has been ex- 

 aggerated ; still, the change is perceptible through vari- 

 ous shades from light to dark, owing to changes in the 

 arrangement of the granules in the skin, and in the amount 

 of blood in them. The lungs are large, and there are air- 

 sacs connected with them in various parts of the body. 

 When these are full of air the animal looks bloated, but 

 the next minute it may appear lean and shrunken, having 

 emptied these sacs. The story that the Chameleon lives 

 on air gained currency partly from this circumstance, 

 and partly from the almost invisible quickness of motion 

 of the tongue, really invisible to the careless observer. 

 The common Chameleon, Fig. 159, abounds in Northern 

 Africa, the south of Spain, and Sicily. 



Fig. 153. — Chameleon. 



