146 



ZOOLOGY. 



prehensile tails; amongst reptiles, the chameleon offers the 

 same peculiarity. 



OF THE VOICE. 



296. In certain of the lower animals there exist- no 

 trace of this faculty ; in insects, the sound produced by the 

 friction of their wings, or of some other tegument HI -y parts, 

 is a necessary result of their movements, as of Hight, for 

 example, and can scarcely be viewed as a phenomenon of 

 expression. But in the higher animals the voice acquires 

 another importance: it is under the direction of the will ; it 

 is more varied, and depends on a totally different cause ; for 

 in all these, it is caused by the passage of the air in a deter- 

 minate point of the respiratory canal, disposed in such a way 

 as to cause the air to vibrate. 



297. The larynx (Pig. 23), surmounting the trachea 



Fig. 92. -Skeleton of the Vulture.* 



* The different bones are indicated by the same letters as in the preceding 

 figures. 



