218 THE SPECIAL SENSES. 



;. 



91. In those animals whose hearing is more delicate 

 than that of man, the corresponding organ is of greater 

 importance, it being larger and supplied with muscles of 

 greater power, so that it serves as a natural kind of ear- 

 trumpet, which is easily movable in the direction of any 

 sonnd^that attracts the attention of the animal. Bold, 

 predaceous animals generally have the concavity of this 



FIG. 53. THE EAR AND ITS DIFFERENT PARTS. 



A. Diagram of the Ear. 



a, b. External Ear. d. Middle Ear. 



c, Membrane tympani. e. Internal Ear. 



B to B"'. Bones of the Middle Ear (magnified). 

 C, The Labyrinth?, or Internal Ear (highly magnified). 



organ directed forward, while in timorous animals, like the 

 rabbit, it is directed backward. Fishes have no outer ear, 

 but sounds are transmitted directly through the solid bones 

 of the head, to the internal organ of hearing. 



92. The auditory canal (Fig. 53, A, b), which is con- 

 tinuous with the outer opening of the ear, is a blind pas- 

 sage, an inch and a quarter in length, its inner extremity 

 being bounded by a closely-fitting, circular membrane. 

 This canal is of oval form, is directed forward and inward, 



91. The car in the animate of delicate hearing! Kabbit? Fishes? 



92. What is the auditory canal ? Describe it. 



