NATURAL THEOLOGY. 71 



Fig. 10. 



a, the external ear, called the concha, or trumpet. 10, hols 

 of the ear, slit open ; termed the meatus auditorius externus, 

 or outward passage of the ear. 9, membrane of the tym- 

 panum, stretching across the ear; or the main drum head of 

 the ear. It makes a complete partition at the bottom of the 

 hole of the ear. 1, 2, 3, 4, lines pointing to the four little 

 bones seen extending across the tympanum or drum, behind 

 the membrane of the tympanum, the last of the bones being 

 in the shape of a stirrup : and the lower end of the first bone 

 being inserted into the membrane of the tympanum. 6, en- 

 trance into the labyrinth, or back drum of the ear, having 

 a membrane over it on which the stirrup plays. 5, three 

 lines pointing to the semicircular canals, which form a part 

 of the labyrinth. 7, the cochlea or shell, so named from its 

 resemblance to a cockle, and forming a portion of the laby- 

 rinth. 8, the Eustachian tube, leading from the tympanum 

 or drum to the back part of the mouth. - 



you know extends across and shuts up the passage, a 

 little within the entrance ? 



A. Though there is no communication in this di- 

 rection, there is another passage, called the Eusta- 



