LESSON XXVIII. 

 THE EAR. 



A. SKATE. 



1. Cut through with a strong sharp scalpel or with 

 bone forceps the cartilaginous roof of the skull 

 transversely between the eyes; remove the 

 posterior part of the roof. Opposite the hinder 

 part of the brain the cartilage will be seen to be 

 much thicker than elsewhere; it contains the 

 vestibule and semicircular canals : slice it away 

 till one of the semicircular canals is reached; 

 when this is done, trace it, removing the upper 

 portion with a scalpel or a strong pair of scissors. 

 Note 



a. The almost transparent membranous canal 

 much smaller than the cartilaginous canal 

 in which it lies. 



b. The ampulla or spindle-shaped dilatation of 

 the membranous canal close to one end. 



c. The opening of the semicircular canal at 

 either end into a large membranous bag, 

 the utriculus. 



19-2 



