418 THE WHALE. 



under the immense pressure to which it is sometimes 

 exposed, to exclude the sea-water from its lungs. 

 This pressure, under some depths to which the 

 whale is known to descend, is upwards of a ton upon 

 every square inch; yet, so far from the water being 

 forced down the spiracles, the enormous load serves 

 only more effectually to press down, and close the 

 valves that defend the passages to the lungs. 



The whale has no external ear, and the opening 

 of the passage to this organ is so small as not to be 

 easily discovered. In the sucking whale, it was 

 only one-sixth of an inch in diameter. An elegant 

 contrivance appears in the meatus auditorius exter- 

 nusfor protecting the ear against pressure from with- 

 out. It consists of a little plug, like the end of the 

 finger, inserted into a corresponding cavity, in the 

 midst of the canal, by a slight motion of which the 

 opening can either be effectually shut for the exclu- 

 sion of the sea-water, or opened for the admission 

 of sound. 



In the sucking whale, the skull or crown bone 

 was six feet in length, from the anterior extremity 

 to the condyles. In a full grown animal, in which 

 the whalebone was ten feet four inches, the length 

 of the skull, measured along the upper and convex 

 side of the curve, was twenty feet eight inches, the 

 cavity on the crown of the same, occupied by the 

 muscular valve of the blow-holes, was 14 inches 

 wide, and &4? inches long. 



