WHALES. 



375 



spermaceti. The usual length of this gigantic Cetacean is upwards of seventy 

 feet, and its circumference at the largest part fifty-two feet. 



The Whalebone Whales (Balcend] * are provided with heads of enor- 

 mous magnitude in proportion to the size of their bodies, but not much ex- 

 panded in front, and they have no true teeth. Their upper jaw has both its 

 sides furnished with thickly-set plates composed of a peculiar horny substance 

 called " whalebone." These plates are thin and fringed at their margin, form- 

 ing a kind of sieve, that serves to retain the small animals on which these 

 gigantic creatures live. The lower jaw, totally destitute of teeth, lodges a fleshy 

 tongue of stupendous bulk, which, when the mouth is closed, compresses all 



^ 



FIG. 415. WHALEBONE WHALE. 



the interior of the upper jaw and the plates of whalebone suspended from its 

 roof. This structure of the mouth does not allow the whales to live upon 

 animals so large as their size would lead us to suppose. They subsist prin- 

 cipally on small fish, but still more on worms, Mollusks, and Zoophytes, which 

 become entangled in the fringes of their whalebone. The lower jaw is very 

 deep, and shaped somewhat like a vast spoon. When the whale feeds it swims 

 rapidly just under or at the surface, with its mouth wide open. The water, 

 wiih all its contents, rushes into the immense cavity, and filters out at the sides 

 between the plates of the whalebone, which are so close and so finely fringed 

 that every particle of solid matter is retained. 



SECTION III. HERBIVOROUS CETACEA. 



The Herbivorous Cetacea are provided with teeth having flat 

 crowns, a character that indicates their mode of subsistence ; 



* Balcena, a whale. 



