SOME REMARKABLE TYPES 



49 



or " paddles/' while the tail has developed a pair of fleshy cc flukes " 

 (Fig. 14), which are placed in a horizontal plane, thereby differing 

 from the tail of fishes, which is vertical. And the reason for this 

 is not difficult to trace. Fishes breathe the oxygen suspended in 

 the water, and consequently do not need to come periodically 

 to the surface for air ; and thus it is that the tail of the fish is 

 contrived to drive the body straight forwards. The whale, on 

 the other hand, must breathe atmospheric air ; accordingly the 

 " flukes " of the tail are horizontal in position, thereby driving 

 the body up to the surface for air, and down into the depths 

 for food. 



While the porpoises and some whales have the jaws armed 



FIG. 14. The Greenland whale, showing how the body originally supported on 

 four legs has become transformed by the adoption of an aquatic life. The 

 small dot behind the eye is the aperture of the ear. 



with teeth, some whales have supplanted the teeth which still 

 appear in the unborn young by long, horny, fringed plates, the 

 so-called whalebone. These plates, set closely together, have 

 their inner edge fringed, whereby they act as strainers. For 

 these whales feed upon small molluscs and other marine 

 organisms which swarm in the seas frequented by these 

 leviathans. When feeding, the whale suddenly opens its 

 mouth, which is immediately filled by the inrush of water and 

 the organisms floating therein. When the mouth is closed, the 

 tongue, which is fleshy and of great size, is forced up towards 

 the roof of the mouth, and, as a consequence, drives out the 

 water between the plates of " whalebone " or " baleen," as it 



VOL. I. 4 



