Aquatic Mammals 243 



down motion and not from side to side 

 in the manner adopted by the majority 

 of fishes. Almost the entire motive 

 power is supplied by the tail, the flippers 

 though huge enough being generally small 

 in proportion and serviceable merely for 

 turning. A ten-foot whale probably de- 

 scribes a circle of nearly 100 feet in order 

 to reach its starting point. This in- 

 ability to turn may in some measure 

 account for the immense distances 

 covered by schools of whales. Fish, 

 having struck a good feeding ground, can 

 turn and turn again until the food supply 

 is exhausted. A whale, on the other 

 hand, forges blindly forward and having 

 taken what it can of such food as crosses 

 its path must plod ahead until another 

 chance of a passing snack offers itself. 



Porpoises are merely whales in minia- 

 ture. The oil they yield is not sufficient 

 to tempt the money-maker, whilst their 

 hide is as thin as notepaper, and cannot 



