Beyond the Horizon 259 



in the finders and toes, In the whales these numbers 

 Invariably are exceeded. In some instances the fingers 

 have more than twenty joints, a feature greatly re- 

 sembling the many-jointed flipper of the extinct Ich- 

 thyosaurus and allied prehistoric marine lizards. The 

 flippers, usually small though sometimes of considerable 

 length, are not used to propel the animal in swimming, 

 seeming to be more for the purpose of maintaining its 

 equilibrium or keeping it on an even keel. It swims by 

 the sculling action of the flukes of its great tail which 

 is not placed vertically as In fishes, but horizontally. 

 This position is better adapted to the requirements of 

 the animal which must needs often seek the surface for 

 air to breathe. 



Cetaceans, although having many features in com- 

 mon by which they are easily identified from other 

 mammals, nevertheless differ considerably from one 

 another. As I have alreaciy observed, one of these 

 differences is in respect to size. Some, the smaller dol- 

 phins, are less than a yard long; the other extreme is 

 found in the blue whale, or rorqual, which is said to 

 be nearly ninety feet in length. But there Is a more 

 fundamental difference than that of mere size; and it 

 is one which has caused them to be divided into the two 

 great groups that naturalists now refer them. These 

 are the whalebone whales, or the Mystacoceti, and the 

 toothed whales, or Odontocett. 



Even the members of each of these groups exhibit 

 enough differences to make further divisions possible 

 The whalebone whales are split into two families which 

 in turn are subdivided into genera and species. In one 

 family are included the so-called "right whales," and 



