52 THE OCEAN RIVER 



flipper to flipper. Still more fearsome creatures, the plesiosaurs 

 and mosasaurs, the giant sea serpents of their day, ploughed 

 through the seas with long necks stretched before them, up to 

 40 feet in total length. There have been many legends and 

 some creditable observations of giant serpentlike creatures in 

 modern seas, but they are usually dismissed as an optical illu- 

 sion, as a deliberate hoax, or as giant squids, fishes, or porpoises, 

 honestly mistaken for the sea serpent. Anthonie Cornelis 

 Oudemans, in his critical treatise on the great sea serpent, sug- 

 gests that there may actually be hidden in the oceans today an 

 enormous long-necked sea lion, v^hich has given rise to the 

 hundreds of detailed accounts. The possibility that giant ple- 

 siosaurs may still be lurking in the depths of the ocean is not 

 seriously considered, but it cannot fail to give rise to specula- 

 tion when taken in conjunction with the coelacanth fish, 

 hitherto thought to have died out in the same period as these 

 serpent-like monsters but now known to live in the twentieth- 

 century ocean. 



When the age of reptiles came to an end the present age of 

 fishes took its place in the salt seas; and only a few crocodiles, 

 turtles, and small sea snakes now survive to remind us of their 

 former splendor. But the main tread of evolution still con- 

 tinued, and the mammals which inherited the mastery of the 

 land gave rise in turn to oflPshoots which found their way back 

 to the parent ocean. Seacows which, in spite of their uncouth 

 faces, may have originated the mermaid myth; whales, the 

 largest living sea creatures today, and their relatives, the por- 

 poises, first swam the seas after the Ocean River had drawn 

 back from the rising land movement which gave birth to the 

 Rockies, Andes, and Himalayas. This was in the Eocene, only 

 30 million years ago. They were followed about 10 million 

 years later, around the time the Alps were formed, by Miocene 

 sea otters, seals, and sea lions, the seagoing cousins of the 

 carnivorous cats, dogs, and bears. 



There are smaller movements going on today between the 



