RULERS OF THE ANCIENT SEAS 65 



that might almost have swallowed the biggest 

 fish of to-day whole, sharks of a size the waters 

 had never before contained, and fortunately do 

 not contain now. We know these monsters 

 mostly by their teeth, for their skeletons were 

 cartilaginous, and this absence of their remains 

 is probably the reason why these creatures are 

 passed by while the adjectives huge, immense, 

 enormous are lavished on the Mosasaurs and 

 Plesiosaurs — animals that the great -toothed 

 shark, Carcharodon megalodon, might well 

 have eaten at a meal. For the gaping jaws 

 of one of these sharks, with its hundreds of 

 gleaming teeth must, at a moderate estimate, 

 have measured not less than six feet across. 



The great White Shark, the man-eater, so 

 often found in story books, so rarely met with 

 in real life, attains a length of thirty feet, and 

 a man just makes him a good, satisfactory 

 lunch. Now a tooth of this shark is an inch 

 and a quarter long, while a tooth of the huge 

 Megalodon is commonly three, often four, and 

 not infrequently five inches long. Applying 

 the rule of three to such a tooth as this would 

 give a shark 120 feet long, bigger than most 



