Animals Before Man 



contain the largest existing predatory sharks, 

 those popularly known as "man-eaters," al- 

 though there seems to be some doubt as to 

 their actually attacking man. Some of the 

 pavement-toothed species, however, still existed, 

 those of the genus Ptycliodiis being abundant, 

 and specially noticeable for their massive teeth, 

 most admirably adapted for crushing crabs and 

 shellfish. That these formed their principal 

 food is indicated by the wide, flattened mouth, 

 which shows that these fishes were bottom- 

 feeding creatures. 



Crocodiles and turtles were numerous, and 

 the latter comprised some fresh-water species, 

 and some that were exclusively marine. Among 

 these last was the great sea-turtle, called by 

 Mr. Wieland Archelon (niling turtle), because 

 he was the largest of turtles, either living or 

 fossil. The greatest turtle now in existence is 

 the sea-roving leather-turtle, or sphargis, that 

 never comes ashore save to deposit its eggs and 

 perpetuate its kind. The scientific name of 

 Dermochelys coriacea (leathery-skin turtle) re- 

 lates to the appearance of the animal, and so 



198 



