WONDERS FROM NATURE'S BOOK 235 



low tide to get theii' food from among the seaweed, 

 or to catch some of the smaller fish. Of com-se we do 

 not know just why they walked about upon the shore, 

 but we know that they did walk there, for they, too, 

 left their footprints. They went lumbering along, 

 some of them w^alking on four feet, some of them 

 walking on two with a pair of shorter forelegs to rest 

 on, and dragging long tails after them, much as a 

 kangaroo does. They left their tracks upon the sand 

 and mud they walked on, and these were preserved 

 so that we see them many, many years afterwards. 



Many of their bones have been found, too, and 

 so we have been able to picture to ourselves how 

 these monstrous creatures looked. It was when 

 they ventured out too far upon the soft mud that 

 they were caught in it, for how could they pull 

 their huge feet out from the soft, sticky mass? 

 Then the mud hardened into rock, and their bones 

 were preserved. Whole skeletons have been found 

 and set up in museums, so we have these, as well 

 as the footprints^in the rocks, to tell us what huge 

 creatures lived upon the earth when it was still 

 young. 



Not only those great footprints but even the tiny 

 tracks of insects are perfectly preserved in the rocks 

 that were once mud. There were many insects then, 

 grasshoppers, dragon flies, beetles and spiders. Some 

 of them walked along on the fine, damp mud and left 

 their tracks and often they, too, were caught where 

 the mud was too soft. Their feet were small enough, 

 but they had so many that while they were pulling 

 out a pair of feet all the others would be hopelessly 



