30 EXTINCT MONSTERS 



some of the most ancient of rocks, such as those of the Cambrian 

 system, jelly-fish have left indelible impressions of their soft 

 round bodies ! 



Speaking of the wonderfully enduring nature of certain im- 

 pressions known to geologists, the sagacious Dean Buckland said, 

 in an address to the Geological Society : " The historian or the 

 antiquary may have traversed the fields of ancient or of modern 

 battles, and may have pursued the line of march of triumphant 

 conquerors, whose armies trampled down the most mighty 

 kingdoms of the world. The winds and storms have utterly 

 obliterated the ephemeral impressions in their course. Not a 

 track remains of a single foot or a single hoof of all the countless 

 millions of men and beasts whose progress spread desolation over 

 the earth. But the reptiles that crawled upon the half-finished l 

 surface of our infant planet have left memorials of their passage, 

 enduring and indelible. Centuries and thousands of years have 

 rolled away, between the time in which these footsteps were 

 impressed by tortoises upon the sands of their native Scotland 

 and the hour when they were again laid bare and exposed to our 

 curious and admiring eyes. Yet we behold them stamped upon 

 the rock, distinct as the track of the passing animal upon the 

 recent snow ; as if to show that thousands of years are but as 

 nothing amidst eternity, and, as it were, in mockery of the fleeting 

 perishable course of the mightiest potentates among mankind." 2 



Every form of animal life that, writhing, crawling, walking, 

 running, hopping, or leaping, could leave a track, depression, or 

 footprint behind it, might thereby leave similar lasting evidence 

 of its existence and also, to some extent, of its nature. The 



1 This expression is a survival from the teaching in vogue fifty years ago. 

 The world was not in an unfinished state during the period of the New Eed 

 Sandstone. 



2 Bridgewater Treatise, vol. i. p. 251. 



