290 PALEONTOLOGY. 



reptiles are preserved in the new red-sandstone of Scotland, 

 England, Germany and America. " 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 

 of their course. Not a track remains of a single loot, 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 surface of our 

 infant planet, have left memorials of their passage, enduring 

 and indelible. 



" No history has recorded their creation or destruction ; 

 their very bones are found no more among the fossil relics of 

 a former world. Centuries and thousands of years may 

 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 are 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." * 



Eirst Order. CHELONIA. Have the ribs transformed into 

 a carapace, and the sternum into a plastron, to form an osseous 

 case for containing the organs of circulation, respiration, and 

 digestion. The extremities are constructed for a terrestrial 

 or an aquatic life, and the carapace and plastron present 

 modifications which characterise the terrestrial, palustrine, 

 and marine families. 



1st Family. The TESTUDIN^, or land tortoises, are cha- 

 racterised by the height and solidity of the carapace, which is 

 covered with a variable number of non-imbricated scales. 

 The parts which correspond to the vertebraB have five plates ; 

 there are four on each side covering the ribs, and twenty- 

 three disposed around the border, 5 + 8 4-23=36. The toes 

 are short, united to their extremities, and are adapted for 



* Dr. Buckiand's Bridgcwater Treatise, p. 263. 



