194 SKETCHES OF CREATION. 



ive phases of animal life have swept like waves over the 

 surface of our planet, but none has been more striking or 

 more real than that which was dominant through Mesozoic 

 time. Throughout the whole extent of Great Britain there 

 has not been known a single large reptile during the human 

 era ; yet in the single era of the Wealden the British do- 

 minions maintained four or five species of Dinosaurs fifteen 

 to twenty feet in length, ten or twelve Crocodilians, Lacer 

 tians, and Enaliosaurs ten to fifty or sixty feet in length, 

 besides Pterosaurs and Turtles, to say nothing of the prob 

 ably numerous species whose fossil remains have as yet es- 

 caped observation. These successive swells in the stream 

 of animal life are convenient stand-points from which to 

 note the progressive development of organic existence. 

 The history of reptiles, like that of fishes, presents some 

 remarkable exceptional features, which have a most im- 

 portant bearing upon the question of " development," 

 which is taking a front rank among the questions of the 

 age. But these aspects of the case are reserved for future 

 consideration. 



