136 On Mastodontoid and Megathertoid Animals. 



community of character, differ from each other in each divi- 

 sion — and in that later formation, where a very few only of 

 the same types are visible, they are linked on to a new class 

 of beings, the first created of those Saurians, whose existence 

 is prolonged throughout the whole Secondary period ; whilst 

 we have this year seen reason to admit, that even birds (some 

 of them of gigantic size) may have been the cotemporaries of 

 the first great lizards. With the close of the Palaeozoic sera 

 we have also observed a gradual change in the plants of the 

 older lands, and that the rank and tropical vegetation of the 

 Carboniferous epoch is succeeded by a peculiar flora. In the 

 next, or Triassic period, we have another flora, whilst new 

 forms of fishes and mollusks indicate an approach to that pe- 

 riod when the seas were tenanted by Belemnites and Am- 

 monites, marking so broadly these secondary deposits with 

 which British geologists have long been familiar, and which, 

 commencing with the Lias, terminate with the Chalk. And 

 lastly, from the dawn of existing races, we ascend through 

 successive deposits gradually becoming more analogous to those 

 of the present day, until at length we reach the bottoms of 

 oceans so recently desiccated, that their shelly remains are un- 

 distinguishable from those now associated with Man, the last 

 created in this long chain of animal life in which scarcely a 

 link is wanting! — all bespeaking a perfection and grandeur of 

 design, in contemplating which we are lost in admiration of 

 creative power. 



Such results, grand as they are — nothing less in short than 

 the records of creation — are, however, but a portion of the 

 labours of geologists. They have also struggled to explain 

 the causes of those great revolutions. In some continents, it 

 is true, the pages in the book of Nature are, as it were, unruf- 

 fled ; for, by whatever agency effected, it is certain that beds 

 of vast ancient oceans have been so equably elevated and de- 

 pressed, and again so steadily elevated from beneath the sea, 

 that the continuity of their rocky desposits over areas larger 

 than our kindoms of Western Europe is unbroken, and their 

 original condition almost entirely preserved. In other regions, 

 on the contrary, the sediments in the sea and the masses of 



