166 



palseontology was beginning to reveal, and never 

 deigned to doubt that tbe future would be otherwise 

 than the present. Even still there are certain minds 

 who ignore aU that geology has taught concerning 

 the extinction of old races and introduction of newer 

 ones, and who, shutting their eyes to the continuity 

 of nature, cannot perceive that the same course of 

 extinction and creation must ever be in progress. 



Nor is it any valid argument in support of an 

 opposite view that the animals depicted on the monu- 

 ments of Egypt are the same now as they were three 

 thousand years ago, and that if a law of variation 

 had been in operation, some perceptible change ought 

 to have been observable in such a lengthened period. 

 Setting aside the briefness of the time as compared 

 with the aeons of geology, and the character of the 

 depictments upon which no zoologist could found 

 minute specific distinctions, the great fact remains, 

 that the animals are mainly local, and that the valley 

 of the Nile has undergone little or no physical change 

 for ages — those changes of external conditions, 

 which, if not the sole cause, are at least most inti- 

 mately connected with variations in vegetable and 

 animal existences. Change the conditions : let 

 Northern Africa gradually sink, and the sea roll, as 

 it once rolled, over the Sahara and Libyan desert; 

 and three thousand years hence say what might be 



