ORGANIC EVOLUTION. 57 



of frogs, toads, newts/ and mammals, save only 

 such as are able to fly. 



If space permitted, I might adduce several 

 other highly instructive facts in this argument 

 from geographical distribution ; but I will con- 

 tent myself with mentioning only one other. 

 When Mr. Wallace was at the Malay Archi- 

 pelago, he observed that the quadrupeds 

 inhabiting the various islands belonged to the 

 same or to closely allied species. But he also 

 observed that all the quadrupeds inhabiting 

 the islands lying on one side of an imaginary 

 sinuous line, differed widely from the quadrupeds 

 inhabiting the islands lying on the other side of 

 that line. Now, soundings showed that in exact 

 correspondence with this imaginary sinuous line 

 the sea was much deeper than in any other part 

 of the Archipelago. Consequently, how beautiful 

 is the explanation. We have only to suppose 

 that at some previous time the sea bottom was 



