22 EVOLUTION 



a fauna and flora like that of the nearest part 

 of the mainland. 



RESEMBLANCES OF PRESENT FORMS AND 

 PAST ONES. Another seed-impression that 

 was borne in on Darwin's mind during his 

 journeyings was the striking resemblance 

 between the living and the extinct forms in 

 the same area. On his travels into the interior 

 of South America he made large collections, 

 both of living animals and of fossils dug from 

 the red mud of the Pampas, and what im- 

 pressed him most was that the extinct bore a 

 notable correspondence to the extant. No 

 living creatures are more characteristic of the 

 South American fauna than the sloths and 

 ant-eaters; no fossils are more characteristic 

 than the gigantic Megatheriums and Glypto- 

 donts ; and the important fact is the structural 

 resemblance between these creatures of the 

 past and those of the present a structural 

 resemblance which suggested to Darwin that 

 the explanation might be, indeed must be, 

 one of blood-relationship. " This wonderful 

 relationship," he wrote, " in the same conti- 

 nent between the dead and the living will, I 

 do not doubt, hereafter throw more light on 

 the appearance of organic beings on our earth, 

 and their disappearance from it, than any 

 other class of facts." This is, to be sure, a 



