EVIDENCES OF EVOLUTION 21 



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 inte- 

 rior of South America he made large collec- 

 tions, both of living animals and of fossils 

 dug from the red mud of the Pampas, and 

 what impressed him most was that the ex- 

 tinct bore a notable correspondence to the 

 extant. No living creatures are more char- 

 acteristic of the South American fauna than 

 the sloths and ant-eaters; no fossils are more 

 characteristic than the gigantic Megathe- 

 riums and Glyptodonts; 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 relation- 

 ship," he wrote, ;< in the same continent 

 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.' 3 This is, to be sure, 

 a cautious statement; but it seems not un- 

 likely that it was while thus digging his 



