352 Darwin and Geology 



In a letter to Henslow in 1834 Darwin says : " I have just got 

 scent of some fossil bones... what they may be I do not know, but if 

 gold or galloping will get them they shall be mine\" 



Darwin also showed his sense of the importance of the discovery 

 of these bones by his solicitude about their safe arrival and custody. 

 From the Falkland Isles (March, 1834), he writes to Henslow : "I have 

 been alarmed by your expression 'cleaning all the bones' as I am 

 afraid the printed numbers will be lost : the reason I am so anxious 

 they should not be, is, that a part were found in a gravel with recent 

 shells, but others in a very different bed. Now with these latter 

 there were bones of an Agouti, a genus of animals, I believe, peculiar 

 to America, and it would be curious to prove that some one of the 

 genus co-existed with the Megatherium : such and many other points 

 depend on the numbers being carefully preserved^" In the abstract 

 of the notes read to the Geological Society in 1835, we read: "In 

 the gravel of Patagonia he (Darwin) also found many bones of the 

 Megatherium and of five or six other species of quadrupeds, among 

 which he has detected the bones of a species of Agouti. He also met 

 with several examples of the polygonal plates, etc.^." 



Darwin's own recollections entirely bear out the conclusion that 

 he fully recognised, while in South America, the wonderful signi- 

 ficance of the resemblances between the extinct and recent mammalian 

 faunas. He wrote in his Autohiography. "During the voyage of 

 the Beagle I had been deeply impressed by discovering in the Pampean 

 formation great fossil animals covered with armour like that on the 

 existing armadillos*." 



The impression made on Darwin's mind by the discovery of these 

 fossil bones, was doubtless deepened as, in his progress southward 

 from Brazil to Patagonia, he found similar species of Edentate 

 animals everywhere replacing one another among the living forms, 

 while, whenever fossils occurred, they also were seen to belong to the 

 same remarkable group of animals^ 



1 M. L. I. p. 15. 



2 Extracts from Letters etc., pp. 13 — 14. 



3 Proc. Geol. Soc. Vol. ii. pp. 211—212, * L. L. i. p. 82. 



* While Darwin was making these observations in South America, a similar 

 generalisation to that at which he arrived was being reached, quite independently and 

 almost simultaneously, with respect to the fossil and recent mammals of Australia. In 

 the year 1831, Clift gave to Jameson a list of bones occurring in the caves and breccias of 

 Australia, and in publishing this list the latter referred to the fact that the forms belonged 

 to marsupials, similar to those of the existing Australian fauna. But he also stated that, 

 as a skull had been identified (doubtless erroneously) as having belonged to a hippo- 

 potamus, other mammals than marsupials must have spread over the island in late 

 Tertiary times. It is not necessary to point out that this paper was quite unknown 

 to Darwin while in South America. Lyell first noticed it in the third edition of his 

 Principles, which was published in May, 1831 (see Edinh. New Phil. Journ. Vol. x. [1S31J, 



