DARWIN AND WALLACE 29 
madillo. One evening, seated alone in the broad 
expanse of the pampas, the idea suddenly swept over 
him, stimulated, of course, by his study of Lyell: 
“Can it be that the little armadillo and the sloth of 
to-day are the degenerate descendants of the enormous 
megatherium and glyptodon of the past?” But his 
mind was not yet ready to accept so bold an idea and 
he swept it aside. 
The people of this wild neighborhood interested 
Darwin very greatly, and he describes them with care. 
In this connection a charming trait of Darwin’s char- 
acter comes beautifully in evidence. The absolute 
purity of his mind, his utter freedom from grossness, 
shows clearly in his account of the first really semi- 
civilized people he had ever seen. 
A little later, while exploring Patagonia, Darwin 
noticed the terrace-like formation of that desolate 
country. A flat near the sea was succeeded by a 
rapid rise, then came another flat. Three of these 
terraces in succession stretch back toward the An- 
des. At the base of the high terraces Darwin found 
marine shells, largely similar to those of the ocean 
beach so many miles to the east. His study of Lyell 
led him to suspect at once that this portion of South 
America had been raised in successive stages out of 
the bed of the Pacific. When they passed around 
Cape Horn and up the western coast he hunted for 
