48 CHARLES DARWIN 



ing that Darwin was already familiar with Lamarck's 

 writings, and as pointing out the natural course of his 

 own future development. 



For the two years from her arrival at Monte Video, 

 the ' Beagle ' was employed in surveying the eastern 

 coast of South America ; and Darwin enjoyed unusual 

 opportunities for studying the geology, the zoology, and 

 the botany of the surrounding districts during all 

 that period. It was a sugge'stive field indeed for the 

 young naturalist. The curious relationship of the 

 gigantic fossil armour-plated animals to the existing 

 armadillo, of the huge megatherium to the modern 

 sloths, and of the colossal ant-eaters to their degenerate 

 descendants at the present day, formed one of the direct 

 inciting causes to the special study which produced at 

 last the 'Origin of Species.' In the Introduction to 

 that immortal work Darwin wrote, some twenty-seven 

 years later, ' When on board H.M.S. " Beagle " as natu- 

 ralist, I was much struck with certain .facts in the dis- 

 tribution of the organic beings inhabiting South Ame- 

 rica, and in the geological relations of the present to the 

 past inhabitants of that continent. These facts, as will 

 be seen in the latter chapters of this volume, seemed to 

 throw some light on the origin of species that mystery 

 of mysteries, as it has been called by one of our greatest 

 philosophers.' And in the body of the work itself he 

 refers over and over again to numberless observations 

 made by himself during this period of rapid psycho- 

 logical development observations on the absence of 

 recent geological formations along the lately upheaved 

 South American coast ; on the strange extinction of the 

 horse in La Plata ; on the affinities of the extinct and 



