DARWIN. 41 



The Rio Plata was quitted on December 6, 1833, 

 and sail was made for Port Desire, on the coast of 

 Patagonia. One evening, ten miles from the Bay of San 

 Bias, myriads of butterflies filled the air, so that the 

 seamen cried out that it was snowing butterflies. The 

 flight seemed to be voluntary. On another occasion 

 many beetles were found alive and swimming, seventeen 

 miles from the nearest land. But these instances were 

 insignificant compared with the alighting of a large 

 grasshopper on the Beagle, when to windward of the 

 Cape de Verde Islands, and when the nearest land, in a 

 direction not opposed to the prevailing trade wind, was 

 370 miles distant. Marvellous appearances of spiders 

 far from land were also noted. One day when the ship 

 was sixty miles from land vast numbers of a small gossa- 

 mer spider arrived. Its habits in fact were aeronautic ; it 

 would send forth a small thread, and suddenly letting go 

 its hold, would sail .away horizontally. 



The Beagle arrived at Port Desire on December 23, 

 1833, but Patagonia afforded less of interest to the 

 zoologist than the northern countries. The next halt 

 was made at Port St. Julian, no miles further south, on 

 January 9, 1834. Here the evidences of the modern 

 elevation of Patagonia were powerfully reinforced, and 

 further, from the nature of the animal remains arose the 

 conviction that " existing animals have a close relation 

 in form with extinct species," another of the germinal 

 facts which bore fruit in the " Origin of Species." Darwin 

 was led to speculate on the causes which could have 

 extinguished so many great species, and he remarks most 

 suggestively : " One is tempted to believe in such simple. 



