A Shower of Butterjlies. 69 



On December 6th, Darwin again set sail in the 

 Beagle, after a most successful trip through the 

 country, and carried aboard collections that well 

 represented the fauna of the locality. Being at sea, 

 he found, did not entirely prevent the collection 

 of shore animals. Thus one evening, when ten 

 miles off shore, near the bay of San Bias, the Beagle 

 was fairly surrounded by a shower of butterflies, 

 which extended as far as the eye could reach. 

 Even with a telescope no spot could be discovered 

 free from them, so their numbers can be imagined. 

 The sight was so mar\-ellous that the men remarked 

 that it was snowing butterflies. 



Darwin found it difficult to explain the presence 

 of the insects off shore, as there was no storm or 

 squall which could have driven them out to sea. 



Upon various occasions insects w^ere taken while 

 at sea, some in the nets which were dragged astern. 

 The most remarkable case recorded is of a grass- 

 hopper, which flew aboard the Beagle when she was 

 three hundred and seventy miles from land, off the 

 African coast. Spiders were captured sixty miles 

 from shore, all sailing on little balloons made of their 

 own silk. When they came aboard it was found that 

 they were extremely thirsty, and eagerly drank from 

 drops of water. 



These spiders were, according to Darwin, the 

 aeronauts of the tribe, and he devoted many hours 

 to them. When wishing to rise, the abdomen was 

 elevated and several skeins of silk ejected, which 

 passed up into the air for several yards in the ascend- 

 ing current, and then, releasing its hold, the spider 



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