THE COLEOPTERA OF MADEIRA 251 



greater specific gravity than beetles for many miles 

 through the air ; and storms and hurricanes are of such 

 frequent occurrence, that they must have played a large 

 part in stocking all uninhabited lands. Again, during 

 great floods, whole forest trees are often carried out to sea, 

 and hundreds of beetles may lurk in the crevices of their 

 bark or even among their foliage, and, under favourable 

 circumstances, be drifted a long way in safety. Even 

 matted rafts covered with soil and bearing living vegetation 

 are occasionally floated out to sea by tropical rivers and 

 may be drifted along for weeks, and ultimately convey 

 scores of insects to far distant lands. A large number of 

 beetles are exceedingly tenacious of life. Immersion in 

 strong spirits for twelve hours will not always kill them, 

 nor will water if much below the boiling point ; so that 

 it is not improbable that some considerable proportion 

 would be found to survive immersion in sea-water for 

 several days. Many facts have not been recorded as to 

 the passage of beetles over wide tracts of ocean, but 

 some of them are sufficiently remarkable. Darwin cap- 

 tured a Colymbetes forty-five miles from land north of the 

 Rio de la Plata; and at seventeen miles off Cape Cor- 

 rientes he caught in a net a number of live beetles of the 

 genera Colymbetes, Hydroporus, Hydrobius, Notaphus, Cy- 

 nucus, Adimonia, and Scarabseus. A Calosoma also flew on 

 board the Beagle when ten miles from the shore of South 

 America, and the Calosoma sycoyhanta is believed occasion- 

 ally to cross the English Channel. Sir Charles Lyell 

 also states that exotic beetles are sometimes thrown on 

 our shores, which revive after being long drenched in salt 

 water. In the case of other insects, we have more positive 

 proof of their passage over wide spaces of ocean. A whole 

 swarm of locusts has been known to pass over Madeira 

 from Africa, a distance of more than 300 miles ; while 

 Darwin himself captured a locust at sea 370 miles from 

 land. Two individuals of the Sphinx atropos flew on board 

 the Hotspur East Indiaman in 1866, during an easterly 

 gale, at a point 260 miles from the coast of Portugal, and 

 were exhibited at a meeting of the Zoological Society. 

 In his work on the Natural History of the Azores, just 



