VIII AERONAUT SPIDERS 169 



insect on the wing, with an offshore breeze, would be very apt 

 to be blown out to sea. The most remarkable instance I have 

 known of an insect being caught far from the land, was that of 

 a large grasshopper (Acrydium), which flew on board, when the 

 Beagle was to windward of the Cape de Verd Islands, and when 

 the nearest point of land, not directly opposed to the trade-wind, 

 was Cape Blanco on the coast of Africa, 370 miles distant.^ 



On several occasions, when the Beagle has been within the 

 mouth of the Plata, the rigging has been coated with the web of 

 the Gossamer Spider. One day (November ist, 1832) I paid 

 particular attention to this subject. The weather had been fine 

 and clear, and in the morning the air was full of patches of the 

 flocculent web, as on an autumnal day in England. The ship 

 was sixty miles distant from the land, in the direction of a 

 steady though light breeze. Vast numbers of a small spider, 

 about one-tenth of an inch in length, and of a dusky red colour, 

 were attached to the webs. There must have been, I should 

 suppose, some thousands on the ship. The little spider, when 

 first coming in contact with the rigging, was always seated on a 

 single thread, and not on the flocculent mass. This latter 

 seems merely to be produced by the entanglement of the single 

 threads. The spiders were all of one species, but of both sexes, 

 together with young ones. These latter were distinguished by 

 their smaller size and more dusky colour. I will not give the 

 description of this spider, but merely state that it does not 

 appear to me to be included in any of Latreille's genera. The 

 little aeronaut as soon as it arrived on board was very active, 

 running about, sometimes letting itself fall, and then reascending 

 the same thread ; sometimes employing itself in making a small 

 and very irregular mesh in the corners between the ropes. It 

 could run with facility on the surface of water. When disturbed 

 it lifted up its front legs, in the attitude of attention. On its 

 first arrival it appeared very thirsty, and with exserted maxillae 

 drank eagerly of drops of water ; this same circumstance has 

 been observed by Strack : may it not be in consequence of the 

 little insect having passed through a dry and rarefied atmo- 

 sphere? Its stock of web seemed inexhaustible. While 



* The flies which frequently accompany a ship for some days on its passage 

 from harbour to harbour, wandering from the vessel, are soon lost, and all 

 disappear. 



