160 RIO PLATA [chap, viil 



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

 though light breeze. Vast numbers of a small spider, about one- 

 tentli 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 con- 

 sequence of the little insect having passed through a dry and rare- 

 fied atmosphere? Its stock of web seemed inexhaustible. While 

 watching some that were suspended by a single thread, I several 

 times observed that the slightest breath of air bore them away 

 out of sight, in a horizontal line. On another occasion (25th) 

 under similar circumstances, I repeatedly observed the same kind 

 of small spider, either when placed or having crawled on some 

 little eminence, elevate its abdomen, send forth a thread, and then 

 sail away horizontally, but with a rapidity which was quite un- 

 accountable. I thought I could perceive that the spider, before 

 performing the above preparatory steps, connected its legs toge- 

 ther with the most delicate threads, but I am not sure whether 

 this observation m as correct. 



One day, at St. Fe, I had a better opportunity of observing 

 some similar facts. A spider which was about three-tenths of 

 an inch in length, and which in its general appearance resembled 

 a Citigrade (therefore quite different from the gossamer), while 

 standing on the summit of a post, darted forth four or five threads 



