152 RIO PLATA. [CHAP. vin. 



ticular attention to this subject. The weather had been fine and 

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

 lent 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 maxillee drank 

 eagerly of drops of water; this same circumstance has been ob- 

 served by Strack : may it not be in consequence of the little insect 

 having passed through a dry and rarefied 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 iinaccountable. I thought I could 

 perceive that the spider, before performing the above preparatory 

 steps, connected its legs together with the most delicate threads, 

 but I am not sure whether this observation was 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 Citi- 

 grade (therefore quite different from the gossamer), while standing 



