Dec. 1833. aeronaut spiders. 189 



land, attached in vast numbers to the lines, proves that they 

 are the manufacturers of the mesh, and that the habit of sail- 

 ing through the air, is probably as characteristic of some tribe, 

 as that of diving is of the Argyroneta. We may then reject 

 Latreille's supposition, that the gossamer owes its origin to 

 the webs of the young of several genera, as Epeira or Thomisa : 

 although, as we have seen that the young of other spiders do 

 possess the power of performing aerial voyages.* 



During our different passages south of the Plata, I often 

 towed astern a net made of bunting, and thus caught many 

 curious animals. The structure of the Beroe (a kind of jelly 

 fish) is most extraordinary, with its rows of vibratory ciUae, 

 and comphcated though irregular system of circulation. Of 

 Crustacea, there were many strange and undescribed genera. 

 One, which in some respects is allied to the Notopods (or 

 those crabs which have their posterior legs placed almost 

 on their backs, for the purpose of adhering to the under 

 side of ledges), is very remarkable from the structure of its 

 hind pair of legs. The penultimate joint, instead of being 

 terminated by a simple claw, ends in three bristle-like 

 appendages of dissimilar lengths, — the longest equalling that 

 of the entire leg. These claws are very thin, and are serrated 

 with teeth of an excessive fineness, which are directed 

 towards the base. The curved extremities are flattened, and 



* I was not at the time aware of M. Virey's very curious observations, 

 (Bulletin des Sciences Natur., torn, xix., p. 130) which seem to prove that 

 small spiders, in an atmosphere perfectly tranquil, and without the aid of 

 any web, have the power of darting through the air. M. Virey, believes 

 that by means of a rapid vibration of their feet, they walk the air. 

 Although in his case, the conclusion seems almost inevitable, yet in the 

 one I have described, we must suppose that the several threads which were 

 sent forth, served as sails for the atmospheric currents to act on. After 

 reading M. Virey's account, it appears to me far from improbable, that 

 the little aeronaut actually did unite, as was suspected, its feet together 

 by some fine lines ; thus forming artificial wings. I regret I did not de- 

 termine this point with accuracy ; for it would be a curious fact, that a 

 spider should thus be able to take flight by the aid of temporary wings. 



