CHAP. IV. FLOATING WEBS OF SPIDERS. 123 



rous insects (Hydrometra StagnorumFah., fig.4<2.) sport 

 also on the surface, much in the manner of the Gyrinus. 



(146.) In the apterous class of insects, none are 

 more remarkable than the spiders : they can walk, like 

 flies, against gravity, but by what particular means 

 appears uncertain. They are expert climbers, ascend- 

 ing and descending by means of a secretion of which 

 they can make use at pleasure, and which they form 

 into a silky thread, up arid down which they travel at 

 will. But the most singular of all their movements is 

 that which they accomplish by means of those gossamer 

 webs, which, on a bright summer's day, we sometimes 

 see floating and sparkling in the sunbeams. These, 

 for a long time, excited the curiosity and stimulated 

 the conjectures of naturalists ; but they are now ascer- 

 tained to contain spiders, which, by the assistance of 

 these little air balloons, are wafted from place to place, 

 travelling in these airy chariots with perfect ease and 

 rapidity. Lister informs us that the height to which 

 spiders will thus ascend is prodigious ; and he himself, 

 from the top of the highest steeple in York Minster, 

 beheld these floating webs far above him. Of one par- 

 ticular species he says, t( Certainly this is an ex- 

 cellent rope-dancer, and is wonderfully delighted with 

 darting its threads ; nor is it only carried in the air, 

 I like the preceding ones, but it effects, itself, its ascent 

 and sailing ; for, by means of its legs closely applied to 

 each other, it, as it were, balances itself, and promotes 

 and directs its course no otherwise than as if Nature 

 had furnished it with wings or oars." * 



(147.) The crustaceous order of insects f, or the 

 crabs, have mostly eight legs and two claws, with which 

 their principal motions are accomplished. The latter 

 are especially their weapons of attack and defence, and 

 are wonderfully powerful. Lobsters, on the contrary, 

 have a very strong tail, which assists them both in 



* De Araneis, p. 85. 



f This we consider as the aquatic type of tlie.Agtera, according to the 

 natural system. 



