MOTIONS OF INSECTS. 345 
other; thorax deep brown with paler streaks ; abdomen. 
below dull white, above dark copper brown, with a den- 
tated white spot running longitudinally down the middle. 
The first of these, if distinct, as I suspect they are, agrees 
very well with the young of one which Lister observed as 
remarkable for taking aérial flights* ; and which I have 
most usually seen so engaged. The other may possibly 
be that before noticed, which he found in such infinite 
numbers in Cambridgeshire”. If this conjecture be cor- 
rect, it will prove that the same species first produce the 
gossamer that covers the ground, and then, shooting 
other threads, mount upon them into the air. 
My last query was, What causes these webs ultimately 
to fall to the earth? Mr. White’s observation will I 
think furnish the best answer. If the spiders have the 
power of coiling up their. webs in the air, as Dr. Lister 
affirms, then when they become heavier than the air they 
will fall*.” The more expanded the web, the lighter 
and more buoyant, and the more condensed, the heavier 
it must be. 
I trust you will allow from this mass of evidence, that 
the English Arachnologists—may I coin this term ?— 
were correct in their account of this singular phenomenon ; 
and think, with me, that Swammerdam (who however ad- 
mits that spiders sail on their webs), and after him De 
Geer, were rather hasty when they stigmatized the dis- 
covery that these animals shoot their webs into the air, 
and so take flight, as a strange and unfounded opinion ®. 
The fact, though so well authenticated, is indeed strange 
4 De Araneis, 66. » [bid. 79. © Nat. Hist. 1, 326. 
4 Swamm. Bibl. Nal. Ed. Hill, i. 24. De Geer, vii. 190, 
