340 MOTIONS OF INSECTS. 



charioteers the gnats, for instance, which we have seen 

 sometimes rise in clouds into the air a may at these times 

 take place ; or the species of spiders that are most given 

 to these excursions, may not abound in their young 

 state when only they*can fly at other seasons of the 

 year. 



Whether the same species that cover the earth with 

 their webs produce those that fill the air, is to be our 

 next inquiry. Did the appearance of the one always 

 succeed that of the other, this might be reasonably con- 

 cluded : but the former, as I lately observed to you, 

 often occurs without being followed by the latter. Yet, 

 since it should seem that the aerial gossamer, though it 

 does not always follow it, is always preceded by the 

 terrestrial, this warrants a conjecture that they may be 

 synonymous. Two German authors, Bechstein b and 

 Strack c , have describee! the spider that produces gossa- 

 mer in Germany under the name of Aranea obtextrix c . 

 But it is not clear, unless they have described it at dif- 

 ferent ages, when spiders often greatly change their ap- 

 pearance, that they mean the same species. The former 

 describes his as of the size of a small pin's head, with its 

 eight eyes disposed in a circle, having a black-brown 

 body and light-yellow legs : while Dr. Strack represents 

 his A. obtextrix as more than two lines in length ; eyes 

 four in a square, and two on each side touching each 

 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. 



* VOL. I. 113. 



b Lichtenberg und Voight Magazin> 1789. vi. 53 . 



* Neuc Schriften for Naturforsch. &c. 1810. v. Heft. 41-56. 



