MOTIONS OF INSECTS. 469 



clear, unless they have described it at different ages, when spiders often 

 greatly change their appearance, 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 dentated 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 

 aerial flights *, and which I have most usually seen so engaged. The other 

 may possibly be that before noticed, which he found in such infinite num- 

 bers in Cambridgeshire. 2 If this conjecture be correct, 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." 3 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, admits that spiders sail on their webs), and after him De Geer, 

 were rather hasty when they stigmatised the discovery that these animals 

 shoot their webs into the air, and so take flight, as a strange and unfounded 

 opinion. 4 The fact, though so well authenticated, is indeed strange and 

 wonderful, and affords another proof of the extraordinary powers, unpa 

 ralleled in the higher orders of animals, with which the Creator has gifted 

 the insect world. Were, indeed, man and the larger animals, with their 

 present propensities, similarly endowed, the whole creation would soon go 

 to ruin. But these almost miraculous powers in the hands of these little 

 beings only tend to keep it in order and beauty. Adorable is that Wis- 

 dom, Power, and Goodness, that has distinguished these next to nothings 

 by such peculiar endowments for our preservation as if given to the strong 

 and mighty would work our destruction. 



After the foregoing marvellous detail of the aerial excursions of our in 

 sect air-balloonists, I fear you will think the motions of those which fly by 

 means of wings less interesting. You will find, however, that they are not 

 altogether barren of amusement. Though the wings are the principal 

 instruments of the flight of insects, yet there are others subsidiary to them, 

 which I shall here enumerate, considering them more at large under the 

 orders to which they severally belong. These are wing-cases {elytra, 

 tegmina, and hemelytra)\ winglets (alulae) ; poisers (halterei)\ tailets 

 (caudultB) ; booklets (hamiili) ; base-covers (teguke}; &c. Besides, their 

 tails, legs, and even antennce, assist them in some instances in this motion. 



As wings are common to almost the whole class, I shall consider their 

 structure here. Every wing consists of two membranes, more or less 



1 De Araneis, 66. 3 ibid. 79. * Nat. Hist. L 326. 



* Swamm. Bill. Nat. ed. Hill, i. 25. De Geer, vii. 190. 



HH 3 



