HABITATIONS OF INSECTS. 267 



diameter, forming a cylindrical bag of dark-coloured silk, closed at the 

 bottom, and accurately fitted at the top by a door or lid. 1 



The habitation of Argyroneta aquatica, the other spider to which I 

 alluded, is chiefly remarkable for the element in which it is constructed and 

 the materials that compose it. It is built in the midst of water, and formed, 

 in fact, of air ! Spiders are usually terrestrial, but this is aquatic, or rather 

 amphibious ; for though she resides in the midst of water, in which she 

 swims with great celerity, sometimes on her belly, but more frequently on 

 her back, and is an admirable diver, she not unfrequently hunts on shore, 

 and having caught her prey, plunges with it to the bottom of the water. 

 Here it is she forms her singular and unique abode. She would evidently 

 have but a very uncomfortable time were she constantly wet, but this she 

 is sagacious enough to avoid ; and by availing herself of some well-known 

 philosophical principles, she constructs for herself an apartment in which, 

 like the mermaids and sea-nymphs of fable, she resides in comfort and 

 security. The following is her process. First she spins loose threads in 

 various directions attached to the leaves of aquatic plants, which may be 

 called the frame- work of her chamber, and over them she spreads a trans- 

 parent varnish resembling liquid glass, which issues from the middle of her 

 spinners, and which is so elastic that it is capable of great expansion and 

 contraction ; and if a hole be made in it, it immediately closes again. Next 

 she spreads over her belly a pellicle of the same material, and ascends to 

 the surface. The precise mode in which she transfers a bubble of air 

 beneath this pellicle is not accurately known ; but from an observation 

 made by the ingenious author of the little work from which this account is 

 abstracted, he concludes that she draws the air into her body by the anus, 

 which she presents to the surface of the pool, and then pumps it out from 

 an opening at the base of the belly between the pellicle and that part of the 

 body, the hairs of which keep it extended. Clothed with this aerial mantle, 

 which to the spectator seems formed of resplendent quicksilver, she plunges 

 to the bottom, and, with as much dexterity as a chemist transfers gas with 

 a gas-holder, introduces her bubble of air beneath the roof prepared for its 

 reception. This manoeuvre sh,e repeats ten or twelve times, until at length 

 in about a quarter of an hour she has transported as much air as suffices 

 to expand her apartment to its intended extent, and now finds herself in 

 possession of a little aerial edifice, I had almost said an enchanted palace, 

 affording her a commodious and dry retreat in the very midst of the water. 

 Here she reposes unmoved by the storms that agitate the surface of the 

 pool, and devours her prey at ease and in safety. Both sexes form these 

 lodgings. At a particular season of the year the male quits his apartment, 

 approaches that of the female, enters it, and enlarging it by the bubble of 

 air that he carries with him, it becomes a common abode for the happy 

 pair. 2 The spider which forms these singular habitations is one of the largest 

 European species, and in some countries not uncommon in stagnant pools. 



I am, &c. 



1 See several Memoirs upon this and some allied species by Messrs. Sells, 

 Saunders, and Westwood, in the Trans, of the Ent. Soc. of London, vols. ii. and iii. 



2 Memoirepour servir a commencer I'Histoire des Araignees Aquatiques, 12mo. 



