are enlarged, if let alone, till they are a foot or two feet wide, and remain till they collect dirt enough to tear them down by its weight. [Illustration: Fig. 24.] Nearly all spiders that make cobwebs live under them, back downward; and many are so formed, that they can hardly walk right side up. The spiders of the genus _Linyphia_ make a flat or curved sheet of web, supported by threads above and below; the spider standing, usually, underneath in some corner, out of sight. _Linyphia Marmorata_ makes a dome-shaped web, Fig. 25, supported by threads that extend up into the bushes two or three feet. The spider stands under the middle of the dome, where it draws in a small circle of web with its feet. The upper threads of the web interfere with the wings of small insects flying between them, and they fall down to the dome below, where they are seized, and pulled through the nearest hole. _Linyphia communis_ makes a double web, Fig. 26. The spider stands under the upper sheet, which curves a little downward. What the use of the lower web is, is not easily seen. Either of these spiders, when frightened, leaps out of the web to the ground; but _Linyphia communis_ must go to the edge before she can clear herself, and so is easily caught in her own web. [Illustration: Fig. 25.] [Illustration: Fig. 26.] A little spider, _Argyrodes_, belonging to the same family, lives among the upper threads of webs of this kind, without being troubled by the owner. It resembles in size and color the scales of pine-buds that often fall in the web, and may easily be mistaken for them. It probably spins a few threads of its own among the borrowed ones, and does, at times, make a separate web of its own. The webs of _Theridion_ usually have at some part a tent, or at least a thicker portion, under which the spider stands; and from this run irregularly simple threads, crossing each other in all directions, and held in place by threads above and below. Such irregular webs are made often in houses by _Theridion vulgare_, Hentz, in corners of rooms, under furniture, and in cellar-stairways. The same spider spins occasionally out of doors on fences, but never on plants. When it has caught an insect, and tied it up, it hoists it up into the web, sometimes a considerable distance. They do this by fastening to it threads from above, which, as they dry, contract, and pull it up a little. They keep on bringing down more and more threads, until the insect is at last hoisted to the top of the web, where they can suck it without exposing themselves. _Pholcus_, the long-legged cellar-spider, makes an irregular web of this kind, and has a curious habit when alarmed. It hangs down by its long legs, Fig. 27, and swings its body around in a circle, so fast that it can hardly be seen. Fig. 27, _a_, represents the spider as seen from below; and the dotted circle shows the path in which it revolves. ROUND WEBS.