All spiders kill the insects and other small creatures on which they prey by means of their venomous mandibles, and the bite of a house spider is quickly fatal to a house-fly "he bite of the larger species is dreaded even by man, being very painful, and not only •odueing much intlamination and swelling, but often much fever. Death has been 1...lown to ensue.
Spiders' wells have long been in high repute for stanching womids. Threads cf tl.is material are also employed for the cross-wires of astronomical telescopes. Textile fabrics have been made of it, but only as articles of curiosity.
Spiders have been arranged by Waleknaer in five principal groups, distinguished by their habits. (1.) Hunting spiders, which incessantly run about in the Nieinity of their abode in quest of prey, some of theni weaving silken tubes, in which they dwell, others hiding in fissures; sonic remarkable for the swiftness with which they rue, others for their power of leaping in order to seize their prey. Sonic of them are of large size. Livingstone mentions a South African one which can leap a distance of one foot. A small one is common on windows in Britain in summer, and, when leaping, avoids the danger of falling from the window by suspending itself at the same moment by a thread. (2.)16ilndering spiders, which have no fixed residence, have the power of running side ways or backwards, and throw out threads to entrap prey, but do not weave them into regular webs. Sonic of them live among plants, and place their egg-cases on leaves, the edges of which they bind together with their silk. (3.) Prowling spiders, which have nests, but prowl about in their neighborhood, or in that of the threads which they spread to catch prey. (4.) Sedentary spiders, such as the common house spider, which spin large webs, and lie in wait at the middle or at the side. These are subdivided according to the fashion and structure of their webs. (5.) Water spiders, which resem ble the last group in their habits, except that they live in water, generally among the stems and leaves of aquatic plants, where they construct their webs. A very interesting
species, one of the most interesting possible inmates of an aquarium, is the common water spider (argyroneta tiguatica) of Britain, not unfrequently to be found in deep ditches and ponds in some parts of England. It is of a brownish color, densely covered with hairs, which are of great importance in its economy, entangling air, which the animal carries down with it into the water, to supply its pulmonary sacs; for the water spiders all breathe by the same kind of organs as their terrestrial congeners. The eggs of the water spicier arc attached to the leaves or stems of plants under the surface of the water, and are protected by a dome-shaped web, so close in its structure as to retain the air which is brought into it, and in which the spider itself lives, bringing down air on its furred body till the dome is filled. The entrance is from below.—The most curi ous nests are those of the trap-door spiders, belonging to the group territelarice, or under ground weavers. The nest is a tubular burrow, lined with silk, and haiiug the entrance covered with a circular lid of the same material attached to the edge of the lining by a kind of hinge. In the most common form of nest, the lid is Made thick by having lay ers of earth between the layers of silk, and fits like a cork into the mouth of the tube, which is beveled to receive it. As mosses grow on the lid as well as on the surround ing ground, the concealment is complete. 11 some types of nest, there is a thin external door, and then one of a more solid kind some inches below, behind Which the inmate can place itself, aud resist the intrusion of an enemy. In one kind of these double-door nests, a side gallery branches off from the main one, and the external door is so placed at the angle that it can be made to shut either.