The eggs arc deposited (10 to 2000 in number) within silken cases or cocoons made by the mother spider for this purpose. The young spider on hatching is in general appearance much like the parent, but with larger hairs, and less distinctly marked. As the young spider grows, it is obliged to molt the skin. The number of molts varies from six to nine. The spider's silk is not used solely in the construction of webs, but serves a variety of purposes. With many spiders the web is a loose, irregular maze of crossed threads, which are the true 'cobwebs.' In other cases it. is a flat sheet of threads with a tubular retreat at one corner. The geometric or orb webs consist of a varying number of ra diating lines, crossed by many parallel or spiral threads. The whole is supported by sev eral guy-lines or stouter threads. At one corner or in the near vicinity is a silken nest or retreat, where the spider remains concealed during the day or when not using the web. This retreat is connected by a line to the centre of the web. When waiting for prey the spider rests upon the centre of the web, head downward and legs ex tended. See ORD-WEAVER.
The male spider is usually smaller than the female, with longer legs, and often is more highly colored; sometimes lie has additional spines on the legs, or spurs on the eoxre. In many of the minute species the male has the front of the cephalothorax greatly swollen and elevated, often molded into grotesque shapes. The courtship of spiders is frequently attended with grave peril to the male. The female, if not in the suitable temper, may attack and devour her devoted ad mirer. In some cases, however, the male is larger than his mate.
As a rule spiders can see clearly only for a few inches. They have an acute sense of hear ing, as well as of touch. A number of spiders are so shaped or colored as to deceptively re semble ants, an appearance heightened by their erratic movements. Others resemble the sur faces upon which they usually occur, as the bark of trees, dead leaves or twigs, and the petals of flowers. A few are able to produce sounds; some by rubbing the base of the abdomen over the base of the cephalothorax, others by rubbing the palpi against the sides of the mandibles. A considerable number, known as trap-door spiders, dig holes in the ground, line them with silk, and cover the entrance by a close-fitting door, the upper surface of which is made to resemble its surrounding. Some species make similar nests in trees. A few spiders aro social and produce webs in common, or closely connected to each other. Some of the large spiders are very power
ful and can kill small birds, rats, fish, and other animals. All spiders have poison-glands and use them in capturing p1•ey, but with most spiders the mandibles are so small and weak as to be incapable of piercing the human skin, and if they did so the small amount of poison in jected could have no deleterious effect. With the large tarantulas it is different, although cases of death from their bites are few- and doubtful. There is one group of spiders, however (genus Latrodeetus), which appear to merit the name of 'poisonous spiders.' The New Zealand species, locally known as `katipo' (q.v.), certainly ap pears to be dangerous. A species of Latrodectus occurs in the Southern United States, where it is called `malmignatte,' but its bite (as far as known) has not proved fatal.
The classification of spiders, formerly quite simple and based on their habits and webs, has undergone a complete revolution. Thirty-five or forty families are now known; several, however, contain but few species. The more prominent families may be grouped in two classes for con venience. Of the non-web-building kinds are the Thera phosidie, or tarantulas, and trap-door spiders. They have vertically moving fangs, four lung-slits, and are of large size. The Dysderidx possess but six eyes and live in dark places. The Drassida- are flat, with prominent spin nerets, and live on the ground or under stones. The Clubionkhr are convex and occur on bushes or among dead leaves. The Sparassidre are very flat and broad and are abundant in the tropics. The Thomisidx, or crab-spiders, are flat, broad, can walk sidewise, and catch prey by the fore legs. The Lycosithe, or wolf-spiders, have the eyes in three rows, those of the lowest very small; they wander in woods and fields. The Attidre, or jumping spiders, have eyes in three rows, those of the lowest row the largest; they jump, and stalk their prey.
Among web-building forms are the Agalenidx, which make flat sheets of web with a tubular retreat at one side; the Dietynithe, which possess a cribellum, and make irregular webs, with curled threads; the Theridiithe. which make the familiar cobweb; and the Epeirithe, which make geometric o• orb webs.
Consult: Emerton. The Common Spiders of the United States (Boston, 1902) ; McCook, Ameri can Spiders and Their Spinning Murk (Phila delphia, 1839) : Cambridge, The Spiders of Dor set (Sherbou•ne, 1879-81).