Agelenidae (sheet-web spiders; order Araneae, suborder Araneomorphae) Family of spiders that construct sheet webs with lateral, tubular retreats, and that have a somewhat elongate appearance, with a flattened thorax. The sternum is wide, heart-shaped, and may project between the fourth coxae. The chelicerae are usually very convex, and nearly vertical, the outer margin having three teeth, the inner two eight teeth. The carapace (see CEPHALOTHORAX.) is oval, narrowed, and anteriad; and has a longitudinal depression (sometimes replaced by a dark line), with patterns of dots and bars. The head is raised and narrow, and points forward, and the eyes, usually uniform in size, are arranged in two short rows. The legs are thin and long, are covered thickly with long hairs, and are spiny, especially on the third and fourth pairs. The anterior spinnerets are cylindrical, and more or less separated; the median spinnerets are similar or smaller; and the posterior spinnerets are usually two-segmented and long. The tracheal spiracle is close to the spinnerets. All species in this family, including Tegenaria domestica (house spider), catch prey on the upper surface of the sheet web. Many species spend a long time together as couples. Distribution is worldwide. Argyroneta aquatica (water spider), the only species of spider to live permanently below water, is usually placed in this family, but sometimes in a family of its own.
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