They walk backward or sidewise as well as forward, and many of them jump great distances. They make no cobwebs, but some species make silk tubes or bags on plants or under stones in which they hide to molt or lay their eggs or to pass the winter. There are often great differences in color and markings between the sexes, and the males have peculiar bunches of hairs and color spots on the legs and head. At the mating time some of the males have peculiar ways of approaching the female, holding their legs extended sidewise or over their heads in such ways as to display their ornaments. These mating habits have been well described by G. W. Peckham, who has made a special study of this family, in the Occasional Papers of the Wisconsin Natural History Society, of Milwaukee, in 1889. This family is largely represented in more southern countries, and our species belong to a great number of genera most of whose members live farther south.

Attus palustris.—Large females are quarter of an inch long, the males a little smaller. The cephalothorax is a quarter longer than wide, shorter in proportion to its width than in the next species, Saitis pulex, which it much resembles. The two sexes resemble each other in markings, but the females are lighter and browner and the males darker and grayer. The cephalothorax has a narrow white middle line, widened opposite the dorsal eyes, and a shorter white line just below the eyes on the sides [(fig. 119)]. The edge of the cephalothorax is also white. On the abdomen the front middle spot is not so distinct as in pulex, but in place of it are two white spots. Behind these is a large transverse light marking, sometimes broken into two spots. The legs are dark or light gray, without any distinct markings. The male palpi are smaller than in pulex, though the males are larger. Palustris lives on plants and makes nests among the leaves.

Saitis pulex.—This is one of the smallest of the family. It is about a sixth of an inch long, sometimes even smaller. The colors are various shades of gray like the ground, and when still it is hard to find, but it is an active spider and exposes itself by jumping in open places. The cephalothorax is half longer than wide, longer and narrower than in Habrocestum and Attus. The abdomen is usually shorter than the cephalothorax and wider (figs. [120, 121]). The cephalothorax has a large light-colored triangle in the middle, covering the head between the eyes in front and ending in a point behind. In alcohol this spot disappears, especially in the males, and the head appears black between the eyes and light behind and at the sides. The front half of the abdomen has a light middle stripe, lightest at the edges and darker gray in the middle. Behind this is a transverse white spot nearly the whole width of the abdomen and behind it several smaller light markings. In the male these markings are brighter and the surrounding dark color blacker than in the females. The legs are marked with indefinite spots of dark gray on a lighter ground, the contrast stronger in the males. The hairs all over the body are short and fine and the spines on the legs distinct, especially in the males.