[Illustration: FIGS. 73, 74. Ariadne bicolor.--73, upper side enlarged four times. 74, under side.]
$Ariadne bicolor.$--Six eyes in three pairs, the side pairs separated by their diameter from the middle pair. The length is about a third of an inch, the cephalothorax and abdomen about the same length. The cephalothorax is long and the head wide. The maxillæ are long and narrow. The sternum is widest opposite the third legs (fig. 74), and ends behind in a blunt point. The first, second, and third legs are directed forward, the first pair longest and stoutest. The tibiæ of the first and second legs are a little thickened in the middle and have four pairs of spines on the under side, and the metatarsus of the same legs eight pairs. The hinder pairs of spinnerets are very small. The cephalothorax and legs are yellow brown, darker toward the front. The abdomen is purplish brown, darker in the middle and toward the front. In the male the head is more narrowed and the front legs longer. The front metatarsi are curved at the base and have a tooth each side, the inner one farthest from the tibia. The palpal organ is outside the tarsal joint, as it is in the Mygales.
The Thomisidæ are generally flat, short, and widened behind, and have a sidewise gait and crab-like appearance. The first and second legs are often much larger than the third and fourth, and all the legs extend sidewise from the thorax and not forward and backward, as they do in the Drassidæ (pp. 1-21). The feet have two claws and a thick brush of hairs. They are generally smooth or covered with very short and fine hair, and often have coarser hairs scattered at considerable distances from each other over the back. The eyes are small and in two slightly curved rows, the upper one longest and often much longer than the front row. The mandibles are small and narrowed toward the end. The maxillæ are narrow at the end and slant inward. Most of the species belong to the three following genera:
Xysticus (p. 30) is flat, with short legs, and marked with gray and brown, like bark and stones.
Misumena (p. 25) is white or brightly colored. The first and second legs are much longer than the third and fourth, and there is great difference between the sexes, the females being large and light colored, while the males are small, and yellow or green, with red and brown markings.