The Dysderidæ are a small family of spiders resembling in their general
appearance the Drassidæ, but differing from them in several important
characters. They have only six eyes instead of the usual eight, and they
have four breathing holes in the front of the abdomen, two of them
leading to the usual lungs and the others to the air-tubes, which in
most spiders open just in front of the spinnerets.
[Illustration: FIGS. 70, 71, 72. Dysdera interrita.--70, enlarged four
times. 71, head and eyes from in front. 72, under side enlarged six
times.]
$Dysdera interrita.$--Six eyes close together on the front of the head.
Length half an inch, with the abdomen a little longer than the
cephalothorax. The coxæ and patellæ are unusually long, especially on
the front legs, and the tarsi are unusually short (fig. 70). The
mandibles are long and inclined forward. The maxillæ are long, a little
widened in the middle and pointed at the ends. The labium is long and
narrow, and forked at the end (fig. 72). The skin around the base of the
legs is thick and hard, so that the sternum appears to extend between
them (fig. 72). There are two tracheal openings just behind the
openings of the lungs. The cephalothorax and legs are orange brown,
darker toward the front. The abdomen is the same color, but so pale as
to be almost white.
[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.