[Illustration: FIGS. 469, 470.--469, cribellum. 470, calamistrum of
Amaurobius sylvestris.]
This group comprises several families that differ greatly in form and
habits, but agree in having peculiar spinning organs, different from
those of all the other spiders. They have the usual six spinnerets and
in addition the cribellum (fig. 469), a flat, wide spinning organ, close
in front of the other spinnerets and covered with finer spinning tubes.
Besides this additional spinning organ they have on the hind legs the
calamistrum (fig. 470), a row of hairs that is used to draw out a loose
band of silk from the spinnerets. Most of our species belong to the
genera Dictyna and Amaurobius and resemble Tegenaria (pp. 96-99) in
their feet with three claws, in the arrangement of the eyes, and in
their general form and color. The others belong to the small and
peculiar genera Filistata, Hyptiotes, and Uloborus.
[Illustration: FIG. 471. Webs of Dictyna on the side of a house. The
nests were in the groove between the boards, and the webs radiated
irregularly from them, crossing each other in all directions so as to
appear like parts of one web.]
[Illustration: FIG. 472. Web of Dictyna in the corner of a window pane.]