There is a family of spiders called by Blackwall _Ciniflonidæ_, see p. 17, which, besides the usual plain thread, make a peculiar kind of their own. They have in front of the spinnerets, Fig. 33, an additional spinning-organ called the cribellum, _a_, _a_. It is covered with fine tubes, much finer than those of the spinnerets, set close together. [Illustration: Fig. 33.] They also have on the last joint but one of the hind-legs a comb of stiff hairs, called the calamistrum, Fig. 34, on the upper side. [Illustration: Fig. 34.] [Illustration: Fig. 35.] When they spin their peculiar web, they turn one of the hind-legs across under the spinnerets, so that the calamistrum is just under the cribellum, and the foot rests on the opposite leg, Fig. 35. The hind-legs are then moved rapidly back and forth; so that the calamistrum combs out from the spinning-tubes, and at the same time tangles a band of fine threads, C. This band is laid along, and attached here and there to a plain thread, A, B, so as to make it adhere more readily to an insect that happens to touch it. As one leg gets tired, they change, and work with the other. In the webs of these spiders this adhesive band can be seen with the naked eye, running about, as in Fig. 36. The webs are usually irregular, and shaped to fit the place where they are built, but have, in some part, a tube somewhat like that of the grass spider, Fig. 24, where the owner hides. Sometimes they are more or less regular in structure, some of the threads being parallel, and crossed by shorter ones at regular intervals, Fig. 37. Others are circular, with a tube in the centre which runs into a crack, and from which radiate irregularly the principal threads of the web. Such webs are sometimes very numerous on stone buildings, and, as they collect large quantities of dust, seriously disfigure them. The webs alone, when clean, would not be noticed. [Illustration: Fig. 36.] [Illustration: Fig. 37.] THE TRIANGLE SPIDER. Among those spiders that use the calamistrum is one which makes a web unlike any other. It has been described by Professor Wilder, in the “Popular Science Monthly” for April, 1875, under the name of the “triangle spider.” It lives usually among the dead branches around the lower part of pine and spruce trees, and is colored so like the bark, that when it stands, as it usually does, on the end of a branch, it is easily mistaken for a part of it. The web seems to be made in the night. Wilder saw them early in the morning; and I, in the evening, between sunset and dark. A single thread five or six inches long runs from the spider’s roost; and from its extremity radiate four branches, attached to various twigs in the neighborhood, Fig. 38, AE, AF, AG, AH. [Illustration: Fig. 38.]