One of its most distinctive features is found in the shape of the lower door, fig. F 1, Plate XIV., and figs. A 1, A 2, Plate XVIII., which may be said to be double, presenting two crowns, one of which fits into the main tube and the other into the branch, but I could not see my way to employing this character in naming the type. The nest is, however, quite distinct from all the others, and is inhabited by a new species of trap-door spider (_N. congener_, Camb.[142]). The characteristic portions of this nest are shown in Plate XVIII., and fig. A 3, in the same Plate, represents its occupant. [Footnote 142: Mr. Pickard-Cambridge's description will be found at p. 292, below. In its characters this female spider (the male is unknown) most nearly resembles _N. cæmentaria_, but differs, among other points, in markings and in having one or more spines on the genual joint of leg, these spines being almost always absent in the same joint in _cæmentaria_. The nests of the two species are totally unlike.] The hedge-banks near Hyères, and also about the railway station of the same name, which is some 4 miles from the town itself, are frequently tenanted by this spider. During a short stay there in May, 1873, I secured a large number of specimens, and verified the structure of the nest by a careful examination of thirty-eight examples. The nest is invariably branched and furnished with a lower door, but the branch is of variable length, usually short, and never, as far as I could detect, quite reaches the surface. In some cases this branch was so short that it could scarcely contain the spider, and, under these circumstances, it is not easy to conceive any other use for it than that of retaining the lower door when not in use. It may, however, enable the spider to take up a rather better position when engaged, as she frequently is if disturbed, in keeping the main tube closed by pressing the lower door upwards with her feet, for then her head points downwards, and her abdomen rests in the branch. [Illustration: _Plate XVIII._] I have seen her in this attitude on several occasions when I had cut out a block of earth similar to that figured in the plate. The lower door is quite unlike that of either of the other two double-door wafer nests, being wedge-shaped, tapering from below upwards to the hinge, which is always placed at the point of bifurcation of the tubes, and having two crowns separated from each other by the gusset-like web of silk which connects the door on either side with the lining of the main tube, one of these crowns fitting into and closing the main tube, while the other fits into the aperture of the branch.