Measurements.—Taken lengthwise (for the lids of the adult specimens are seldom exactly circular) (fig. 7, e), the lid measures ⅗ in. to ⅖ in. The lids always vary in thickness. If a nest is located in a mossy bank, the lid is thick, so that the surrounding growths will spread to the surface of the door. If the lid is situated in a hard, bare, clay bank, the spider, not needing to provide rooting-surface, covers the door with a thin cement layer. A thick door is often ⅙ in. through; a thin door often less than ½4 in.

Construction of Lid.—The adult's lid is a compound structure, consisting of several layers. The number of layers is never less than two, and seldom more than twelve. Where the bank is mossy, the layers are generally two—viz., a thin silk layer and a thick earth layer. If the locality is dry and poor in growths, the lid has one very thin cement-clay layer on top, and from four to twelve separate silken layers (fig. 7, a, b, c, d, e—stages in growth).

Layers of Lid.—Many adult lids show a rough, layered upper surface (fig. 7, e) caused by the enlargements of the door. Each silken layer is thicker at the edges than in the centre, and appears in texture like a piece of linen. The material for the top, or the earthy layer, is scraped from near the nest, and fine stones and pieces of vegetation are frequently mixed together with the earth; hence the door becomes very inconspicuous. Where the bank is lumpy, doors are sometimes constructed from small, entire, irregular pieces of earth, cut flat on one side, and hinged.

Situation of Hinge.—The tube of the nest is very seldom straight, but enters the ground with a curve (figs. 9, 10, 13, &c.). The hinge is invariably situated towards the curved terminus of the tube. Fig. 13 shows the natural position of tube, the hinge being on top, and hence the door always shuts with its own weight. The hinge is often with only one layer, but the remaining layers (sometimes five in number) are continued above the hinge itself with a little upward twist (fig 9, a, just above arrow). This silken projection only allows the door to rise to an angle of 60°. Often the side near the hinge is sunken into the ground, a ridge hangs over the depression (fig. 9, b and c, near the arrow);