has given an admirable description of one of these single door wafer nests, the work of Cteniza nidulans, which I cannot do better than quote:—
The nest is "cylindrical, or nearly so, from four to ten inches deep, and about one inch in diameter; the bottom is rounded; and the top, which is at the surface of the soil, is closed very accurately with a circular lid. They are not all equally finished, some being much more compact, and having the lid more closely fitted than others. Some have irregular bulgings, and ragged laminated offsets on the outer surface; but all are smooth and silky on the inside. . . . The mouth of the tube, and the parts near it, are very strong; the walls here often having a thickness of from one-*eighth to one-fourth of an inch; but the lower parts are much thinner. The lid is continuous with the tube for about a third of its circumference, and this part may be called the hinge, though it presents no structure peculiar to itself; it is simply bent at a right angle, as is manifest, if a nest be cut longitudinally through with scissors, the incision passing through the midst of the lid. The mode of construction, I judge, from examination of many nests, to be this. The spider digs a cylindrical hole in the moist earth, with her jointed fangs or mandibles, carrying out the fragments as they are dislodged. When the excavation has proceeded a little way, she begins to spin the lining which forms the dwelling. I conclude thus, because nests are occasionally found a few inches in length, with the lid and upper part perfect, but without any bottom, these being evidently in the course of formation. I suppose that she weaves her silk at first in unconnected patches, against the earthy sides,
