Plate XI, fig. A. — The upper part of a nest of "Nemesia meridionalis" concealed in a plant of Ceterach fern ; A 1 and A 2, a minute cork-door, closed and open, which I saw constructed by a very young spider "Cteniza fodiens", or, more probably, "Nemesia caementaria" at the mouth of a hole in the mass of earth containing the nest of "N. meridionalis" figured at A. This hole may be seen on the right of the fern. B, the door of a small nest of "N. meridionalis", as seen from above, in its natural position in a steeply sloping bank ; B I, part of the same nest placed in an upright position, and showing the surface door open and the lower door closing the branch; B 2, the same with the lower door pushed across so as to close the main tube ; B 3, 4, and 5, different views of this second door. the figures in this plate are of the natural size.