Indeed it is not unlikely that these aged spiders may have come to a time of life when they no longer lay eggs, and so do not need to keep up all the defences which they employed when they had families to protect.
Since my attention was drawn to the existence of this cavity in the dwellings of _N. Manderstjernæ_ I have never noted the presence of young in those nests in which the cavity was filled up and disused; but then I have only exact records with reference to this point in the case of seven nests.
In these seven nests, however, there was no free cavity, and there were no young spiders, though it was at the season when it was common to find young in the nests.
The question, therefore, remains open, and further observations on this head would be very acceptable. I detected the _débris_ of insects, and especially the horny coats of ants, in the descending cavity, in many nests; and in some of the oldest, where it had become completely blocked up, these remains still indicated its former outlines and position.
The nests of _N. Manderstjernæ_ at Cannes correspond both in respect of the cavity and of their other characteristics with those at Mentone. _N. Manderstjernæ_ occurs pretty abundantly at San Remo in the olive-grounds east of the Sanctuary, but I can say nothing as to whether the nests there possessed the cavity or not, for, when I was there, I was not aware of its existence. I obtained a single example of _N. Manderstjernæ_ and its nest at Hyères, and this is the westernmost point at which this species has as yet been detected.
We have now passed in review all the seven known types of true trap-door nest, and have taken note also of the lower and more rudimentary forms of nest, such as that of _Atypus_, and the funnel nest of _Cyrtauchenius elongatus_, neither of which is furnished with a door.
Among the true trap-door nests, those of the cork type stand in a measure alone, being distinguished from all the others by their solid surface doors, composed of many layers of silk and earth; and we do not at present know of any intermediate forms linking the cork and wafer types together. But among the various nests which represent the wafer type the case is different, for here the types naturally fall into a progressive series, such as that represented in the diagrams (Pl. XIV., p. 193).