This latter nest, the work of _N. Manderstjernæ_, Auss.[143] (formerly called _N. meridionalis_), has already been partially made known by the figures and description given of it in _Ants and Spiders_ (Plates IX., X., and XI., pp. 98, 100, and 104); but I have to confess, with great regret, that when these illustrations and descriptions were published, I was not fully acquainted with the true structure of this nest, having overlooked the existence of a short descending cavity which leaves the main tube a little above and on the opposite side to the ascending branch. This cavity is always present, but the very largest and oldest spiders usually allow it to become filled up with remains of food and particles of earth, and sometimes even spin silk across its entrance, in which case it can only be traced on very close examination. [Footnote 143: This spider was described by Mr. Pickard-Cambridge at p. 101 in _Ants and Spiders_, under the name of _N. meridionalis_, Costa. This name has now to be abandoned for reasons given in full by Mr. Cambridge at p. 283, below. It would appear that a spider discovered by M. Simon in Corsica corresponds more closely with the _N. meridionalis_ of Costa than our spider of the Riviera does. Moreover, since _Ants and Spiders_ was written I have had the good fortune to obtain at Mentone four male examples of our supposed _meridionalis_, and these prove to possess the same characters as those assigned by Prof. Ausserer to a male spider which was captured at Nice, and named by him _N. Manderstjernæ_. This specimen is now in the possession of Dr. L. Koch, to whom I am much indebted for having kindly entrusted it to me for examination. This enabled Mr. Pickard-Cambridge to assure himself of the specific identity of his _N. meridionalis_ with _N. Manderstjernæ_, which latter name it must for the future bear.] It was from an old nest such as this, in which the descending cavity had been closed up, that the large drawing at fig. A on Plate IX. of _Ants and Spiders_ was made, and this figure, therefore, still remains substantially correct. But in the case of the other illustrations--namely, fig. B, Plate IX., fig. A, Plate X., and figs. B and B 1, Plate XI., where nests of young spiders, or of spiders which, though adult, have not attained the maximum size, are represented, this descending cavity, though overlooked by me, should have been shown, for it must certainly have existed. Its presence was first observed by the Honourable L. G. Dillon, who detected it when tracing the course of the main tube upwards from below. I had always followed the tube from above downwards, and in so doing must have unwittingly filled up the descending cavity (the existence of which I was far from suspecting) with detached particles of earth.