In my concluding remarks in _Ants and Spiders_ I called attention to the importance which attaches to a knowledge of the food and manner of feeding of any creature whose life-history we may wish to study, and I would now once more press the subject on the attention of my readers. For the range and distribution of a species largely depends upon the nature of its food, and this will also be an indication of the rivals with which it has to compete in the struggle for existence; the times and seasons of its activity, and in many cases even the structure and position of its dwelling-place will be governed by this same all-important question of food-supply. I have now detected the remains of insects, and of ants especially, in the nest of every species of trap-door spider which I have examined _in situ_; very frequently, however, one may open several nests in succession without finding any of these _débris_, and at other times they will only be detected beneath the existing bottom of the tube, layers of silk having been spun over successive layers of refuse. The horny coats of ants form by very far the largest proportion of these remains, and I have lately been much struck by the number of instances in which, while digging out ants' nests at Mentone, I have found trap-door nests (especially those of _N. Manderstjernæ_ and _N. Moggridgii_) in their midst, the tubes often traversing the very heart of the ants' colony and coming into close contact with the galleries and chambers of the ants. The doors in these instances had almost always escaped my notice, and, indeed, they so closely resembled the surface of the ground that even when I knew, from having accidentally cut across the tube below ground, that one of these doors must lie near a given spot, yet I could only discover it by following the passage from below upwards. This perfect concealment is doubtless of essential importance to the spiders' success in life, for, if they once alarmed the whole colony of ants and let them know the exact whereabouts of their lurking-place, they would soon learn to avoid it. But, as it is, the work of opening the door, snatching in an ant, and closing it again, is but the affair of a second or two, and before the companions of the victim have time to realize the nature of the phenomenon, the gaping earth has closed again and become once more, to all appearance, part of the solid and trustworthy ground. I have seen _N. Manderstjernæ_ snatch at insects in this way during the daytime, and I well remember how I started on one occasion when, as I was looking fixedly at a small blue gnat which I had taken for a moth, I saw the earth suddenly open and one of these spiders partly emerge, make a swift stroke at the insect, and withdraw again as swiftly.