. American spiders et leur travail de bobinage. Une histoire naturelle de l'orbweaving spiders des États-Unis, avec une attention particulière pour leur industrie et les habitudes. Les araignées. Ennemis ET LEUR INFLUENCE. 415 il y aurait une autre ouverture et fermeture du nid jusqu'à sa fin a été accompli." c'est l'habitude, selon Moggridge, Simon et tous les observateurs qui ont noté le point du tout, pour ces animaux à accrocher vers le bas sur la surface intérieure de la porte. Dans de nombreux nids que j'ai vu il y a des trous le long du bord extérieur de la libre ou de porte la part directement en face de la charnière

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. American spiders and their spinning work. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits. Spiders. ENEMIES AND THEIR INFLUENCE. 415 there would be an alternate opening and shutting of the nest until his purpose was accomplished.' It is the habit, according to Moggridge, Simon, and all observers who have noted the point at all, for these animals to hang back downward upon the inner surface of the door. In many nests which I have seen there are holes along the outer or free edge of the door—the part directly opposite the hinge—which mark the points at which, probably, the fangs of the spider had been fixed, in order to give it a strong purchase against intruders. These holes are usually three, and show with great distinct- ness, even in the photograph from which Fig. 352 was drawn, which is the upper part of the nest of our California Trajidoor spider, Cteniza cali- fornica. X XII. One of the most remarkable developments of industrial skill under hostile influences is that described by Moggridge in the inner door of Nemesia congener. ^ The general character of the nest is that of a tube ten or twelve inches long, drilled horizontally into the side of a slope, and closed outside with a wafer door. This horizontal burrow bends abrupt- ly, and is continued perpendicularly down- ward, with a short branch extending upwards towards the surface. At the juncture or bending is suspended a wedge shaped double door, which tapers from below upwards to a hinge. The door has two crowns, separated from each other by the gusset like web of silk that connects the door on either side with the lining of the main tube. One of these crowns fits into and closes the main tube, while the other fits into the aperture of the upward branch. This swinging door acts very much in the fashion of a valve, dropping down to close the entrance from the first to the second tube, and swinging upward in such a way as to protect the

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