. The Cambridge natural history. Zoology. 3SO ARACHNIDA ARAN EAE not belong to the Epeiridae but to the cribellate Uloboridae, but its defective orb-web is so curious that it deserves a special mention. A single foundation-line is laid down, and from it four radii are drawn. and are connected with cross lines, the snare constituting about one-sixth of a circle. From the centre of the incom- plete circle a thread proceeds to some more or less distant object, and on this the spider takes up its position, inverted, and hauls in the line A, Snare of Hypliotes cacatiis ; B, enlarged till the Snare
. The Cambridge natural history. Zoology. 3SO ARACHNIDA ARAN EAE not belong to the Epeiridae but to the cribellate Uloboridae, but its defective orb-web is so curious that it deserves a special mention. A single foundation-line is laid down, and from it four radii are drawn. and are connected with cross lines, the snare constituting about one-sixth of a circle. From the centre of the incom- plete circle a thread proceeds to some more or less distant object, and on this the spider takes up its position, inverted, and hauls in the line A, Snare of Hypliotes cacatiis ; B, enlarged till the Snare is taut. Pig. 191 view of the Spider, sliowing tlie liauled-in line. (After Emerton. •slack" of the When the trembling of the line shows the spider that an insect has struck the net, it lets go with its fore legs, and the web, springing back to its normal position, entangles the intruder more thoroughly by its vibrations. When large insects are in question the spider has been observed to " spring'' the net several times in succession. H. cavatus is common in the pine woods of Pennsylvania, but the only English species, 11. 2Mradoxus, is extremely rare. A remarkable spider has been discovered in Texas by M'Cook, which, after building a horizontal orb-web, converts it subsequently into a dome (Fig. 192) of exceedingly perfect form. It is named Epeira hasilica, and has been the object of careful study by Dr. Marx, who observed the whole process of web-construction. Threads are attached at various points on the upper surface of the horizontal wheel, the central portion of which is gradually pulled up until the height of the dome is nearly equal to the diameter of its base. But the snare of this spider does not consist of the dome alone. A sheet of irregular lines is stretched below, while above there is a maze of threads in the form of a pyramid. Several other Orb-weavers, as, for instance, U. lalnj- rinfJiea and JH. triarama, supplement their typical webs by an. Please
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