roof for its nest of dried grass. That those old spiders' dens are not accidentally chosen by the mouse, appears from the fact, that out of about a dozen mouse-nests of this sort found during winter in a copse between Lewisham and Bromley, Kent (England), every second or third one was furnished with such a roof.
The Water Spider.—We extract the following exquisitely beautiful and interesting fact in nature, connected with diving operations, from the Rev. Mr. Kirby's Bridgewater Treatise:—
"The Water Spider is one of the most remarkable upon whom that office (diving) is developed by her Creator. To this end, her instinct instructs her to fabricate a kind of diving-bell in the bosom of that element. She usually selects still waters for this purpose. Her house is an oval cocoon, filled with air, and lined with silk, from which threads issue in every direction, and are fastened to the surrounding plants; in this cocoon, which is open below, she watches for her prey, and even appears to pass the winter, when she closes the opening. It is most commonly, yet not always, entirely under water; but its inhabitant has filled it with air for her respiration, which enables her to live in it. She conveys the air to it in the following manner: she usually swims upon her back, when her abdomen is enveloped in a bubble of air, and appears like a globe of quicksilver[1]; with this she enters her cocoon, and displacing an*
- ↑ Her singular economy was first, we believe, described by Clerck (Aranei Suecici, Stockholm, 1757.), L. M. de Lignac (Mem. des Araign. Aquat., 12mo. Paris, 1799.), and De Geer. "The shining appearance," says Clerck, "proceeds either from an inflated globule surrounding the abdomen, or from the space between the body and the water. The spider, when wishing to inhale the air, rises to the surface, with its body still submersed, and only the part containing the spinneret rising just to the surface, when it briskly opens and moves its four teats. A thick coat of hair keeps the water from approaching or wetting the abdomen. It comes up for air about four times an hour or oftener, though I have good reason to suppose it can continue without it for several days together. "I found in the middle of May one male and ten females, which I put into a glass filled with water, where they lived together very quietly for eight days. I put some duck-weed (Lemna) into the glass to afford them shelter, and the fe-*
