Geometric Net of Epeira diadema.

lines are not simple, but in form of a Y, giving her the additional security of two attachments instead of one.

In constructing the body of the net, the most remarkable circumstance is her using her limbs as a measure, to regulate the distances of her radii or wheel-spokes, and the circular meshes interweaved into them. These are consequently always proportional to the size of the spider. She often takes up her station in the centre, but not always, though it is so said by inaccurate writers; for she as frequently lurks in a little chamber constructed under a leaf or other shelter at the corner of her web, ready to dart down upon whatever prey may be en

tangled in her net. The centre of the net is said also to be composed of more viscid materials than its suspensory lines, a circumstance alleged to be proved by the former appearing under the microscope studded with globules of gum.* We have not been able to verify this distinction, having seen the suspensory lines as often studded in this manner as those in the centre.t

MASON-SPIDers.

A no less wonderful structure is composed by a sort of spiders, natives of the tropics and the south of Europe, which have been justly called masonspiders by M. Latreille. One of these (Mygale nidulans, WALCKN.), found in the West Indies, "digs a hole in the earth obliquely downwards, above three inches in length, and one in diameter. This cavity she lines with a tough thick web, which, when taken out, resembles a leathern purse; but what is most curious, this house has a door with hinges, like the operculum of some sea-shells, and herself and family, who tenant this nest, open and shut the door whenever they pass and repass. This history was told me," says Darwin, "and the nest, with its door, shown me by the late Dr. Butt, of Bath, who was some years physician in Jamaica." ‡

The nest of a mason-spider, similar to this, has been obligingly put into our hands by Mr. Riddle, of Blackheath. It came from the West Indies, and is probably that of Latreille's clay-kneader (Mygale cratiens), and one of the smallest of the genus. We have since seen a pair of these spiders, in possession of Mr. William Mello, of Blackheath. The nest is composed of very hard argillaceous clay, deeply tinged with brown oxide of iron. It is in * Kirby and Spence, Intr. i. 419. † J. R. Darwin's Zoonomia, i. 253, 8vo. ed.

form of a tube, about one inch in diameter, between six and seven inches long, and slightly bent towards the lower extremity-appearing to have been mined into the clay rather than built. The interior of the tube is lined with a uniform tapestry of silken web, of an orange-white colour, with a texture intermediate between India paper and very fine glove leather. But the most wonderful part of this nest is its entrance, which we look upon as the perfection of insect architecture. A circular door, about the size of a crown-piece, slightly concave on the outside and convex within, is formed of more than a dozen layers of the same web which lines the interior, closely laid upon one another, and shaped so that the inner layers are the broadest, the outer being gradually less in diameter, except towards the hinge, which is about an inch long; and in consequence of all the layers being united there, and prolonged into the tube, it becomes the thickest and strongest part of the structure. The elasticity of the materials, also, gives to this hinge the remarkable peculiarity of acting like a spring, and shutting the door of the nest spontaneously. It is, besides, made to fit so accurately to the aperture, which is composed of similar concentric layers of web, that it is almost impossible to distinguish the joining by the most careful inspection. To gratify curiosity, the door has been opened and shut hundreds of times, without in the least destroying the power of the spring. When the door is shut, it resembles some of the lichens (Lecidea), or the leathery fungi, such as Polyporus versicolor, (MICHELI,) or, nearer still, the upper valve of a young oyster shell. The door of the nest, the only part seen above ground, being of a blackish-brown colour, it must be very difficult to discover.*

Another mason-spider (Mygale cæmentaria, LATR.),

* J. R.

Y

found in the south of France, usually selects for her nest a place bare of grass, sloping in such a manner as to carry off the water, and of a firm soil, without rocks or small stones. She digs a gallery a foot or two in depth, and of a diameter (equal throughout) sufficient to admit of her easily passing. She lines this with a tapestry of silk glued to the walls. The door, which is circular, is constructed of many layers of earth kneaded, and bound together with silk. Externally, it is flat and rough, corresponding to the earth around the entrance, for the purpose, no doubt, of concealment on the inside it is convex, and tapestried thickly with a web of fine silk. The threads

A. The nest shut. B. The nest open. C. The spider, mygale comentaria. D. The eyes magnified. E, F. Parts of the foot and claw magnified.

of this door-tapestry are prolonged, and strongly attached to the upper side of the entrance, forming an excellent hinge, which when pushed open by the spider, shuts again by its own weight, without the aid of spring hinges. When the spider is at home, and her door forcibly opened by an intruder, she pulls it strongly inwards, and even when half-opened often snatches it out of the hand; but when she is foiled in this, she retreats to the bottom of her den, as her last resource.'

*

Rossi ascertained that the female of an allied species (Mygale sauvagesii, LATR.), found in Corsica, lived in one of these nests with a numerous posterity. He destroyed one of these doors to observe whether a new one would be made, which it was: but it was fixed immoveably, without a hinge; the spider, no doubt, fortifying herself in this manner till she thought she might re-open it without danger.†

"The Rev. Revett Shepherd has often noticed, in the fen ditches of Norfolk, a very large spider (the species not yet determined) which actually forms a raft for the purpose of obtaining its prey with more facility. Keeping its station upon a ball of weeds about three inches in diameter, probably held together by slight silken cords, it is wafted along the surface of the water upon this floating island, which it quits the moment it sees a drowning insect. The booty thus seized it devours at leisure upon its raft, under which it retires when alarmed by any danger." In the spring of 1830, we found a spider on some reeds in the Croydon Canal, which agreed in appearance with Mr. Shepherd's.

Among our native spiders there are several besides * Mem. Soc. d'Hist. Nat. de Paris, An. vii. † Ibid. p. 125, and Latreille, Hist. Nat. Génér. viii. p. 163. Kirby and Spence, Intr. i. 425.