This is the floor on which the Spider means to operate.
On this foundation, which acts as a protection from the sand, the Lycosa fashions a round mat, the size of a two-franc piece and made of superb white silk.

With a gentle, uniform movement, which might be regulated by the wheels of a delicate piece of clockwork, the tip of the abdomen rises and falls, each time touching the supporting base a little farther away, until the extreme scope of the mechanism is attained.
Then, without the Spider's moving her position, the oscillation is resumed in the opposite direction.

By means of this alternate motion, interspersed with numerous contacts, a segment of the sheet is obtained, of a very accurate texture.

When this is done, the Spider moves a little along a circular line and the loom works in the same manner on another segment.
The silk disk, a sort of hardy concave paten, now no longer receives anything from the spinnerets in its centre; the marginal belt alone increases in thickness.

The piece thus becomes a bowl-shaped porringer, surrounded by a wide, flat edge.
The time for the laying has come.