probably only serve to enable them to tell night from day. I think
these spiders are mainly guided by a marvelously acute tactile sense.
They probably feel the slightest vibration in the earth or air, unless
they have a sixth sense of which we know nothing.

All their work, the building and repairing of their nests, as well as
all their hunting, is done by night. This habit, in connection with
their extreme shyness, makes the task of getting at their life-histories
a difficult one. The inside of the burrow seems coated with a finer and
harder substance than the soil in which they are dug. It is made on the
spot, the spider mixing some secretion of her own with the clay, and
working it up into a finer product.

The trap-door sooner or later wears out at the hinge, and is then
discarded and a new door manufactured. We saw many nests with the old
door lying near the entrance. The door is made of several layers of silk
and clay, and is a substantial affair.

The spider families all have the gift of genius. Of what ingenious
devices and arts are they masters! How wide their range! They spin, they
delve, they jump, they fly. They are the original spinners. They have
probably been on their job since carboniferous times, many millions of
years before man took up the art. And they can spin a thread so fine
that science makes the astonishing statement that it would take four
millions of them to make a thread the caliber of one of the hairs of our
head--a degree of delicacy to which man can never hope to attain.

Trap-doors usually mean surprises and stratagems, secrets and betrayals,
and this species of the arachnids is proficient in all these things.

The adobe soil on the Pacific coast is as well fitted to the purposes of
this spider as if it had been made for her special use. But, as in all
such cases, the soil was not made for her, but she is adapted to it. It
is radically unlike any soil on the Atlantic coast--the soil for canons
and the rectangular watercourses, and for the trap-door spider. It is a
tough, fine-grained homogeneous soil, and when dry does not crumble or
disintegrate; the cohesion of particles is such that sun-dried brick are
easily made from it.

This spider is found in New Mexico, Arizona, California, and Jamaica. It
belongs to the family of _Mygalidae_. It resembles in appearance the
tarantula of Europe, described by Fabre, and has many of the same
habits; but its habitation is a much more ingenious a