heir domesticated fellows, but this trait seems to me worthy of
remark; it proves a very developed power of observation and
reflection.

[Illustration: FIG. 20.]

[Illustration: FIG. 21.]

The Trap-door Spiders of the south of Europe construct burrows which
have been studied with great care and in much detail by Moggridge.[83]
He found that there were four chief types of burrow, shown in the
accompanying illustration (Fig. 20) at about one-third the actual size
(except C1 and D1, which are of natural size). While A and B have only
one door, C and D, besides the surface door, have another a short way
under ground. The whole burrow as well as the door are lined with
silk, which also forms the hinge. The great art of the Trap-door
Spider lies in her skilful forming of the door, which fits tightly,
although it opens widely when she emerges, and which she frequently
holds down when an intruder strives to enter, and in the manner with
which the presence of the door is concealed, so as to harmonise with
surrounding objects. Perhaps in no case is the concealment more
complete than when dead leaves are employed to cover the door. In some
cases a single withered olive leaf is selected, and it serves to cover
the entrance; in other cases several are woven together with bits of
wood or roots, as in the accompanying illustration, which represents
such a door when open and when shut. (Fig. 21.)

[83] J. T. Moggridge, _Harvesting Ants and Trap-door
Spiders_, contained in two elaborately illustrated volumes,
London, 1873-74.

The Trap-door Spider (_Mygale henzii_, Girard), which is widely
diffused in California, forms a simple shaft-like burrow, but, like
the European Trap-door Spider, it is very skilful in forming an entrance
and in concealing its presence. Its habits have lately been described
by D. Cleveland of San Diego.[84] In the adobe land hillocks are
numerous; they are about a foot in height, and some three or four feet
in diameter. These hillocks are selected by the spiders--apparently
because they afford excellent drainage, and cannot be washed away by
the winter rains--and their stony summits are often full of spiders'
nests. These subterranean dwellings are shafts sunk vertically in the
earth, except where some stony obstruction compels the miner to
deflect from a downward course. The shafts are from five to twelve
inches in depth, and from one-half to one and a half inches in
diameter, depending