ion, where it falls in the way
of any naturalist to make his remarks. This I have often taken notice
of, that several holes of different depths are left unfinished at the end
of summer. To imagine that these beginnings were intentionally made in
order to be in the greater forwardness for next spring, is allowing
perhaps too much foresight and _rerum prudentia_ to a simple bird. May
not the cause of these _latebroe_ being left unfinished arise from their
meeting in those places with strata too harsh, hard, and solid, for their
purpose, which they relinquish, and go to a fresh spot that works more
freely? Or may they not in other places fall in with a soil as much too
loose and mouldering, liable to flounder, and threatening to overwhelm
them and their labours?

One thing is remarkable--that, after some years, the old holes are
forsaken and new ones bored; perhaps because the old habitations grow
foul and fetid from long use, or because they may so abound with fleas as
to become untenantable. This species of swallow, moreover, is strangely
annoyed with fleas; and we have seen fleas, bed-fleas (_pulex irritans_),
swarming at the mouths of these holes, like bees on the stools of their
hives.

The following circumstance should by no means be omitted--that these
birds do not make use of their caverns by way of hybernacula, as might be
expected; since banks so perforated have been dug out with care in the
winter, when nothing was found but empty nests.

The sand-martin arrives much about the same time with the swallow, and
lays, as she does, from four to six white eggs. But as this species is
cryptogame, carrying on the business of nidification, incubation, and the
support of its young in the dark, it would not be so easy to ascertain
the time of breeding, were it not for the coming forth of the broods,
which appear much about the time, or rather somewhat earlier than those
of the swallow. The nestlings are supported in common like those of
their congeners, with gnats and other small insects, and sometimes they
are fed with _libelluloe_ (dragon-flies) almost as long as themselves. In
the last week in June we have seen a row of these sitting on a rail near
a great pool as perchers, and so young and helpless, as easily to be
taken by hand; but whether the dams ever feed them on the wing, as
swallows and house-martins do, we have never yet been able to determine,
nor do we know whether they pursue and attack birds of pr