slender as rushes, and with limbs like hairs, can catch and kill the fry
of the smaller fishes. Most of these are like divers, who have to provide
themselves with air to breathe, and work at double speed in addition.

If a group of whirligig beetles is disturbed, the whole party will dive
like dabchicks, rising to the surface again when they feel the need for
breathing-air again. The diving-bell spiders, which do not often frequent
the main Thames stream, though they are commonly found in the ditches near
it, gather air to use just as a soldier might draw water and dispose it
about his person in water-bottles. They do this in two ways, one of which
is characteristic of many of the creatures which live both in and out of
the water as the spider does. The tail of the spider is covered with
black, velvety hair. Putting its tail out of the water, it collects much
air in the interstices of the velvet. It then descends, when all this air,
drawn down beneath the surface, collects into a single bubble, covering
its tail and breathing holes like a coat of quicksilver. This supply the
spider uses up when at work below, until it dwindles to a single speck,
when it once more ascends and collects a fresh store. The writer has seen
one of these spiders spin so many webs across the stems of water plants in
a limited space that not only the small water-shrimps and larvae, but even
a young fish were entangled. The other and more artistic means of
gathering air employed by the spider is to catch a bubble on the surface
and swim down below with it. The bubble is then let go into a bell woven
under some plant, into which many other bubbles have been drawn. In this
diving-bell the eggs are laid and the young hatched, under the constant
watch of the old spider. Few people care to take the trouble to gaze for
any time into a shallow, still piece of water, in which the bottom is
plainly discernible, and a crop of water-weeds makes a wall on either side
of some central "well." If they do find some such pond near the Thames
banks or a shallow backwater, they may see after a few minutes much that