the sticks and stones. Curled fresh-water snails moved up
and down the stems of the lilies. Shining little black water-bugs
scurried swiftly in all directions. In sheltered places near the
surface, under the leaves, wriggled the slim gray larvae of the
mosquitoes. And hither and thither, in flickering shoals, darted
myriads of baby minnows, from half an inch to an inch and a half in
length.

In a patch of vivid sunshine, about six inches from a tangle of
arrow-weed stems, a black tadpole lay basking. Light to him meant not
only growth, but life. Whenever, with the slow wheeling of the sun,
the shadow of a lily leaf moved over him, he wriggled impatiently
aside, and settled down again on the brightest part of the mud. Most
of the time he seemed to be asleep; but in reality he was keeping that
incessant sharp lookout which, for the pool-dwellers, was the price of
survival.

Swimming slowly up toward the other side of the arrow-weed stems, came
a fantastic-looking creature, something more than an inch and a half
in length. It had a long, tapering, ringed and armoured body, ending
in a spine; a thick, armoured thorax, with six legs attached; and a
large head, the back of which was almost covered by two big, dully
staring globes of eyes. The whole front of its head--part of the eyes,
and all the face--was covered by a smooth, cleft, shieldlike mask,
reaching well down under the breast, and giving the creature an
expression both mysterious and terrible. On its back, folded close and
obviously useless, were rigidly encased attempts at wings.

The little monster swam slowly by the motion of its long and strong
legs, thrusting out two short, hornlike antennae over the top of its
mask. It seemed to be eyeing a snail-shell on a stem above, and
waiting for the snail's soft body to emerge from the citadel; when on
a sudden, through the stems, it caught sight of the basking tadpole.
Instantly it became motionless, and sank, like a waterlogged twig, to
the level of the mud. It crept around, effacing itself against the
brown and greenish roots, till it was just opposite the quarry.
Then it sprang, propelling itself not only by its legs, but by the
violent ejection of a little stream of water from the powerful
breathing-valves near its tail.

The tadpole, as we have seen, was not asleep. With a convulsive
wriggle of its tail it darted away in a panic. It was itself no mean
swimmer, but it could not escape the darting terror that pu