d eel-like wrigglings of
the muscular tail. It would have seemed like no more than a darker,
swiftly-moving shadow in the dark water, save for a curious burden of
air-bubbles which went with it. Its close under-fur, which the water
could not penetrate, was thickly sprinkled with longer hairs, which
the water seemed, as it were, to plaster down; and under these long
hairs the air was caught in little silvery bubbles, which made the
swimmer conspicuous even under two inches of clear ice and eighteen
inches of running water.

As he went, the swimmer slanted downward and aimed for a round hole at
the bottom of the bank. This hole was the water-gate of his winter
citadel; and he, the keeper of it, was the biggest and pluckiest
muskrat on the whole slow-winding length of Bitter Creek.

At this point Bitter Creek was about four feet deep and ten or twelve
feet wide, with low, bushy shores subject to overflow at the slightest
freshet. Winter, setting in suddenly with fierce frost, had caught it
while its sluggish waters were still so high from the late autumn
rains that the bushes and border grasses were all awash. Now the young
ice, transparent and elastic, held them in firm fetters. The flat
world of field and wood about Bitter Creek was frozen as hard as iron,
and a biting gale, which carried a thin drift of dry, gritty snow, was
lashing it pitilessly. The branches snapped and creaked under the
cruel assault, and not a bird or beast was so hardy as to show its
head abroad. But in the muskrat's world, there under the safe ice, all
was as tranquil as a May morning. The long green and brown water-weeds
swayed softly in the faint current, with here and there a silvery
young chub or an olive-brown sucker feeding lazily among them. Under
the projecting roots lurked water-snails, and small, black, scurrying
beetles, and big-eyed, horn-jawed larvae which would change next spring
to aerial forms of radiance. And not one of them, muskrat, chub, or
larva, cared one whit for the scourge of winter on the bleak world
above the ice.

The big muskrat swam straight to the mouth of the hole, and plunged
half-way into it. Then he suddenly changed his mind. Backing out
abruptly, he darted up to the surface close under the edge of the
bank. Along the edge of the bank the ice-roof slanted upward, the
water having fallen several inches since the ice had set. This left a
covered air space, about two inches in height, all along the fringes
of th