houses on piles of mud which rise
out of the water. These houses are usually made of heaps of dead grass
and weeds which are cemented together with mud and clay; at other times
they contain no mud or clay, and seem to be only piles of tender roots
and swamp grasses to be used for food during the long, cold winters.

From his physical appearance, the muskrat is well prepared to do his
work: he is stoutly built, with a body about a foot in length, not
including the tail; has small eyes, and tiny ears, partly covered with
fur. In the winter, as food gets scarce, he begins to eat even the
walls of his house, and by the time his home is gone--spring has
arrived!

A most unusual family of skilled house-builders are the brush-tailed
rat-kangaroos, or Jerboa kangaroos of Australia and Tasmania. They are
no larger than an ordinary rabbit, but they have cousins who are as
large as a man. These rat-kangaroos have most interesting tails, covered
with long hair which forms itself into a crest near the tip. Their homes
are found among small grassy hills, where there are a few trees and
bushes. They scratch out a small hole in the ground, near a tuft of tall
grass, and so bend the grass as to form a complete roof to the house,
which is rather poorly constructed, and whose chief interest lies in the
unusual way the kangaroos have of carrying all the building materials,
like tiny bundles of hay, held compactly in their tails. There is no
other workman among the animals that employs quite this method of
transporting materials.

The rat-kangaroos have a dainty little brown cousin that lives in
Africa, and who is occasionally seen jumping around on the ground,
underneath bushes, and near damp springs. He is very small, not over
three inches in length, and is like a miniature kangaroo, except for his
long tail. Like their great cousins--the kangaroos--Mrs. Jerboa often
carries her babies on her back when she goes out to seek food.

In the Great Sahara Desert, parched and dry, are found numerous cities
of these little animals. With the exception of a few birds, reptiles,
jackals and hyenas, they are the only inhabitants of this barren and
desolate land. From the Arabs we learn that these little animals have
extensive and intricate burrows, consisting of innumerable passages
tunnelled out in the hard, dry soil. And these tunnels are the result of
combined labour on the part of the entire community. The least alarm
causes them to scuffle