away into their underground homes.

One of the larger species of Central Asia employs a stratagem that is
remarkable. Like their cousins of Africa, they live in a great
underground city which is a perfect network of burrows which end in a
large central chamber. From this chamber a long winding tunnel
terminates very near the surface of the ground, and it is a long
distance from the other burrows. No sign of its existence appears from
above the surface of the earth, but if an enemy invades the burrow, away
the jerboas rush for this secret exit and break through to the surface
out of reach of the trouble, and escape.

These African jerboas are exceedingly odd in appearance, and they are
two-legged in their habits of walk, and never go on all-fours. They walk
by placing one hind foot alternately before the other; and they run in
the same way. They can leap an extraordinary distance.

Frogs and toads, as a class, are not so skilled in house-building as
some of their higher relations, but there is one of their number--the
_Hyla faber_--that is remarkably gifted in building mud houses. He lives
in Brazil, and the natives call him the _ferreiro_, or smith, and he is
indeed the master-builder of his family. Mrs. Hyla is really the gifted
member of the tribe, and it is during the breeding season that she
diligently dives underneath the water, digs up handfuls of mud, and
builds on the bottom a small circular wall, which encloses a space about
ten to fourteen inches in diameter. This wall is continued until it
reaches about four inches above the surface of the water. It looks not
unlike a small volcano, and the inside is skilfully smoothed. This has
been done by Mrs. Frog's artistic hands. When the house is entirely
completed, Mrs. Frog lays a great number of eggs, and here they are
quite safe from enemies both as eggs and baby tadpoles.

Mr. Frog seems little concerned in the building of the home, but he does
take pleasure in croaking for Mrs. Frog while she works. Perhaps this
is to her heart genuine music, and his faithful attention to their
children makes up for his love of idleness!

Perhaps the strangest animal engineer in the world is found in
Madagascar and Australia. It is the duckbill or duckmole, and is
scientifically known as the _Ornithorhynchus paradoxus_. The natives of
Australia call it by several names: _Mallangong_, _Tambreet_, and not a
few call it, _Tohunbuck_.

This odd little aquatic engineer digs long