The family of Short-winged Birds which is represented by the Ostrich,
differs so greatly from all the other long-legged Birds that some
Naturalists include them in a separate group, and call them Cursores or
Runners. This is an arrangement that has much in its favor, but they
seem to be more popularly grouped with the great order of Long-legged or
Wading Birds.
All the Birds in this family have wings, but so slightly developed that
they are entirely unfit for purposes of flight, and are only useful in
increasing the speed of their limbs. Their legs are very long and
powerful and capable of immense muscular effort, thus enabling them to
run with extraordinary fleetness.
This group includes the Ostrich, Emu, Rhea, Cassowary and the Apteryx.