The 51 species of
sac-winged or
sheath-tailed bats constitute the
family Emballonuridae, and can be found in
tropical and
subtropical regions all over the world. Emballonurids include some of the smallest of all bats, and range from 3.5 to 10 cm in body length. They are generally brown or grey, although the
ghost bats (genus
Diclidurus) are white.