Molossidae, or Free-tailed bats, are a family of bats within the Chiroptera order. They are generally quite robust, and consist
of many strong flying forms with relatively long and narrow wings. Another common name for some members of this group, and
indeed a few species from other families, is Mastiff Bat. The Western mastiff bat, Eumops perotis, a large species from the
southwestern United States and Mexico with wings over half a metre across, is perhaps one of the best known with this name.