Fierce Bonneted Bat

This is the species of bat that Philip Henry Gosse referred to as the chestnut mastiff bat in his 1851 book, A Naturalist's Sojourn in Jamaica. Its ears are so large that they hang over its face. It has long, narrow wings. Like other members of its genus, it has a gular-thoracic gland, with the glands of the males producing a "very rank odour." Its ears are hairless, while its toes have long, bristly hairs. From head to tail, it is 131–151 mm (5.2–5.9 in). Its tail is 49–58 mm (1.9–2.3 in) long; its forearm is 57 mm (2.2 in) long. Individuals weigh approximately 38 g (1.3 oz).

It was described as a new species in 1861 by Cuban naturalist Juan Gundlach. Gundlach initially placed it in the genus Molossus, with the name Molossus ferox. It has been considered synonymous with Wagner's bonneted bat, Eumops glaucinus. It was generally recognized as synonymous with Wagner's bonneted bat until a 2008 study concluded that Wagner's bonneted bat was actually a species complex that should be broken into four species: Eumops ferox, the Florida bonneted bat, E. wilsoni, and Wagner's bonneted bat. Its species name "ferox" is of Latin origin meaning "ferocious" or "fierce." When handling an individual in Jamaica, Philip Henry Gosse remarked the following:

When handled, its impatience of confinement is manifested by a continuous screeching, not very loud, but excessivly harsh and shrill . . . The mouth also is then opened widely and threateningly, and a sufficiently grim armature of teeth developed.