Osteopilus is a genus of frogs in the Hylidae family. These species have a bony co-ossification on the skull resulting in a casque, hence its name ‘bone-cap’, from osteo- (‘bone’) and the Greek pilos (πῖλος, ‘felt cap’). Color varies between uniform brown, brown-gray, or olive with darker markings or marbled with greens, grays or brown, making a distinct pattern. The finger disks are round; the fingers with a reduced webbing; eyes and tympanum are large. Their natural range includes the Greater Antilles and the Bahamas, but O. septentrionalis has also been introduced to the Lesser Antilles, Hawaii and Florida (USA).