American Bullfrog

They grow on average to be about 3.6 to 6 in (9.1 to 15 cm) in body length (although there are records of some up to 8.0 in (20 cm)), legs add another 7 to 10 in (18 to 25 cm) to length. The adult bullfrog skeleton is representative of tetrapod vertebrates, comprising an axial skeleton (skull and vertebrae) and an appendicular skeleton (pectoral girdle and forelimbs, pelvic girdle and hindlimbs). Ranids, however, lack ribs. The pronounced pair of dorsal humps in the back of ranid frogs are the ends of the pelvic ilia, homologues of the human hips.
The bullfrog skull is highly fenestrated. The orbits open ventrally through the roof of the mouth to accommodate eye retraction during locomotion and swallowing. The skull bears a continuous row of tiny teeth on the maxilla and premaxilla and a pair of small vomerine teeth on the palate. The mandible is toothless.
The bullfrog nervous system consists of a brain, spinal cord, and peripheral nerves, including cranial, spinal, and sympathetic nerves serving organs, such as the heart, gastrointestinal tract, kidneys, and gonads.
Females have eardrums (tympana) the same size as their eyes. Males' eardrums are larger. Largest in North America. Green-yellow with dark gray mottling. External eardrum large. Webbed hind feet except largest toe. Underside white with gray mottling. Darker markings on hind legs.