This frog is the largest in North America and is distinguished by lacking dorsolateral folds and having very large tympanums, larger than the eye in males. The tips of the fingers and toes are blunt. The webbing is well developed. The skin on the back of this species is rough with random tiny tubercles. There is no dorsolateral fold, but there is a prominent supratympanic fold. The mean snout to vent length for males is 152 mm (range 111-178) and for females it is 162 mm (range 120-183). The males have pigmented nuptial pads. The vocal openings are at the corner of the mouth.The dorsum is green, with or without a netlike pattern of gray or brown on top. The venter is slightly white, sometimes mottled with gray or yellow. Coloration varies widely depending on the locality of the bullfrog (Conant and Collins 1975).
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