The term Genus Gastrophryne applies to a group of small frogs belonging to the family Microhylidae. They are commonly referred to as narrow-mouthed toads. The Genus Gastrophryne consists of just six species which are endemic to North America. These species include the plains narrow-mouthed toad, Great Plains narrow-mouthed toad, Mexican narrow-mouthed toad, Cajun narrow-mouthed toad, canyon narrow-mouthed toad, and eastern narrow-mouthed toad. All of these species are tiny, measuring only up to 4cm in length. Alternatives to Genus Gastrophryne include the more general classification of narrow-mouthed frogs or the specific names of each of the six species of Gastrophryne.