A new genus and species,Scarthyla ostinodactyla, from the upper Amazon Basin in Peru is distinguished from other genera of Hylinae by cranial characters and the possession of ossified intercalary elements between the penultimate and terminal phalanges. The tadpoles develop in ponds but have long, muscular tails and low caudal fins, which are used in the unusual locomotion of propelling themselves at and above the surface of the water. Adults are small and have fully webbed feet by means of which they can leap from the surface of the water.