I. American genera. _A._ The metasternum forms a cartilaginous plate without a narrow handle. The pupil contracts into a horizontal slit. _a._ The terminal phalanges are bifurcated, Y-shaped, and provided with large discs; the tympanum is distinct; the omosternum is absent .......... _Centrolene geckoideum_, Ecuador. {212}_b._ The terminal phalanges are T-shaped and carry discs. The omosternum is cartilaginous. α. Discs divided by a dorsal groove. With vomerine teeth .......... _Elosia_, 3 species in Brazil. Without " .......... _Syrrhopus_,[91] 9 species, South America. β. Discs undivided. With vomerine teeth .......... _Hylodes_, p. 214. Without " .......... _Hylopsis._ _c._ Terminal phalanges simple, pointed, or with very small discs. First finger opposed to the others .......... _Pseudis_, p. 213. _d._ Terminal phalanges simple, without discs. α. Tympanum hidden. A large, flat gland on each side of the body .......... _Cyclorhamphus fuliginosus_, Brazil. β. Tympanum distinct. Head rough, entirely bony. .......... _Calyptocephalus_, p. 215. γ. Tympanum hidden or absent. Tongue roundish, not nicked, free behind. Toes webbed. .......... _Telmatobius_, 6 species in Western South America. δ. Tongue heart-shaped, free. Toes webbed. .......... _Ceratophrys_, p. 215. ε. Tongue round, free behind. Toes webbed. With two tooth-like projections in the lower jaw. .......... _Lepidobatrachus_, p. 218. ζ. Tongue entire, or slightly nicked, free behind. Toes free. .......... _Borborocoetes_, 11 species in Western South America. η Tongue entirely adherent Tympanum distinct. .......... _Zachaenus parvulus_, Brazil. _B._ Metasternum with a bony style. _a._ Pupil horizontal α. Terminal phalanges T-shaped, with discs. Tympanum distinct. .......... _Plectromantis_, 2 species in Western South America. β. Terminal phalanges simple; tips not dilated into regular discs. 1. Tympanum distinct. Sacral diapophyses slightly dilated. .......... _Edalorhina_, 3 species in Ecuador and Peru. Sacral diapophyses not dilated. .......... _Leptodactylus_, p. 218. 2. Tympanum indistinct or hidden, _Paludicola_, p. 220. _b._ Pupil vertical. Terminal phalanges simple and not dilated. Chili. α. Tongue slightly nicked .......... _Limnomedusa macroglossa._ β. Tongue entire, but free behind. Digits very long. .......... _Hylorhina silvatica._ II. Australian genera. The terminal phalanges are simple and not dilated. The omosternum and metasternum are cartilaginous, the latter forming a plate, semi-ossified only in _Heleioporus_.