{224}_Hylopsis platycephalus_, of South America, is of importance as forming a link with the Dendrophryniscinae, owing to the very small size of the teeth in the upper jaw. There are no vomerine teeth. The fingers and toes are webbed, and furnished with discs. The very small omosternum and the metasternum are cartilaginous. The pupil is horizontal. Total length, about or under 1½ inch. SUB-FAM. 3. DENDROPHRYNISCINAE.–The two Neotropical genera of this sub-family are characterised by the entire absence of teeth. The toothless condition of the upper jaw is really the sole character which separates them from the Cystignathinae, taken as a whole. The suppression of the tympanum and of the Eustachian tubes in _Batrachophrynus_, and the fully webbed toes of _B. macrostomus_ indicate complete adaptation to aquatic life. The absence of the omosternum in _Dendrophryniscus_, the absence of vomerine teeth, the dilated phalangeal tips, the entire and quite adherent tongue, are all features which likewise occur in some of the Cystignathinae, and therefore cannot be urged against their affinity. Lastly, the recently discovered South American genus _Hylopsis_ is, as pointed out by Werner,[98] an intermediate link, owing to the extremely small, scarcely visible teeth in the upper jaw. _Dendrophryniscus brevipollicatus_ has been found in the neighbourhood of Rio Janeiro. The head is depressed and triangular. The tongue is entire, but free behind. The tympanum is suppressed. The omosternum is absent; the metasternum forms a long bony style. The sacral diapophyses are cylindrical. The terminal phalanges are simple, but carry dilated tips. The first finger is rudimentary. The skin is nearly smooth, reddish brown above, whitish below; the limbs are cross-barred. _Batrachophrynus_ inhabits the mountains of Peru. The head is much depressed and small, with the eyes directed upwards, as is usual in essentially aquatic species. The tongue is large, circular, and entirely adherent. The tympanum and the Eustachian tubes are suppressed. The omosternum is cartilaginous, and the metasternum forms a cartilaginous plate. The sacral diapophyses are cylindrical. The terminal phalanges are simple, and carry no discs. The four fingers are short; the toes are webbed. The male has no vocal sac. _B. brachydactylus_ has a {225}smooth skin, olive-brown above with darker spots. _B. macrostomus_, 2 inches in length, is distinguished by its larger size, and by its completely webbed toes. FAM. 6. ENGYSTOMATIDAE (Narrow-mouthed Toads).–_Firmisternia with dilated sacral diapophyses._