_Remarks._--_Phyllomedusa_ includes 1) a series of large species (_bicolor-burmeisteri_) showing progressive specialization of the feet; 2) a series of small species having grasping feet (_ayeaye_, _centralis_, _cochranae_, _guttata_, _hypochondrialis_, and _rohdei_); 3) a series of small, relatively unspecialized species (_lemur_, _loris_, and _medinae_); and 4) several other species of questionable affinities. Lutz (1966) resurrected Cope's (1866) _Pithecopus_ for 12 species (_ayeaye_, _boliviana_, _burmeisteri_, _coelestis_, _hypochondrialis_, _nicefori_, _rohdei_, _sauvagei_, _tarsius_, _tomopterna_, _trinitatis_, and _vaillanti_). Adequate material is not available for detailed study of all South American species; consequently, a firm classification cannot be established at this time. Nevertheless, it is obvious that Lutz's arrangement is unnatural. If subsequent investigations show, as seems likely, that the small specialized phyllomedusines are a natural phyletic unit, the generic name _Pithecopus_ is available. However, species such as _boliviana_, _burmeisteri_, _nicefori_, and _trinitatis_ do not belong in _Pithecopus_. As noted by Funkhouser (1962), the small, relatively unspecialized species (_lemur_, _loris_, and _medinae_) form a natural group; possibly this group should be accorded generic recognition. Until more evidence on the interspecific relationships is acquired, the maintenance of the current classification is desirable. DISCUSSION Noble (1931) considered the species of _Phyllomedusa_ having opposable digits, reduced terminal discs, and no webbing to be advanced and such species as _Agalychnis moreleti_, _calcarifer_, and _spurrelli_ to be primitive. Funkhouser (1957) followed Noble's suggestion and attempted to explain the evolution of the species of _Phyllomedusa_ (_sensu lato_) by assuming that they evolved from an advanced _Hyla_-like ancestor. Therefore, she placed those species having large, fully webbed hands and feet near the base of her phylogenetic scheme and hypothesized that evolutionary sequences involved stages of reduction and eventual loss of webbing, followed by the development of grasping toes. Such an evolutionary history is highly unlikely. The _Agalychnis_ phyletic line has one kind of specialization for an arboreal existence. It is contrary to evolutionary theory that a specialized group would evolve into a generalized form and then evolve new kinds of specializations to meet the needs imposed by the same environmental conditions affecting the earlier specialized group. A more reasonable hypothesis is that the evolution of opposable digits took place in a phyletic line that had as its ancestral stock a frog with generalized hands and feet. If this assumption is correct, _Phyllomedusa_ and _Agalychnis_ represent different phyletic lines; each exhibits divergent modes of adaptation for arboreal habits, whereas _Pachymedusa_ probably remains relatively