Boulenger (1882) placed both _Osteocephalus_ and _Trachycephalus_ the synonymy of _Hyla_; he recognized _Hyla taurina_ (with _O. flavolineatus_ as a synonym), _H. leprieurii_, and _H. planiceps_. In the same publication Boulenger named _Hyla buckleyi_ on the basis of 10 specimens in the British Museum from Ecuador; in the description he stated that _buckleyi_ was like _leprieurii_ and _taurinus_ in having paired lateral vocal sacs. Boulenger held a lasting influence on taxonomic herpetology, and his generic synonymy of _Osteocephalus_ was unchallenged until only a decade ago. Goin (1961) presented a generic synopsis of the genera of hylid frogs, in which he recognized _Osteocephalus_ and stated: "There are perhaps eight or ten species of this genus in South America. Certainly _taurinus_, _britti_, _leprieuri_, _buckleyi_ and _pearsoni_ belong here. _O. planiceps_ is surely a synonym of _leprieuri_ and I believe that _garbei_ is as well. The status of such forms as _macrotis_, _riopastazae_, and _depressa_ has not yet been settled." Goin defined _Osteocephalus_ as follows: "Males with paired vocal pouches, one at each angle of the jaw; derm of head not co-ossified with skull but roof of skull exostosed." Trueb (1970a) elaborated on Goin's definition and assuredly included only _O. taurinus_ and _O. leprieurii_ in the genus. Goin's inclusion of _buckleyi_, _britti_, and _pearsoni_ in _Osteocephalus_ was the first association of any of these names with that genus. Duellman (1970a) demonstrated that _Garbeana garbei_ Miranda-Ribeiro, 1926, was a member of the _Hyla rubra_ group. _Hyla macrotis_ Andersson, 1945, is a _Phrynohyas_. Trueb and Duellman (1970) determined that _Hyla verrucigera_ Werner, 1901, is the earliest name for an _Osteocephalus_ displaying striking sexual dimorphism in coloration and texture of the dorsal skin; _Hyla riopastazae_ Andersson, 1945 (female holotype), and _Hyla orcesi_ Funkhouser, 1956 (male holotype), were placed in the synonymy of _Osteocephalus verrucigerus_. _Hyla pearsoni_ Gaige, 1929, is a small species of _Osteocephalus_. Our findings substantiate Goin's suggestions relative to two other taxa. _Hyla leprieurii britti_ Melin, 1941, from the Rio Uaupes, Brasil, and _Hyla depressa_ Andersson, 1945, from the Rio Pastaza watershed, Ecuador, are members of the genus _Osteocephalus_, but both are synonyms of earlier names--_leprieurii_ and _taurinus_, respectively. Another name proposed by Melin (1941), _Hyla (Trachycephalus) vilarsi_ from Taracua, Brasil, also is placed in the synonymy of _O. taurinus_.