The maxillary arches are complete and relatively robust. The alary processes of the premaxillaries are vertically oriented in _leprieurii_, _pearsoni_, and _taurinus_ and very slightly inclined posteriorly in _buckleyi_ and _verrucigerus_. The maxillaries are uniformly characterized by the absence of postorbital processes and by the presence of preorbital processes that articulate with the maxillary processes of the nasals. The partes facialae of the maxillaries are moderately developed in all species, except _taurinus_, in which the pars fascialis tends to articulate with the lateral margin of the nasal in well-ossified individuals. The partes palatinae are poorly developed in all species, except _buckleyi_, in which the pars palatina of the premaxillary is moderately robust. The pterygoids are uniformly tri-radiate structures. The anterior rami terminate at about the mid-level of the orbit, and the medial rami articulate firmly with the anterolateral corner of the otic capsule. The palatines are well-developed elements bearing ventral ridges; the ridges are somewhat irregular in _buckleyi_, _taurinus_, and _verrucigerus_ but smooth in _leprieurii_ and _pearsoni_. The parasphenoids are large elements characterized by acuminate cultriform processes and posterolaterally inclined alary processes. The basal areas of the cultriform processes bear small odontoid protuberances in _buckleyi_, _taurinus_, and _verrucigerus_, whereas they are smooth in _leprieurii_ and _pearsoni_. The prevomers are remarkably uniform, moderately well-developed structures. In each species the anterior ramus lies adjacent to the premaxillary, and the lateral wings form the anterior, medial, and posteromedial margins of the internal nares. The dentigerous processes are characteristically large and angular and bear numerous teeth. The sphenethmoid and otoccipitals are well ossified; a dermal sphenethmoid is present only in _taurinus_. [Illustration: FIG. 7. Dorsal views of vertebral columns of two species of _Osteocephalus_: a. _O. leprieurii_, KU 125962, [F]; b. _O. buckleyi_, USNM 165997, [F]. x2.]