The genus is characterized by well-developed dermal roofing bones and an unusually large exposure of the sphenethmoid dorsally (Fig. 6). The conformation of the sphenethmoid exposed dorsally is determined by the marginal positions of the adjacent, overlapping elements--the nasals and frontoparietals. Medially the nasals overlap the lateral margins of the sphenethmoid. Anteromedially, the nasals converge in _leprieurii_ and _taurinus_, are narrowly separated in _buckleyi_ and _pearsoni_, or are more widely separated in _verrucigerus_. In all species the nasals terminate at the anterodorsal corner of the orbit. The frontoparietals of _buckleyi_, _leprieurii_, and _taurinus_ have an anterolateral extension, which marginally overlaps the dorsolateral edge of the sphenethmoid and articulates with the posterodorsal corner of the nasal in _buckleyi_ and _taurinus_; the bones are narrowly separated in _leprieurii_. The frontoparietals of _pearsoni_ and _verrucigerus_ have more extensive median ossification and less extensive anterolateral ossification. Thus, in those species the posteromedian portion of the sphenethmoid is obscured, and the lateral margins are partly exposed. The frontoparietal fontanelle is completely covered in all species, except _buckleyi_ and _leprieurii_, in which an irregular, median separation of the frontoparietals exposes a small portion of the fontanelle. The posterolateral margins of the frontoparietals lie medial to the epiotic eminences. Dermal ornamentation, involving the nasals, frontoparietals, and sphenethmoid, occurs in _taurinus_ and, to a limited extent, in _pearsoni_. In the latter species marginal portions of the frontoparietals, the dorsal surfaces of the nasals, and the posteromedial part of the exposed sphenethmoid are slightly exostosed, resulting in an open, reticulate pattern of dermal sculpturing of exceedingly low relief (Fig. 6c). _Osteocephalus taurinus_ is characterized by casquing, co-ossification, and a rather intricate pattern of dermal sculpturing, which was described in detail and illustrated by Trueb (1970a). The squamosals of all species are moderately large structures having otic plates that overlie the lateral portion of the cristae paroticae. The posterior rami are short; the zygomatic rami of all species, except _taurinus_, extend slightly more than one-half of the distance to the maxillary. In _taurinus_ the zygomatic ramus extends nearly to, or articulates with, the maxillary.