On the Homology of certain elements in the Skull of Bufo regularis Reuss (Salientia).

S ummary . A centre of ossification is described for the first time in the auditory region of Bufo regularis Reuss. A similar one is present in Calyptocephalus gayi (Reinbach, 1939), where it was identified as “supratemporal”. This centre has been homologized here with the postfrontal bone present in Apoda and in the Miobatrachidae. Since the postfrontal of one side fuses with the corresponding squamosal towards the end of metamorphosis, the name “postfronto‐squamosal” is introduced. The development of the so‐called fronto‐parietal is followed in three species of Salientia, which were not examined by Eaton. It is found that this bone develops from one centre of ossification in all cases. After comparison with fossil forms it is concluded that it must be regarded as a frontal only.