Development of the Dermal Bones in the Skull of Lepidosteus Osseus

Abstract

1. The development of the dermal elements of the skull of Lepidosteus osseus has been studied in a series of twelve stages. 2. The homologies of the three small scale-bones of the snout have been established. They are the rostral, nasals, and antorbitals. 3. The ‘maxillary chain’ is shown to be an extension of the infra-orbital series, and the existence of a true maxillary is established. 4. The extent and single origin of the premaxillary are shown, and its unusual association with the supra-orbital basal is discussed. 5. The correct homologies of the opercular series have been established, the recognition of a sub-orbital has been recorded. 6. It is shown that Stensio's complex nomenclature is redundant to a description of the dermal bones of the skull of Lepidosteus osseus.