Recent work on the development of the Dipnoi, ganoids, and amphibians, and the increase of our knowledge of the constitution of the stegocephalian and cotylosaurian skulls, throw much light on the interpretation and significance of the structure of the adult skull of Neoceratodus. That this was so very soon became apparent to me whilst engaged upon a general survey of the skull of Neoceratodus in connection with a paper on the evolution of the Anamniota and it was then decided to investigate the matter in more detail at a later date.
In the following pages I have recorded the observations made and the conclusions arrived at after comparing the various structures with those of the fishes and primitive tetrapods. This work has been made possible by the kindness of Dr. Thos. L. Bancroft, of Eidsvold, Queensland, who forwarded me three adult heads carefully preserved in alcohol; to him my thanks are tendered.
From one of these heads I have been fortunate in preparing a chondrocranium in a perfect state of preservation, denuded of every last scrap of tissue and of the investing bones, the latter being, of course, available for study as separate disarticulated bones.