Conic Form Research Articles

Discussions

Dr F. E. E ames said that Dr Adams had been kind enough to show him much of the material. The palaeontological material had consisted entirely of thin sections of hard limestones, and the speaker considered that, in the study of so many random sections of fossils, Dr Adams had shown commendable caution in the frequent use of 'sp.' and 'cf.' The speaker felt, however, that there might be some doubt about the identification of the genus Dictyoconus. None of the specimens Dr Adams had shown him had the characteristic features of the genus Dictyoconus : the high conic form, the distinctly coiled early portion with noticeable proloculus, and the well-developed two orders of partial partitions in the chambers of the outer cortical layer of the core. He hoped that the range of the genus would not be unequivocally extended up into the Oligocene on the basis of the occurrence of this species. The speaker understood that there was a tentative suggestion that a small thickness of beds in the Melinau section that immediately overlay richly num-mulitic Middle Oligocene (d stage) and underlay beds satisfactorily equated to the Indonesian e stage (lower part of Lower Miocene) were of Upper Oligocene age and should be included with the e stage. Some authors in the last few decades (e.g., van der Vlerk) had suggested that the Indonesian e stage was possibly of Chattian (Upper Oligocene) age in its lower part. Although it might have been thought, as a result of the speaker's own work,