Abstract
Five species of Lunulitidae are described, all of which have been assigned in the past to a variety of genera, such as Lunulites, Otionella and Selenaria. None of the species seems to be certainly referable to any one of these genera, but several of them appear to be closely related to one another. At present no attempt is made to define any new generic group, or groups, for these species which are known, almost exclusively, from the Australian Tertiary deposits. The exception is Selenaria alata, a species originally described from the Miocene of Victoria, which has now been found in recent collections from the Bass Strait. The information these Recent specimens provide on the musculature and mandibular structure of the distinctive avicularia has considerable significance in interpreting the morphology and function of purely fossil species with similar skeletal characters.