In 1881 Mr. J. W. Davis proposed the genus Anodontacanthus for certain straight spines resembling Pleuracanthus, but differing in the absence of the two rows of denticles. Three species are included:–A. acutus and oltusus, from the Coal-measures of Yorkshire, and A. fastigiatus, from the Blackband Ironstone of Carboniferous Limestone age at Loanhead, near Edinburgh.