MOST workers on fossils at the present day try to conform to the International Rules of Zoological Nomenclature,1 but there are cases in which even the most conscientious palaeontologist may be in doubt as to whether any given article or recommendation of the International Code can justifiably be applied. Some workers, I may add, are forgetting that this code should be a good servant, and must not be allowed to become a bad master; again, while others are in favour of applying to the International Commission for standardization of almost every problem, many palaeontologists feel that the rules should not be relaxed except in very special cases. It seems to me of general interest to discuss some doubtful cases; for future workers may be guided by our difficulties, and the overworked Commission will eventually benefit by the discussion.