LAST year, a note was published in Nature1 which summarized the recommendations of an international colloquium at Luxemburg on the definition of Jurassic stages and added the views of the British Mesozoic Committee on these recommendations. The stated object of this note was to give other British Mesozoic specialists the opportunity of considering the recommendations and of expressing their opinions about them. As a result of this and of further recommendations from other national committees brought forward at a meeting of the international Mediterranean Mesozoic Committee in September 1963, the British Committee decided that further discussions were necessary. A general meeting was, therefore, arranged at the Geological Society of London on February 26. This meeting, which was attended by 65 geologists who were specializing in the Mesozoic, was intended to guide the Committee in framing its further recommendations to the international organization.