In the Geological Magazine for July and August last Mr. A. J. Jukes-Browne made a proposal for the recognition in England, France, and Germany of a boundary-line between two corresponding stages in the middle of the old zone of Actinocamax quadratus. The reception to be given to this proposal so far as it concerns France and Germany must be a matter for the geologists of those countries, and I am concerning myself chiefly with the proposal as it affects the English Chalk. Inasmuch as I sympathize with the proposal, and my own work is partly relied upon, it may seem ungracious in me to criticize it, but there are several points on which criticism seems desirable if only to afford Mr. Jukes-Browne an opportunity of replying while the subject is still fresh.