The question of the zonal division of the Carboniferous system has been raised during the last twelve months, and certain fossils have already been mentioned as typical of a certain succession in a certain district or traverse of rocks. Having studied the Carboniferous system in most of the districts of Great Britain and Ireland where the beds are exposed, and chiefly from a palæontological point of view, I beg to offer for discussion a few of the facts of biological distribution which have come to my knowledge.