The systematic visitation of such religious houses in England as were not exempt from the jurisdiction of the Ordinary began, as is well known, soon after the Fourth Lateran Council of 1215. Prior to this, visitation by those of their own habit was unknown among the black monks and black canons, and the right and duty of the diocesan to visit, though it was an ancient practice sanctioned by early canons and decretals, was in fact rarely exercised in this country before the pontificate of Innocent III. In contrast to this, among the new orders, such as the Cistercians and the Pre-monstratensians, regular visitation had from the first been an integral part of their constitution. They were, however, exempt from episcopal surveillance, and therefore experienced no change in the thirteenth century. For the two older bodies, still the most numerous in England, the black monks and the black canons, together with the nuns who followed their Rules, the years immediately after the Council saw the opening of two series of visitations: the triennial visitation by two religious of their own habit appointed in provincial chapter, and the less regular visitation by the diocesan undertaken in the course of his periodical tours through the diocese. In addition, the regulars who did not depend immediately upon the Apostolic See were liable from the middle of the century onwards to receive a call from the archbishop of Canterbury when he visited the dioceses of his suffragans.