Nicene and Post-Nicene Fathers, Ser. II, Vol. XIV:
The Canons of the Councils of Ancyra, Gangra, Neocæsarea, Antioch and Laodicea, which Canons were Accepted and Received by the Ecumenical Synods.: Canon LVII

Canon LVII.

Bishops must not be appointed in villages or country districts, but visitors; and those who have been already appointed must do nothing without the consent of the bishop of the city.  Presbyters, in like manner, must do nothing without the consent of the bishop.

Notes.

Ancient Epitome of Canon LVII.

A bishop shall not be established in a village or in the country, but a periodeutes.  But should one be appointed he shall not perform any function without the bishop of the city.

On the whole subject of Chorepiscopi see the Excursus to Canon VIII. of Nice, in this volume.

Hefele.

Compare the eighth and tenth canons of the Synod of Antioch of 341, the thirteenth of the Synod of Ancyra, and the second clause of the sixth canon of the Synod of Sardica.  The above canon orders that from henceforth, in the place of the rural bishops, priests of higher rank shall act as visitors of the country dioceses and country clergy.  Dionysius Exiguus, Isidore, the Greek commentators, Van Espen, Remi Ceillier, Neander, and others thus interpret this canon; but Herbst, in the Tübingen Review, translates the word (περιοδευταί ) not visitors but physicians—physicians of the soul,—and for this he appeals to passages from the Fathers of the Church collected by Suicer in his Thesaurus.

This canon is found in the Corpus Juris Canonici, Gratian’s Decretum, Pars I., Dist. LXXX., c. v.