Nicene and Post-Nicene Fathers, Ser. II, Vol. XIV:
The Canons of the Synods of Sardica, Carthage, Constantinople, and Carthage Under St. Cyprian, Which Canons Were Received by the Council in Trullo and Ratified by II. Nice.: Canon LXXXV

Canon LXXXV.  (Greek lxxxviii.)

That by the bishop of Carthage, when there shall be need, letters shall be written and subscribed in the name of all the bishops.

It was said by all the bishops:  If any letters are to be composed in the name of the council it seemed good that the venerable bishop who presides over this See should vouchsafe to dictate and sign them in the name of all, among which also are those to the episcopal legates, who are to be sent throughout the African provinces, in the matter of the Donatists; and it seemed good that the letters given them should contain the tenor of the mandate which they are not to go beyond.  And they subscribed:  I, Aurelius, bishop of the church of Carthage have consented to this decree and having read it have signed it.  Likewise all the rest of the bishops subscribed.

Notes.

Ancient Epitome of Canon LXXXV.

It seemed good that whatever letters were to be sent from the Synod should be written and subscribed by the bishop of Carthage in the name of all.

This is Canon xix. of Carthage, September, a.d. 401.

In this Council previous decrees are confirmed.

In the fifth consulate of the most glorious Emperors Arcadius and Honorius, Augusti, the VI Calends of September, in the City of Milevis, in the secretarium of the basilica, when Aurelius the bishop of Carthage had taken his seat in plenary council, the deacons standing by, Aurelius, the bishop, said:  Since the body of the holy Church is one, and there is one head of all the members, it has come to pass by the divine permission and assistance given to our weakness, that we, invited out of brotherly love, have come to this church.  Wherefore I beg your charity to believe that our coming to you is neither superfluous, nor unacceptable to all; and that the consent of all of us may make it manifest that we agree with the decrees already confirmed by the Council at Hippo or which were defined afterwards by a larger synod at Carthage, these shall now be read to us in order.  Then at last the agreement of your holiness will appear clearer than light, if they know that the things lawfully defined by us in former councils, ye have set forth, not only by your consent to these acts, but also by your subscriptions.

Xantippus, bishop of the first see of Numidia said:  I believe what pleased all the brethren and the statutes they confirmed with their hands; we by our subscribing our names shew that it pleases us also, and have confirmed them with our superscription.

Nicetius, the bishop of the first see of Mauritania Sitifensis said:  The decrees which have been read, since they do not lack reason, and have been approved by all, these also are pleasing to my littleness, and I will confirm them with my subscription.