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 XIII

Canon XIII.

That a bishop should not be ordained except by many bishops, but if there should be necessity he may be ordained by three.

Bishop Aurelius said:  What says your holiness on this matter?  By all the bishops it was answered:  The decrees of the ancients must be observed by us, to wit, that without the consent of the Primate of any province even many bishops assembled together should not lightly presume to ordain a bishop.  But should there be a necessity, at his bidding, three bishops should ordain him in any place they happen to be, and if anyone contrary to his profession and subscription shall come into any place he shall thereby deprive himself of his honour.

Notes.

Ancient Epitome of Canon XIII.

At the bidding of the Primate even three bishops can make a bishop.  But whoever goes counter to his profession, and subscription, is deprived of his honour by his own judgment.

This is Canon xij. of the before mentioned Synod of 387 or 390.

Johnson.

See Can. Ap. 1, Nic. 1.

He that was called a Metropolitan in other Churches was a Primate in Africa.