Reference edition:

Q. Aurelii Symmachi quae supersunt, edidit O. Seeck, Berolini 1883 (Monumenta Germaniae Historica, Auctores Antiquissimi VI, 1).

The fragments of Q. Aurelius Symmachus, despite being of an oratorical nature, are distinct from the Orations edited by Otto Seeck; consequently, they are instead collected in the first part of the sixth volume of the Monumenta Germaniae Historica.  The fragments consist of the following: 1) two passages cited by Arusianus Messius, which were excerpted from a discourse - presumably famous - addressed to the emperor Theodosius (and therefore dating to the final years of Symmachus’ life, as distinct from the Orations, which date to the first phase of his political career in the senate); 2) an excerptum contained in one of Symmachus’ letters (4.28), which Seeck connects to an Oratio de censura non restituenda; and 3) a few lapidary sententiae - fully in keeping with Symmachus’ style - that are reported by authors like Cassiodorus (who calls him facundissimus) and Sidonius Apollinaris.  [V. Del Core; tr. C. L. Caterine].