Note 51 — Chapter IV · PART I. THE AQUEDUCTS.
Reading edition
The manuscript called Codex Urbinas reads, jungitur ei ad anionem veterem. In the present instance, the true reading is evidently specum. Frontinus is describing the Aqua Appia, the oldest of the aqueducts, and the junction of the Augusta with the old specus. This could have nothing to do with the Anio Vetus.