The Tabula Peutingeriana indicates that, from Agen, the Roman road went to Excisum, from Excisum to Diolindum and from Diolindum to Divona/Cahors. All four places seem to be placed in a line as if situated on the same river, which they aren’t. Toulouse is placed somewhere between Bordeaux and Agen, whereas from Agen it is about the same distance as Bordeaux – but in the opposite direction – Agen equidistant from the two.
It’s clear, as described before, that the section of the map covering modern Brittany should be swivelled clockwise about 90º. Now, take the section showing Tolosa, Aginnum, Excisum and Diolindum, leading to Divona (Cahors):
If this is twisted round anti-clockwise 135º, we have Toulouse in its correct position in relation to Agen, while Excisum and Diolindum lead to Vesunna (Périgueux) rather than Cahors – just as the Itinerary has Agen, Excisum, Traiectus, Vesunna.
Absurd, though, to manœuvre a small pencil of land into the desired position and leave its surroundings untouched. What kind of mistake could explain that?
But … Just One More Thing.
Looking at the figures after the placenames: XIII indicates the distance from Aginnum to Excisum, exactly the same as the distance given in the Itinerary. No mystery there because there’s no argument that Excisum was Eysses so they are recording the identical journey. Something more of a coincidence is that Excisum to Diolindum is XXI (enhanced this is quite clear and accepted by the authorities). This is exactly the same as Excisum to Traiectus in the Itinerary. Then Diolindum to Cahors is XXIIII. Annoyingly, Traiectus to Vesunna/Périgueux is XVIIII. Doubly annoying because XXIIII could so easily have been misread as XVIIII – or vice versa.¹ But it’s weak evidence that is based on, ‘Yes, but perhaps someone made a mistake there’.
But my money is still on Diolindum and Traiectus being at roughly the same place on the Dordogne.
Probably time now to move on from Aquitaine and scour the Itinerary for other examples of the placename Traiectus.
¹ In fact, if the Itinerary’s XVIIII was a misreading for XXIIII, the distance between Traiectus/Lalinde and Vesunna would be much more accurate (‘as the crow flies’ 26 Roman miles rather than 18) .