Late Roman Unit Sizes

[Flavivs Aetivs]

"προσκουλκάτορας προσέταξεν ἄνδρας γενναίους ἐκ τοῦ ἀριθμοῦ τῶν λαγκιαρίων καὶ ματτιαρίων χιλίους πεντακοσίους"

"He set as scouts brave men from the arithmos of the lanciarii and the mattiarii 1,500"
13.21

Elizabeth Jeffreys et al. translate this as, "He . . . ordered the advance scouts to go ahead of them, 1500 valiant men from the numerus of the Lanciarii and Mattiarii."

The interesting thing about this is that arithmos and numerus are singulars. Does this mean that the Lanciarii and the Mattiarii had been combined into a single unit for this campaign?

Michael, my research indicates that both Palatine Legions and Auxiliary units could, and often were, brigaded together. And it was not always the same two units either, although in most most cases it was the same two. The Lanciarii and Mattiarii appear to be brigaded together during Julian's Sassanid campaign, as were the Herculanii and the Iovanii Legions. The Lanciarii and Mattiarii were brigaded together at Adrianople. The Auxiliary unit Batavia was generally brigaded with the auxiliary unit Heruli, but was also noted as being brigaded withe the Regii and also at least once with the Victories. We know that when the Batavia and the Heruli were brigaded together they shared the same standards. I'm not sure, nor convinced the legiones that were brigaded together would have done so.

So we have 2 numeri, one from each Legion, brigaded together and each numbers 750 men.

Knowing the Romans liked to round things, could this not have been 720 men each? That's easily divisible by 8 and a number the Romans liked to use.