τὸ πλῆθος οὐκ εὐαρίθμητον ἦν → the crowd wasn't easy to count, the crowd was not small, it was not a small crowd
ἐπιών, ἐπιοῡσα, ἐπιόν (AM)μτχ. ενέστ. του ρ. έπειμι.