Each civitas had a number of decuriae assigned to it as an indication of its size .
Jump up ^ Decuriae was a Roman term used by Elder Pliny in his Natural History completed in 70 AD based on official registers .
Each civitas had a number of decuriae assigned to it as an indication of Roman 's size .
Jump up ^ Decuriae was a Roman term used by Elder Pliny in his Natural History completed in 70 AD based on official registers .