Quadrans n. : A fourth part of the coin called an as. See 3d As, 2.

Quadrans n. : The fourth of a penny; a farthing. See Cur.

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Taxonomy
Quadrans Muralis, coin, pellets, free encyclopedia, Search, Ancient Rome, cast, bust, prow, bronze coins, constellation, Apulia, Antoninus Pius, Roman coin, 270 BC, 220 BC, Casting, metalworking.

Defination from the web:
quadrans was issued from the beginning of cast bronze coins during the Roman Republic with three pellets representing three unciae as a mark of value. ... 90 BC, when bronze coinage was reduced to the semuncial standard, the quadrans became the lowest-valued coin in production. ...