Pyx, the name of a cup-shaped, gold-lined vessel, with lid, used in the Roman Catholic churches for containing the eucharistic elements after their consecration either for adoration in the churches or for conveying to sick-rooms. Pyx means “box.” Hence Trial of the Pyx is the annual test of the British coinage, for which purpose one coin in every 15 lbs. of gold and one in every 60 lbs. of silver coined is set aside in a pyx or box.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Pythoness * Quadragesima