What is Antiqua Custuma?

Legal Definition
In English law. Ancient custom. An export duty on wool, wool-felts, and leather, imposed during the reign of Edw. I. It was so called by way of distinction from an increased duty on the same articles, payable by foreign merchants, which was imposed at a later period of the same reign and was called "custuma nova." 1 Bl. Comm. 314.
-- Black's Law Dictionary
Legal Definition
Certain statutory duties on wool and leather.
-- Ballentine's Law Dictionary