Spanish physician, born at Frenegal, working in Llerena. The few biographical data known about Arcaeus are given in the introductory letter of Arias Montanus in the edition described below. Arias Montanus had met Arcaeus in Llerena in 1559-1560. At the time of the publication of the work, 1573-1574, the physician was 80 years old. Cf. Palau y Dulcet, 1, 1948, page 442.