Dictionary of National Biography, 1885-1900/Decuman
DECUMAN or DEGEMAN, Saint (d. 706?), a Welsh hermit, was, according to legend, born of noble parents in the south-west of Wales, and instructed in catholic, that is, perhaps, in Latin as opposed to Celtic doctrine. Wishing to escape from worldly companions he crossed the Severn sea (Bristol Channel) on a hurdle, and landed near Dunster Castle in Somerset (‘prope castrum Dorostorum’). There he became a hermit, and kept a cow, until he was slain by a murderer in 706. The place of his retirement and death is supposed to be commemorated by the name of the parish of St. Decumans, which includes the ancient borough of Watchet and the town of Williton. A chapel was dedicated to him at Wendron, Cornwall, and he is also the patron of Rosecrowther, Pembrokeshire, and of a chapel once standing in Llanfihangel Cwm Dû, Brecknockshire. The saint's well at St. Decumans was an object of veneration in the sixteenth century. His day is 27 Aug.
[Bolland. Acta SS. 27 Aug. 24, from Capgrave's Nova Legenda, fol. 85; R. Rees's Welsh Saints, 305; Haddan and Stubbs's Councils and Eccl. Docs. i. 161; Collinson's History of Somerset, iii. 486; Dict. of Christian Biog. i. 800.]