Following Hontheim, Calmet and others, the Bollandists, with Marx, Aloys Lütolf, and other historians refer these bishops of Trier to a period following 250, though not all of them consider this as fully established.
Afterwards he led a party of 188 monks across the sea to Cornwall, where they were hospitably received by Mevor, a prince of the country, and Gudwal founded a monastery not far off (according to the Bollandists, in Devon).
John's life written by John of Seville towards the end of the fifteenth century with additions in 1605 and 1619, is the one used by the Bollandists in "Acta SS.", June, III, 112.
Psalmodius’ Office was celebrated under a Double Rite, and the saint’s name appears in the Kalendar of Limoges, in the Menology of David Camerarius, in the Martyrology of Andrew Saussay, in the work of Ferrarius, in the work of Simon Martin, in the work of the Bollandists, and in the work of the Petits Bollandistes.