A manuscript in the same hand as Cwrtmawr MS 15 containing a text entitled 'Llyfr prydferth o waith Vincentius ffranc monach ac offeiriad o ynys Lerin ynghweryl henafiaeth a gwirionedd y ffydd gatholic yn erbyn newyddiaeth pob heresi ... wedi ei gyfieithu o'r lladin ir iaith Gamberaec, heb newidio dim o synwyr a deall ei araith neu ei ymadrodd ... er mwyn denu ac annog y Cymru truain i ymgais, a chyrchu at yr hen ffydd gatholic eu henafiaid'. Following the title is a biographical note on the author, St Vincentius of Lerins, said to be 'O gatalog Gennadius', i.e. Illustrium virorum-catalogus of Gennadius Massiliensis. The translation, attributed to Hugh Owen (1575?-1642), Gwenynog, Llanfflewyn, Anglesey, is based on Vincentii Lirinensis ... pro Catholicae Fidei antiquitate et universitate, adversus profanas omnium Haereseon novationes. The translation is dated 1591, but J. H. Davies, in a note on the fly-leaf, suggests that this probably refers to an edition of the original work.