A composite volume containing two Welsh medicinal texts. Pp. 1-236 are in the hand of Edward Williams ('Iolo Morganwg') and contain a corpus of medicinal prescriptions, a Latin-Welsh list of herbs, etc., reputedly compiled by Hywel Feddyg ab Rhys ab Llywelyn ab Philip Feddyg of Cil Gwryd in Gower [co. Glamorgan] from the books of his ancestors Rhiwallon and his three sons Cadwgan, Gruffudd, and Einion, the original 'Meddygon Myddvai' (physicians of Myddfai, co. Carmarthen) and those of their descendants (see note on p. 236). The text was allegedly transcribed by Edward Williams in 1801 from a volume in the possession of Thomas Bona of the parish of Llanfihangel Iorwerth, co. Carmarthen, physician, which, in turn, had been transcribed by Wiliam Bona, brother of Thomas, in 1743 from a volume which had belonged to John Jones of Myddfai, physician, 'y diweddaf o dadidad o'r Meddygon ym Myddfai' (the last, by male descent, of the physicians of Myddfai) (see note on p. 236). The Welsh text was published in John Williams ab Ithel (ed.): The Physicians of Myddvai; Meddygon Myddfai. . . (The Welsh MSS Society, Llandovery, 1861), pp.89- 298, with an English translation by John Pughe of Aberdovey, co. Merloneth, ibid., pp. 301-462. Two pieces of paper pasted on to p. 256 are inscribed in the hand of Edward Williams 'Llyfr Meddyginiaeth. Cynnulliad Harri Jones o Bont y Pwl. Cefais hwn am driswllt gan Joseph Jones, Mab yr Harri Jones uchod. Iolo Morganwg', and 'Llyfr Meddyginiaeth. Llyfr Meddyginiaeth Harri Siôn' respectively. These are followed on pp. 257-370 (previously paginated 1-114) by a corpus of medicinal prescriptions, etc., in a hand other than that of Edward Williams, presumably compiled by the Harri Jones referred to in the aforementioned inscriptions.