This composite manuscript consists of five parts (f. 1; f. 2; ff. 3-13; ff. 14-45; ff. 46-108) that were produced separately between the 8th and 15th centuries and joined together in the library of Sir Robert Bruce Cotton (b. 1571, d. 1631). The manuscript contains a wide variety of theological, computistical, devotional and hagiographical materials. The fourth part (ff. 14-45), produced in the late 8th century or early 9th century (perhaps in Northern Italy), contains the only surviving copy of the Ratio de Cursus qui Fuerunt Eius Auctores (Explanation of the Liturgies, About Who Were Its Authors): a mid-8th century treatise that defends the Irish and Gallic liturgies against the claim of the advisers of Pepin the Short (b. 752, d. 768) that their liturgy was the only authentic Roman liturgy (see Mews, 'Apostolic Authority' (2017), pp. 123-24). This part of the manuscript also contains theological texts that can also be found in Arundel MS 213 and Zürich, Zentralbibliothek, MS C 64. Its contents and style of decoration suggest that it was copied from an Irish exemplar (see Dorfbauer, 'Der Codex Zürich, Zentralbibliothek C' (2017), p. 126). Contents: ff. 1r-1v: Pseudo-Jerome, Psalter of St Jerome , fragment (includes Psalms 30:17-� Text continues in the catalogue record