According to Cook and Wedderburn (XXI.305), the Supplementary Cabinet was 'a cabinet which Ruskin placed in the School but did not fill'; the examples which they listed were placed there shortly before their catalogue was published in 1906.
Presented by John Ruskin to the Ruskin Drawing School (University of Oxford), 1875; transferred from the Ruskin Drawing School to the Ashmolean Museum, c.1949.
Ruskin, John, ‘The Ruskin Art Collection at Oxford: Catalogues, Notes and Instructions’, Edward T. Cook and Alexander Wedderburn, eds, The Works of John Ruskin: Library Edition, 39 (London: George Allen, 1903-1912), 21, cat. Supplementary no. 178