Possibly Briquet 13900 (found in a documents dated 1533 in Naples, Italy, 1536 in Imola, Italy and 1539 in Fabriano, Italy). It has been suggested this watermark is from a paper mill in the Veneto region of Italy. See Woodward, D. ‘Martha and Mary, 1568-70: The Use of a Pair of Watermarks in Reconstructing the Venetian Map Trade’, In Looking at Paper evidence and interpretation Symposium Proceedings Toronto, 1999’ p. 135. This watermark is very similar to ‘Mermaid E’ found in a document written by Michelangelo dated 1546 and identified in Roberts J. A Dictionary of Michelangelo’s Watermarks, 1988, p. 25.