Merwin-Clayton Sales Co.
Martin Gengerke notes: "A general auction firm formed by Major Emory Turner, Andrew Merwin, and George H. Clayton. Merwin and Clayton had both been with Bangs & Co. The firm was succeeded by the Merwin Sales Company [a single sale of Merwin Sales Company, from 1913, is listed here]. Few of their 603 sales had numismatic material."
Data source: content provided by auction company.