Clarence W. McIlvaine was a publisher and agent for Harper & and Brothers, publishers.
In 1891, McIlvaine formed a new partnership with James Osgood, Osgood, McIlvaine & Co. In 1892, he was involved in the proposed publication of a collection of Mallarmé's quatrains, based on postal addresses. (#04348). Unfortunately, the firm did not thrive after the death of Osgood the same year, and McIlvaine closed it down a few years later in 1897.
http://paperbarn.www1.50megs.com (accessed June 2004); Tebbel, John W. A History of Book Publishing in the United States, 4 vols., New York, 1972-81.