Johannes Janssonius printer of a pirated edition of John Selden's "Mare clausum" (1636)

This note proposes Johannes Janssonius as the hitherto unidentified printer of a 1636 edition of John Selden’s Mare clausum. Previous research postulated that this edition of Selden’s treatise had been printed in Amsterdam, but no additional information about the printer has surfaced. An assessment of books printed in Amsterdam between 1628 and 1636 reveals that the pirated copy of Mare clausum shares several ornaments that also appear in works known to have been printed by Janssonius. In addition, Janssonius demonstrated a willingness to pirate other books across his career, and his cartographic sensitivity might account for the editorializing modifications made to the treatise’s engraved maps, two pieces of circumstantial evidence that help bolster the claim.