Irving Joslyn (fl. 1930s) was a frequent contributor during the first years of Genii magazine.
This was possibly one of William Larsen's pseudonyms when publishing his own tricks in Genii. Although Larsen did have a lawyer friend named John W. Joslyn (born January 9, 1896). In MUM (May 1988) an article states that "... one of his best friends, the late William W. Larsen, Sr., who was a top criminal lawyer. Their courtroom battles were famous, often followed by lunch and magic tricks; for it was Larsen who introduced Joslyn to the art of prestidigitation..."