Julius appeared as the performer on the cover of the sheet music below, copyrighted in 1906.
The same cover appears on page 16 of The Groucho Phile. After describing getting stranded in Colorado by the promoter Leroy during his first vaudeville tour, Groucho goes on:
Back in New York, I got a job with the Gus Edwards show, Boys and Girls. My picture was on the sheet music for "Farewell Killarney." Edwards, a clever man, thought my present sixteen years weren't callow enough, so he put a picture of me when I was ten or eleven on the sheet music.