An illustration printed on a paperback cover. This decorative practice began in the early 1850s, with the publication of letters left at the pastry- cook’s by j.S. Mayhew, and was the precursor of the next trend in publishingÑyellowbacks. The sensational pictorial paper cover novels of the later 19th and 20th centuries are famous for their lurid, colourful covers. Also known as illustrated wraps.