This purled stitch is the slipped one of previous round.
Ryder, H. P., Cycling and Shooting Knickerbocker...(2011)
Knit 5, purl 1, slip 2, purl 4, slip 2, &c. ending, the row with 1 purled stitch and 5 knitted.
Watts, Miss, The Ladies' Knitting and Netting Bo...(2010)
The thread is to be placed round it, as for a purled stitch.
Unknown, The Ladies' Work-Book—Containing In...(2010)