Description: English: Alder J. & Hancock A. (1845-1855). A monograph of the British nudibranchiate Mollusca: with figures of all the species. The Ray Society, London. Published in 8 parts:Part 4 Fam. 1 Plate 24 [1848]. Polycera lessonii d'Orbigny, 1837 synonym Palio dubia (M. Sars, 1829). Date: 1848. Source: https://www.biodiversitylibrary.org/item/131598#page/214/mode/1up. Author: Albany Hancock.