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 6 Fam.1 Plate 11 [1854]. Onchidoris bilamellata (Linnaeus, 1767). Date: 1854. Source:
https://www.biodiversitylibrary.org/item/131598#page/132/mode/1up. Author: Albany Hancock.