Since the appearance of Mr. H. L. Kesteven's article on the structure of Megalatractus aruanus, further notes and information have been accumulated on the subject by the writer. The size attained by this gigantic shell does not seem to be generally appreciated. It is quoted by Deshayes as "longueur 3 pouces, 11 lignes." The latest monographer, Tryon gives the length as from 8-12 inches. It appears to be the largest recent Gasteropod. So far as I am aware, no illustration of the adult shell has appeared.