ON A LARGE EXAMPLE of MEGALATRACTUS ARUANUS, L. By Charles Hedley, Conchologist. (Plates xxi.-xxii., and fig. 24). Since the appearance of Mr. H. L. Kesteven's article' on the structure of Megalatractiis ar^ianus, 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. The Trustees have lately received from Mr. P. G. Black a magnificent specimen which that gentleman procured in Torres Strait, and which is figured on the accompanying plate (PL xxi.). The subject of this note weighs ten pounds twelve ounces, the breadth is ten and a half inches, and the length one foot ten and three-quarter inches. As usual in the adult state, the apex is decollated ; by compainson with younger examples it is esti-mated that in the individual figured the styliform embryo and two and a half succeeding whorls have been removed, curtailing the total length by three-quarters of an inch. Seven whorls now remain. In the young shells the keel bears projecting nodules, but in the adult it is smooth. The original figure of this species by Rumphius,* upon which Linne founded the species,^ and from which he derived the name and locality, is reversed. That this was done by error of the engraver and not intentionally is shown by the fact that the remaining figures of Sejita tritonis, Linn., &c., upon the same plate are also reversed. This unfortunate mistake evidently caused Linne to confound this shell with the American Fulgur carica, Gmelin, which is really a sinistral shell. 1 Kesfceven — Austr. Mus. Mem., iv., 1904, pp. 419-449. 2 Desbayep — Anim. s. Vert., 2nd. ed., ix., 1843. p. 450. . •' Tryon— Man. Conch., iii., 1881. p. 52. ^ Rumphius — D'AmboinscheRariteikamer, 1741, p. 93, pi. xxviii.. fi?. A. •'■' Linnaeus— Syst. Nat., 10th. ed., 1758, p. 753.