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. 



