Although unnamed, this shell is obviously the same as that figured by Gualtieri, who also describes it very tolerably. This figure, however, is quoted by Gmelin and others for _A. virginea_; from which shell it is quite distinct: it is a thickly formed shell, the base slightly truncated, and the aperture very narrow, and reddish brown; the outer lip within is thickened. From the same collection as the last. * * * * * Pl. 85 [Illustration] IANTHINA fragilis, _Common Oceanic Snail_--_upper and lower figures_. * * * * * GENERIC CHARACTER. _Testa subglobosa, tenuis, fragilis. Spira depressa. Labium exterius medio emarginatum. Columella ultra aperturae basin producta. Animal marinum, vesicula solida pede supposita instructum._--Cuvier. Shell subglobose, thin, brittle. Spire depressed. Outer lip notched in the middle. Base of the pillar projecting beyond the aperture. Animal marine, with a solid vesicle, placed under the foot.--_Cuvier._ * * * * * SPECIFIC CHARACTER. _I. testa pallida, anfractu basali angulato; basi complanata, striata, violacea; apertura latiore quam longiore; labio exteriore profunde emarginato._ Shell pale; body whirl angulated; the base flattened, striated and deep violet; aperture broader than long; outer lip deeply emarginate. Helix Ianthina. _Gm._ 3645. _Lister._ 572. _fig._ 23. 24. _Turton._ C. D. _p._ 58. _Gualt._ _tab._ 64. 0. _Mart._ v. _t._ 166. _fig._ 1577.-8? Ianthina fragilis. _Bruguiere. Ency. Meth._ _pl._ 456. _fig._ 1. _a. b._ * * * * * The singular shells of this genus float on the surface of the ocean, where they principally live. Gmelin remarks that the animal emits a phosphoric light; and Captain Cook observed that it is oviparous, and discharged, on being touched, a liquor of the most beautiful purple. Dr. Turton and Mr. Dillwyn have recorded several British localities for this shell; and the former notes having seen it alive, but without giving any original account of the animal. The extreme brittleness of the shell is such, that, although common, it is very rarely seen so perfect as here represented, from shells in my own cabinet. All the figures I have seen are very defective. * * * * * IANTHINA globosa. _Globular Oceanic Snail--middle figures._ _I. testa ventricosa, basi producta; apertura longiore quam latiore; labio exteriore leviter emarginato._ Shell ventricose, the base lengthened; aperture longer than broad; outer lip slightly emarginate. * * * * * The notch, which in _I. fragilis_ extends the whole length of the lip, in this, is very slight, and nearly central. Mr. Dubois has enabled me to figure it from specimens in the greatest perfection; it is much less common than the last.