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 fragilis,
Common Oceanic Snail—upper and lower figures.
Generic Character.
- Testa subglobosa, tenuis, fragilis. Spira depressa. Labium exterius medio emarginatum. Columella ultra aperturæ basin producta. Animal marinum, vesiculâ solidâ pede suppositâ 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. testâ pallidâ, anfractu basali angulato; basi complanatâ, striatâ, violaceâ; aperturâ latiore quam longiore; labio exteriore profundè 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.
IANTHINA globosa.
Globular Oceanic Snail—middle figures.
- I. testâ ventricosâ, basi productâ; aperturâ 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.