54 



IANTHINA. 



GENERIC CHARACTER: The shell inflated, conoidaJ, 

 thin, transparent; aperture triangular ; columella straight, 

 passing beyond the base of the right lip. 

 •I. COMMUNIS. Helix Ianthina. Turt. Lin. J. C. 

 Flem. Brit. An., p. 326. Crouch's Intro., pi. 16, fig. 3. 

 The species has been found on several parts of our north 

 and south coast; I found it myself at St. Ives, and I pos- 

 sess two or three specimens that came on shore not far 

 from my own residence. Their occurrence however, is 

 altogether casual, and depends on a combination of wind 

 and weather. The usual season is from July to November, 

 when the wind is rough or long between west or south ; 

 tinder which circumstances several floating animals, as 

 Physalia, Velella, with the lanthinae, are driven on our 

 coast from the Atlantic, sometimes in considerable num- 

 bers. This shell, however, is so brittle, as scarcely to bear 

 the touch of land ; and in consequence, vigilance must be 

 joined with good fortune, to obtain sound specimens. 

 I. EXIGUA. Turton, Mag. Nat. Hist., vol. 7, p. 352. 



Turton says. " In the small coves about the Land's-end, 

 in Cornwall, the Ianthina Fragilis (Communis) is occa- 

 sionally wafted, by a gentle south west wind, in prodigious 

 fleets ; all alive, and born up upon the water by their clusters 

 of tough bubble like vesicles. By the retreating waves, most 

 of them are carried back into the ocean; so that it requires 

 a fortunate combination of tide, wind, and wave, to see them 

 in all their splendour. This most happens about the months 

 of July and August. The fishermen's wives call them Bull- 

 horns, which supposes a prior knowledge of their appearance. 

 Among them are sometimes found a few of I. Exigua, which 

 having been probably regarded as the young of I, Fragilis, 

 may have caused them to be overlooked." " In the contri- 

 butions towards a History of Swansea, by L. W. Dillwyn, 

 Esq.," it is observed. " 1824, July. Many thousand shells 

 of Ianthina, of which some retained the animal alive ; and 

 skeletons of the Medusa Velella and of Medusa Navicula, 

 were thrown on the shores of Oxwich-bay ; the weather was 

 remarkably hot at the time. A few of these Ianthina, which 

 had before at different times been washed up in the same 

 bay, received from Dr. Leach his M.S. name of I. Rotun- 

 data; and Mr. Jeffreys informs me, that among the multitude 

 which now covered the shore, he detected a few shells of 

 I. Mediterranea mixed with them." 



MA CROS TO 31 1 A NA. 

 The shell earshaped, aperture mnch dilated, margins dis- 

 united, no columella or operculum. 



