86 ianthinidjE. 



dentition is also very similar to that of BullidcB ; and the 

 presence of eye-pedicels at the outer bases of the tentacles, 

 reminds one of the Trochidm. The greatest affinity, how- 

 ever, is, perhaps, with the Atlantidce and Carinarice, which 

 also disport themselves on the wide bosom of the ocean. 

 These "Violet-snails," as they are sometimes called, are 

 blind, but as they appear to select the night for their pre- 

 datory operations on the high seas, this deprivation can be 

 of little moment to them. 



Genus IANTHINA, Bolten. 



Shell sub-globose, violet, spiral, thin, translucent ; spire 

 short, whorls slightly angulated, nucleus sinistral, minute; 

 aperture large, quadrangular ; inner lip reflexed ; columella 

 tortuous ; outer lip thin, notched or sinuated in the middle. 



Syn. lodes, Leach. Ametistina, Schinz. Achates, 

 Gist. 



Ex. I. violacea, Bolten, pi. 09, fig. 1. Shell, I. vio- 

 lacea, fig. I, a. 



The swimming-raft, or float of cartilaginous air-sacs, which 

 serves to keep these animals at the surface, is regarded as 

 an extreme modification of an operculum by many Na- 

 turalists. The ovarian capsules are fixed to the under 

 surface of the float in order to prevent their siuking be- 

 neath the influence of the solar rays. When molested, these 

 animals exude a violet-coloured fluid, which is said to be 

 derived from the Velelhe and other pelagian Acalephs, 

 which constitute their favourite food. 



