CHAP. VII. TDRBINiE. TROCHID^. 211 



can be said. The only two genera we can venture to 

 place in it are lanthina of Lamarck and Trichopodus of 

 Sowerby. The first consists of those pretty but fragile 

 violet and white snails which so much resemble the He- 

 licidfB : the animal has been described by Cuvier, and is 

 so very peculiar, that it cannot be arranged in any of 

 the foregoing divisions, and yet it occupies that place in 

 the Regne Animal precisely where we should have placed 

 it, — that is, immediately after Melamjms. " Theanimal," 

 observes Cuvier*, "has no operculum; but the under sur- 

 face of its foot is furnished wdth a vesicular organ, resem- 

 bling a bubble of foam, but composed of a solid substance, 

 which prevents the animal from crawling, yet allows it 

 to float on the surface of the water. The head, a cylin- 

 drical proboscis, terminated by a vertically cleft mouth, 

 and armed with little hooks, has a bifurcated tentaculum 

 on each side." Nothing, unluckily, is here said of the 

 position of the eyes; but it is sufficiently clear from this 

 short account, and also from the shell, that the lanthincB 

 belong to the family before us. We follow Lesson in 

 placing the singular genus Trichopodus as intermediate 

 between this and the last division, yet coming much 

 nearer to lanthina than to Turbo. This brings us to the 

 end of the series; and if, as we believe, Thallicera stands 

 between lanthina and Ampullaria, we reach again the 

 point from whence we commenced our survey, and 

 thus complete the entire circle of the Turbidce. 



(196.) The TROCHID.E, as a family, are distin- 

 guished from all the phytophagous Testacea, both by 

 their animals and their shells ; although much more 

 by the former than by the latter. The invaluable re- 

 searches prosecuted by the French voyagers, more es- 

 pecially by MM. Quoy and Gaimard, joined to the 

 scattered notices in other authors, have so far afforded 

 information on the animals of the Trochid^, as to 

 detach them from the Turbido', with which concho- 

 logists have hitherto mixed them. The following 



* Griff. Cuv. xii.63. 



p 2 



