142 



POPULAR CONCHOLOGY. 



outer lip thin; inner lip curved, rather oblique at the 

 base; sometimes an umbilicus; operculum 

 generally horny, thin, and spiral, of many 

 whorls. Animal, head large, terminating in 

 a short proboscis, and bearing two subulate 

 tentacles, sometimes smooth, sometimes Clll- Trochus dbeliscus. 

 ated, and two strong, separate eye peduncles 

 at their outer bases ; between the tentacles are two more 

 or less developed head lobes (nearly obsolete in some 

 species) ; next the eye peduncles, on each side is a large 

 lappet, continuous with greatly developed side lobes, 

 bearing usually three, sometimes four or five, subulate 

 cirrhi; foot more or less lanceolate, or oblong, an oper- 

 culigerous lobe on its upper surface, bearing a many- 

 spiral horny operculum; gill very long, linear; tongue 

 rather long, each series of denticles composed of a central 

 element flanked by fine hooked lateral, and numerous 

 narrow, accessorial teeth.* — Almost 200 species ; also 

 fossil. 



There are many handsome shells belonging to this 

 genus, and they are found in various parts of the world ; 

 the British species (about sixteen) occur on various parts 

 of our coasts ; some are pretty, but they do not attain the 

 size or beauty of the foreign kinds. Their peculiar conical 

 shape, and flattened base, together with the iridescent 

 aperture, and beautiful pearly appearance, render them 

 easy to be distinguished. 



Philippi enumerates the following as sub-genera : — 

 Pyramis Schum. ; Polydonta Schum. ; Clanculus Montf. ; 

 Craspedotus Phil. ; Labio Oken ; Euchelus Ph. ; Diloma 

 Phil. ; Chlorostoma Sw. ; Oxystele Phil. ; Osilinus Phil. ; 



* Forbes's British Moll. 



