78 NATURAL HISTORY. 



Alone- with it are some very pretty little Navicellce of different 

 shades of blue, with white spots. 



Among the Turbinidce (top-shells), two species yield " appayas," 

 that is, solid opercula fit for cheap jewellery (studs and so forth)* 

 The first is an Imperator, much resembling I t imperialis, a little grey 

 pyramidal shell warted upon every whorl, and nacreous (mother-o'- 

 pearly) throughout, except the grey outer skin (epidermis). 



The operculum, or valve, which closes the mouth of the shell, is 

 also "mother-o' -pearly/' aud looks, in fact, like a little pearl, purple 

 or violet-edged, and in shape like one-half of a tiny split bean. The 

 largest of these. opercula does not exceed £ of an inch in length. 



The second species is, I think, a Monodonta, closely allied to M. 

 labio. It is a good-sized shell, nearly as large, in the finest speci- 

 mens, as a billiard-ball, covered outside with an olive green epider- 

 mis, handsomely mottled with a darker green and with a deep 

 crimson. The whole structure of the shell is nacreous; but the 

 operculum is porcellanous (which is rather curious, but is the case 

 with some other Turbinidce). It (the operculum) is about § of an 

 inch across in the largest specimens ; and much of the shape of half 

 a split pea. The colouring is green or Spanish brown, or both ; with 

 shades of white, pink, or pale orange. 



This species has long been used in India for buttons, bracelets, 

 and the like, though not very commonly ; but I believe that I myself 

 was the first to use the operculum of an Imperator for such purposes. 



Some species of Turbo from the Pacific and South Seas are 

 much more beautiful than ours ; and at one time were a good deal 

 worked up in Paris. 



In the same family come the handsome pyramidal Trochi, gene- 

 rally marked crimson and grey. All the Turbinidce can be stripped 

 of the epidermis by steeping them in dilute acetic acid (or common 

 vinegar), and then show as entirely of mother-o'-pearl. 



In the next family [Ealiotidce) we find the Ormer or Venus's ear, 

 the largest, perhaps, and most beautiful of British shells. One or 

 two small dead shells of a similar species have been brought to me 

 here ; but I could not find out where they had been got. 



We have here, however, a remarkable member of this family, viz, 

 an Ianthina, or Oceanic snail, or " Violet shell." The connection 

 of this creature with the Ormer 8 is perhaps a little overstrained. 

 They are rock-creepers. Ianthina, ou the contrary, is at home on 

 the surface of deep " blue water" • where it congregates in great 



