346 I Conchology. 



known afterwards to be the same as it was; and hence we hear 

 of new shells in the cabinets of collectors, which have no real 

 existence as separate species, but are those well known, disguised 

 by polishing. To caution the reader against errors of this kind, 

 it may be proper to add the most remarkable species thus usually 

 altered. 



The oynx shell or volute, called ihe purple or violet tip, which 

 in its natural state is of a simple pale brown, when it is WTOught 

 slightly, or polished w'ith just the surface taken off, is a fine 

 bright yellow; and when it is eaten away deeper, it appears of a 

 fine milk-white, with the lower part bluish; it is in this state that 

 it is called the onyx shell; and it is preserved in many cabinets 

 in its rough state, and in its yellow appearance, as a different spe- 

 cies of shell. 



The violet sliell, so common among the curious, is a species of 

 porcelain, or common cowry, which does not appear in that ele- 

 gance till it has been polished; and the common sea ear shows itself 

 in two or three different forms as it is more or less deeply wrought. 

 In its rough state it is dusky and coarse, of a pale brown, on the 

 outside, and pearly within; when it is eaten down a little way 

 below the surface, it shows variegations of black and green; and 

 when still farther eroded, it appears of a fine pearly hue within 

 and without. 



The nautilus, when it is polished down, appears all over of a 

 fine pearly color; but when it is eaten away only to a small depth, 

 it appears of a fine yellowish color with dusky veins. The bur- 

 gau, when entirely cleared of its coat, is of the most beautiful 

 pearl color; but when slightly eroded, it appears of a variegated 

 mixture of green and red; whence it has been called parroquet 

 shell. The common helmet shell, when wrought, is of the color 

 of the finest agate; and the muscles, in general, though very plain 

 shells in their common appearance, become very beautiful when pol- 

 ished, and show large veins of the most elegant colors. The Per- 

 sian shell, in its natural state, is all over white, and covered with 

 tubercles: but when it has been ground down on a wheel, and pol- 

 ished, it appears of a gray color, with spots and veins of a very 

 bright and highly polished white. 



The limpets, in general, become very different, when pohshed, 

 most of them showing very elegant colors; among these the tor- 

 toise-shell limpet is the principal; it does not appear at all of that 

 color or transparence till it has been wrought. 



That elegant species of shell called the jonquil chama, which 

 has deceived so many judges of these things into an opinion of 

 its being a new species is only a white chama with a reticulated 



