GALLERY. ] 
NATURAL HISTORY. 
37 
are rare, and hence persons have been induced to believe that reversed 
shells are always very valuable, but this is not the case. A specimen ot 
the reversed spindle shell, of the reversed bulimus, or of physse or clau- 
gili®, with the whorls in the common direction, would be as rare and 
valuable as reversed shells of those kinds which are generally ot the 
common direction. The large Chinese spindle shell, which grows to a 
^TableV The Turnip Shells ( Turbinella ), some kinds of which 
are very large and heavy. They are generally spotted when young* 
and white when adult, and from their form have been called Turnip 
Shells or Rape Shells ; these are often used as oil vessels in the Indian 
temples, and for this purpose are carved and otherwise ornamented, 
as may be seen by some in the collection. When reversed they are 
much sought for by the Ceylonese, and highly valued ; one ot these 
reversed clamp shells is in the collection : they are said to sell for a very 
large price in Ceylon and China. The Iris wave ( Turbinella pris- 
matica), so called, because when the shell is welted the periostraca 
wives out brilliant prismatic reflections. The tulip shells ( Fasciolaria ), 
among which is a kind which is by far larger than any other univalve 
shell yet discovered. The ostrich foot ( Struthiolaria ), and the 
pelican’s foot ( Aporrhais ). 
Tables 7 — 11. The genera allied to Buccinum . 
Tables 7, 8. The helmet shells ( Cassis ), some of which grow to a 
very large size, and are used to form cameos. 
Table 8. The Cassidea. The false helmet ( Cassidaria). The 
harp helmet ( Cyathura ). The tun ( Dolium ), which are often used 
in tropical climates to bale boats with. And the harps (Harpa), so 
called because the ribs left on the surface by each succeeding addition 
to the growth of the shell have been compared to the strings of a harp. 
In some species these ribs are far apart, in others close ; the latter are 
called the double-stringed or ridged harp ; they were formerly very rare. 
Tables 9, 10. The purple shell ( Purpura ), so called because, like 
many other of the animals of this kind, they emit a purple secretion 
which has been used in dyeing. The unicorn shell ( Monoceros )* 
so called because of the tooth-like horn on the front of the edge of the 
outer lip. The planaxis, which has been confounded with the peri- 
winkles. The limpet purple ( Concholepas), which was formerly ar- 
ranged with the Patella , because of the large size of the mouth of its 
shells. It exactly resembles the left valve of the heart cockle, a bivalve- 
shell, in shape, but it has the same small horn-like projection on the front 
of the outer lip. The mulberry shells ( Ricinula ), which are usually 
covered with spines, and have been thought to resemble the fruit. The 
Magillus , which, when the shell was first discovered, was thought 
by Guetard to be a stalactite, or mineral secretion ; more lately 
Lamarck placed it with the worm shells, but the animal scarcely 
differs from the Purpuras ; when the animal is young it has a thin 
shell of nearly the usual form, but of a white colour ; at a certain 
period of its growth, the animal deposits in the cavity such a quantity of 
calcareous matter as to produce the shell, in its subsequent growth, into 
a more or less elongated straight process, leaving only a small cavity 
for the body of the animal at its end. They exist in or on corals, and 
the extension of the shell is to allow the animal to keep its body level 
