38 
NATURAL HISTORY. 
[EAST. ZOOL. 
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. The Cassidea. The 
false helmet ( Cassidaria ). The harp helmet ( Cyathara ). The tun 
( JDolium ), 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. 
Table 9. 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. 
Table 10. The Magilus, 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 Purpurce; 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 
with the surface of the growing coral, that it may be enabled to procure 
its food. The Litiopce, which, continually floating about the ocean, are 
attached to the Gulph weed. The whelks {Buccinum). The needle 
shell ( Terebra). The Bullia, which has a very large animal for the 
size of the shell. The Nassa . The JRingicula, which has been con¬ 
founded with the Auricula , but only differs from the JVassce in 
having the large plaits on the pillar. 
Table 11. The Olives, Ancillaria, and butter shells, or Eburna , 
which are polished externally : as the camp olive, ( Oliva porphyria ,) 
from Panama; the Brazilian olive ( O. Brasiliensis ). 
Tables 11—14. The genera allied to the Volutes. 
Tables 11, 12. The Melons, or Cymbium, which often grow to a 
large size, and are used for domestic purposes by the Chinese and other 
Asiatic nations: as the crowned melon, and some of the Volutes. 
The young of the melons are produced alive and of a large size; the 
top of the spine is of an irregular shape like a nipple. 
Tables 12, 13. The Volutes; as the very rare courtier or red clouded 
