402 SUPPLEMENT 
at the depth of three or four inches. They come forth from 
this retreat, re-enter it, raise themselves briskly, advance or 
recede, by means of their long fleshy pedicle, which is move- 
able in all ways, and capable of contraction and elongation, 
in a variety of directions. If they are desirous of sinking in 
the sand or mud, they elongate it, and make it penetrate as 
much forward as they can, hook themselves by its extremity, 
which they curve, then shorten it, and force the shell to ap- 
proach its point, cutting the sand with the edge. To cause 
it to spring back, they curve it into an arch, then straighten 
it quickly, and thus raise the whole body with agility. The 
same manceuvre enables them to raise themselves above the 
soil with a sort of jump. It is easy, therefore, to conceive 
how they can advance or recede by similar operations. 
The cardia are found in all known seas. The species are 
numerous, and the individuals exceedingly multiplied and 
spread in very different latitudes. In many countries of 
Europe, such as Italy, England, Holland, and the coasts of 
France, a very great quantity of them are consumed. Their 
flesh may not be very delicate, but it is, nevertheless, whole- 
some and agreeable enough. Their abundance causes them 
to be very cheap. 
The Cardium rusticum is frequent on the maritime coasts 
of the two Sicilies, where it lives sunk in sand, covered by 
about fifteen feet of water. The fishery, which is prohibited 
in summer, is made with an iron rake, with which the sand is 
worked to discover these animals. But, though the flesh is 
pretty good, none but the common people eat it. It is 
dressed with oil, crumbs of bread, pepper, and aromatic 
herbs. This species is equally found in the European At- 
Jantic. 
The Cardium edule, which is our common cockle, is fished 
up in immense quantities during winter, on the coasts of 
England, Ireland, and Holland, where they are used as food, 
13 
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