ORDER I. ACEPHALA TESTACEA. 241, 
striated. One curious species, M. lithophagus, suspends itself to rocks, 
like the common mussel, and then perforating it, buries itself in the excava- 
tion, and is a prisoner for life. 
The common Mussel (M. edulis) is found on every coast in extraordi- 
nary abundance, and on the Eastern Continent is much used as food. The 
clam, however, is preferred in this country; but the coast inhabitants of 
France, Spain, and Great Britain consume enormous quantities of them, 
and immense numbers are carried into the interior of the country, furnish- 
ing an equally cheap and agreeable food ; but it is not easy of digestion, and 
sometimes produces symptoms of poisoning, which have been ascribed to the 
egos of asterias, on which it feeds during the summer. In the more north- 
ern countries of Europe it is also in great request as a bait for cod, ling, 
rays, and other large fishes that are caught by the line. Countless millions 
of mussels are used for this purpose, and in many places they are enclosed 
in gardens, the ground of which is covered with large stones, to which they 
attach themselves by their byssus or beard. 
“Tt is a curious fact that the rearing of mussels should haye been intro- 
duced into France, as far back as the year 1235, by an Irishman of the 
name of Walton, This man, who had been shipwrecked in the Bay de 
VAiguillon, and gained a precarious living by catching sea-birds, observed 
that the mussels, which had attached themselves to the poles on which he 
spread his nets over the shallow waters, were far superior to those that natu- 
rally grow in the mud, and immediately made use of his discovery by 
founding the first dowchot, or mussel park, consisting of stakes and rudely- 
interwoven branches. 
“Wis example soon found imitators, and, strange to say, the method of 
construction adopted by Walton six centuries ago has been maintained 
unaltered to the present day. It may give some idea of the immense 
resources that might be obtained from so many utterly neglected lagoons, 
when we hear that the fishermen of 1’Aiguillon, although they sell three 
hundred-weight of mussels for the very low sum of five franes, or four shil- 
lings, annually export or send them into the interior to the amount of a 
million or twelve hundred thousand francs.” 
Tripacna. — The animals of this genus have in the front of the shell a 
large aperture with denticulated margins ; for the protrusion of the byssus, 
which is distinctly tendinous and continuous with the muscular fibres, and 
in some of them these tendinous fibres, which suspend the animal to rocks, 
are so hard and tough, that an axe is required to separate them. 
T. Gigas. — This species is peculiar to the Indian Ocean, and is famous 
for its enormous size. The giant clam-shell, which is now to be found in 
the shop of every dealer in shells, was formerly an object of such rarity and 
