Pvn H,i I'UitlS

446 mactrid^:.
lini that at Spezzia it is sought for as an article of food
and sold with other shell-fish. According to Clark this
kind is called a u nmd-hen " by the fishermen at Ex-
month. They burrow in stiff clay, six inches or more,
each individual making and occupying its own hole, and
forming together a honeycombing commonwealth. The
breadth of the shell being two inches, the length of the
siphons must be at least twice as great, in order to keep
the hole clear and have access to the water. Bouchard-
Chantereaux has remarked that S. piperata also requires
for during the recess of
or prefers to breathe pure air ;
the tide the orifice of the lower tube is considerably di-
lated, and when it is placed in a vessel of water, this tube
is gradually stretched out so as to reach the surface, and
remains for some hours in that position. Pholas has the
same habit. The earliest account we have of the animal
of the present species is that by Reaumur, published in
the ' Memoires de PAcademie' for 1710; and it has
lately been described by Bouchard- Chantereaux, Quoy,
Philippi, Deshayes, Forbes and Hanley, and Clark. I
have had the benefit of collating these descriptions wiih
my own notes made in 1836. Its anatomy has been
elaborated by Deshayes, and illustrated by twenty-two
finely-coloured plates, in one of the Appendices to the
'
Exploration scientifique d'Algerie/ The remarkable
structure of the hinge, typical of this genus, did not
escape the observant eye of Lister. The young of S. pi-
per ata has probably been mistaken for S. tenuis ;
but it
is much flatter and broader, and wants laminar teeth.
Some distorted specimens, which I found in peat, are
contracted, and consequently more convex than usual.
It is " La Calcinelle " of Adanson, Trigonella plana
of Da Costa, Venus borealis of Pennant (but not of Linne) ,
Mya hispanica of Chemnitz, Mactra Listeri and My a